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FLORIDA
-MUSEUM
OF NATURAL HISTORYTM
BULLETIN
MAGNETOSTRATIGRAPHY AND PALEONTOLOGY OF WAGNER
QUARRY, (LATE OLIGOCENE, EARLY ARIKAREEAN)
BASAL ARIKAREE GROUP OF THE PINE RIDGE REGION,
DAWES COUNTY, NEBRASKA
F. Glynn Hayes
Vol. 47, No. 1, pp. 1-48
2007
UNIVERSITY OF FLORIDA
GAINESVILLE
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MAGNETOSTRATIGRAPHY AND PALEONTOLOGY OF WAGNER QUARRY,
(LATE OLIGOCENE, EARLY ARIKAREEAN) BASAL ARIKAREE GROUP OF
THE PINE RIDGE REGION, DAWES COUNTY, NEBRASKA
F. Glynn Hayes'
ABSTRACT
Mammalian fossils (the Wagner Quarry local fauna) from the basal Arikaree Group (Late Oligocene) near Chadron, Dawes County, Nebraska,
are described. It is the first large mammal concentration described from the Pine Ridge Arikaree Group. Twenty-seven species of mammals are
present: 1 marsupial (Herpetotherium), 2 insectivores (Proscalops, Ocajila), 9 rodents (Downsimus, Alwoodia, Cedromus savannae n. sp.,
Nototamias. Agnotocastor, Palaeocastor, Proheteromvs, Leidvymvs, Geringia), 3 lagomorphs (Palaeolagus [2 sp.], Megalagus), 3 carnivores
(Paradaphoenus, Canidae, Nimravus), 3 perissodactyls (Miohippus, Diceratherium [2 sp.]), and 6 artiodactyls (Entelodontidae, Desmatochoerinae,
Leptauchenia, Anthracotheriidae, Pseudolabis, Nanotragulus). Faunal correlation with the Ridgeview local fauna and the radioisotopically
constrained faunas of the Wildcat Ridge indicates an early Arikareean (Arl, 30-28 Ma, Tedford et al. 2004) North American Land Mammal age
for the fauna. The first paleomagnetic study of the Pine Ridge basal Arikaree Group (Wagner Quarry section) shows that polarity signals are not
the same as basal Arikaree Group sediments (Gering Formation) in the Wildcat Ridge region. Correlation of the Wagner Quarry section with
Chron 1 On (28.25- 28.9 Ma) places it older than the Gering Formation (Chron 9r, 27.95-28.25 Ma) and younger than the lowermost White River
Group "Brown Siltstone" (Chron 10r-1 In, 28.9-30.08 Ma) of Nebraska. These sediments could represent time not recorded in the Wildcat
Ridge. Cedromus (Sciuridae), Oligospermophilus (Sciuridae), and Alwoodia (Aplodontidae) are newly recognized in the earliest Arikareean
(Arl) of the central Great Plains.
Key Words: Arikareean, Arikaree, Nebraska, Pine Ridge, paleomagnetics, Wagner Quarry, Alwoodia, Cedromus.
TABLE OF CONTENTS
Intro du action ............................................................................................................. 2
H history of Investigation.............................................................. .......................4...
M ethods................................................ .........................................................4...
G eology................................................ ... ............................. ............. ....
Paleom agnetic R esults.................................................................. ....................... 1 0
W agner Q uarry Local Fauna........................................................... .................. 14
Herpeththerium fui gax Cope 1873....... .... ........................................... 14
Proscalops sp........................... ...... ......................... 7
Ocajila makpiyahe M acDonald 1963................................... ...................... 17
Downsimus chadwicki MacDonald 1970............................ .................... 18
A lw oodia cf A m agna........................................................ ..................... 18
Cedrom us savannae n. sp...................... ................................................ 20
N ototam ius sp.................................................................... ..................... 23
Agnotocastor sp............. ....................................................... 23
P alaeocastor sp .................................................................. ....................... 24
Proheteromys cf. P. nebraskensis Wood 1937.............................................. 24
Leidymys black M acDonald 1963..................................... ..................... 24
Geringia mcgregori M acDonald 1970.............................. ....................... 24
Palaeolagus hypsodus Schlaikjer 1935............................. ....................... 25
Palaeolagus philoi Dawson 1958....................................... ..................... 25
M egalagus cf. M prim itivus.............................................. ....................... 25
Paradaphoenus tooheyi Hunt 2001.................................... ..................... 27
Canidae .......... .............. ......................... 27
Nimravus brachvops (Cope) 1878....... .............................. ..................... 27
M iohipp us sp ................... ......................................... ..................... 27
'University of Nebraska State Museum, University of Nebraska, Lincoln, Nebraska, 68588
Hayes, F. G. 2007. Magnetostratigraphy and Paleontology of Wagner Quarry, (Late Oligocene, Early Arikareean) Basal Arikareean Group of the Pine
Ridge Region, Dawes County, Nebraska. Florida Museum. Nat. Hist. Bull. 47(1):1-48.
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
Diceratherium Marsh 1875............................................... ...................... 29
Diceratherium annectens (Marsh) 1873........................... ...................... 29
Diceratherium armatum Marsh 1875.............................. ........................ 31
Entelodontidae indet.................. ... ........................ 32
Desmatochoerinae indet................................................... ......................... 32
Leptauchenia major Leidy 1856................................................................ 32
Bothriodontinae indet........................................................ ...................... 32
Pseudolabis dakotensis Matthew 1904........................... ......................... 37
Nanotragulus loomisi Lull 1922....................................... ....................... 37
Age and Correlation....................................................................................... 39
Summary and Conclusions............... .................................................... 43
Acknowledgements........................................................................ ..................... 44
References........................................................ ................................................ 44
INTRODUCTION
The lower and middle Arikaree Group in Nebraska con-
sists of two major west-east trending paleo-valley fill
sequences, one exposed in the northern Pine Ridge re-
gion and the second exposed in the North Platte Valley
and Wildcat Ridge area (Fig. 1). Historically, these two
deposits have been equated on the basis of lithologic
and biostratigraphic similarities, although lateral conti-
nuity of the lower sediments has never been demon-
strated. Specifically, the basal Arikaree fluvial deposits,
exposed in the Pine Ridge region, have often been re-
ferred (see Tedford et al.1987) to the basal Arikaree
Group, Gering Formation, originally described by Darton
(1899) at the Wildcat Ridge. Swinehart et al. (1985) re-
stricted the Gering Formation to pumice-bearing beds
that are not present at Pine Ridge. This has reopened
the question as to where and how the Pine Ridge basal
fluvial valley fill sequences fit into the history ofArikaree
deposition and how their faunas fit into the biochronologic
system of the North American Land Mammal ages
(NALMA).
Biostratigraphic comparison has provided some
support for the age correlation of these two deposits
representing the early Arikareean (30- 28 Ma) NALMA
(Tedford et al. 1987; Tedford et al. 1996; Tedford et al.
2004). When Wood et al. (1941) proposed the NALMA
system, they defined and characterized the early
Arikareean using fossils recovered from the Gering For-
mation in the Wildcat Ridge and correlative faunas from
the lower Sharps Formation of South Dakota. However,
due to the lack of described faunas from the Pine Ridge
lower Arikaree rocks to compare with the better known
(Tedford et al. 1996), although largely informally reported
(Martin 1973; Swisher 1982) faunas of the Gering For-
mation in the Wildcat Ridge, detailed correlation with
the Pine Ridge Arikaree has not been possible.
Martin's (1973) dissertation that described the
Gering faunas in the stratigraphic context of Vondra et
al. (1969) was later updated by Swisher (1982) who
produced a more refined biostratigraphic study. Swisher
divided the sediments above the Whitney Member of
the Brule Formation into Gering units A through D and
referred the massive eolian sandstones above the Gering
to the Monroe Creek Formation of Hatcher (1902). Later
(Swinehart et al. 1985), Swisher's Gering A was re-
moved from the Gering Formation and referred to the
"Brown Siltstone" and his Gering B-D was designated
the revised Gering Formation that was made up of pum-
ice bearing channels along the Wildcat Ridge. These
faunas are now well-constrained by 40Ar/39Ar radioiso-
topic dates (Woodbume & Swisher 1995; Tedford et al.
1996).
Interest in establishing a firmer correlation between
the Pine Ridge Arikaree and Wildcat Ridge deposits,
which would aid in refining the biochronology of the
Arikareean NALMA, has led to the discovery of sev-
eral rich fossil sites in the Pine Ridge region. A small
locality (UNSM Dw- 108) was studied by Martin (1973)
south of Chadron that yielded Herpetotherium, Ocajila,
Domnina, Palaeolagus, Megalagus, Downsimus,
Meniscomys, Agnotocastor, Proheteromys, Leidymys
black, and Geringia mcgregori. Bailey (1992, 1999,
2004) described another micro-mammal site (UNSM
Dw- 121) that he termed the Ridgeview local fauna (lf),
which yielded 35 mammal species, the most diverse single
site reported for the early Arikareean. The third locality,
and the subject of this report, was found by R. Tedford
and T. Galusha in 1975 near the town of Chadron, at the
base of the Pine Ridge Arikaree Group. They named
the site Wagner Quarry after the land owner at the time.
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
Figure 1. Location map of study area and Wagner Quarry.
Since its discovery, fossils have been collected intermit-
tently by joint teams from the American Museum of
Natural History and the University of Nebraska State
Museum.
This study of the Wagner Quarry fossils, herein
named the Wagner Quarry local fauna, is the first sys-
tematic description of a micromammal fossil fauna and
large mammal concentration from the Pine Ridge re-
gion. Peterson (1907) described large mammals from
the Pine Ridge Squaw Butte region, north of Harrison,
Nebraska, but these were isolated finds. More signifi-
cantly, this is also the first paleomagnetic study of basal
Arikaree Group rocks at Pine Ridge. Bailey's (2004)
biostratigraphic study reported only faunal lists from the
localities. MacFadden & Hunt (1998) paleomagnetically
sampled the upper Arikaree Group (Harrison Forma-
tion; Anderson Ranch= "Upper Harrison" Formation,
[Hunt 2002]) and the middle (Monroe Creek of Hatcher
1902) to lower Arikaree interval but did not sample most
of the lowest fluvial facies of the basal Arikaree at Pine
Ridge. Prothero sampled paleomagnetically the White
River Group of the Pine Ridge region, but did not study
the Arikaree Group sediments (Tedford et al. 1996:
Prothero & Whittlesey 1998).
HISTORY OF INVESTIGATION
Wagner Quarry was discovered and surface collected
by R. Tedford and T. Galusha in 1975 in a brief recon-
naissance of the basal Arikaree Group around Chadron,
Nebraska. They returned several times over the next
decade and collected horse, rhino, camel, Nanotragulus,
and oreodont material. Tedford believed the fossils rep-
resented a lower Gering/Sharps equivalent fauna
(Tedford, pers. comm., 2003).
In 1981 a joint team from the American Mu-
seum and the University of Nebraska returned to the
site and collected a varied fauna, including a juvenile
Pseudolabis skull (F:AM 141372) and an anthracothere
mandible (F:AM 141369). A second channel fill higher
in the section (see Fig. 5), discovered by M. Skinner in
1981 as well, also yielded material of leptauchenine
oreodonts and several species of rodents (e.g.,
Palaeocastor, Geringia). Collection has continued un-
til present as erosion exposes more fossils both in the
quarry and in the upper channel. The skull of Cedromus
savannae n. sp. (UNSM 48448) was discovered in 2001
by S. David Webb.
The fauna from Wagner Quarry was first men-
tioned in the field trip guidebook for the 45th annual SVP
meeting by Tedford et al. (1985). They briefly described
the quarry along with other mammal fossils collected
from the basal Arikaree deposits near Chadron. Wagner
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
Quarry was labeled on the cross section (Tedford et
al.1985: 340, Fig. 2, cross section C-C'). The local fau-
nas collected from Wagner and other localities around
Chadron were listed as containing: Heliscomys woodi,
Kirkomys schlaikjeri, Sanctimus stuartae, Leidymys
black, Geringia mcgregori, Palaeolagus philoi,
Arretotherium, "Pseudocyclopidius" (Leptauchenia)
major, Pseudolabis, Nanotragulus, Hypertragulus,
Miohippus, and Diceratherium. On the basis of these
taxa Wagner Quarry was correlated to the early
Arikareean. Hunt (2001) later described a new species
of Paradaphoenus, P tooheyi, in part based on a man-
dible recovered from Wagner Quarry. This species is
intermediate in morphology between an Orellan species
and a later medial Arikareean species.
The fauna from the quarry and the geology have
never been completely described until this report. Bailey
(2004) presented a faunal list (Table 1: 87) from a nearby
basal Arikaree locality, the Ridgeview If(UNSM local-
ity Dw-121), that contains the same taxa of microfauna
as in the Wagner Quarry lf. Bailey's biostratigraphic
correlation of the Ridgeview If places it slightly older
than the Gering B-D faunas of the Wildcat Ridge, but
younger than the Wildcat Ridge "Brown Siltstone" (=
lower Sharps Formation) that has produced the earliest
Arikareean taxa (Tedford et al. 1996; Tedford et al.
2004).
As part of a study on the correlation of the Arikaree
Group of the Pine Ridge (Hayes 2004), the Wagner
Quarry local fauna is described along with the magnetic
stratigraphy of the Wagner Quarry section.
METHODS
Some of the small mammals were identified through
comparison with the Ridgeview If (Bailey 2004), which
contains abundant and more complete material of many
of the smaller mammal taxa found in Wagner Quarry.
Otherwise, mammals were compared with reference
material in the University of Nebraska State Museum
collections, the Frick Collection at the American Mu-
seum of Natural History, and with taxa discussed in ap-
propriate literature. Anatomical terminology follows that
of current literature reviews of the major taxonomic
groups mentioned in systematic discussions. All mea-
surements are in millimeters unless otherwise stated.
Tooth measurements were taken at the base of the crown
along the principal cusp axes. Words placed in quotes
are informal terms, uncertain, or represent outdated ter-
minology retained for purposes of discussions. Referred
specimens are from Wagner Quarry unless otherwise
noted. Illustrations and photos of taxa omit "I" as a speci-
men designation because of its resemblance to the num-
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
N".Z- -- .D -
Figure 2. Photographs of outcrops and measured Wagner Quarry section. See Figure 5 for stratigraphic position. A,
Wagner Quarry, view to the North, top of channel marked by dashed line; B, stacked overbank deposits above
Wagner Quarry, view to north, local unconformities marked by dashed lines; C, top of Wagner Quarry section
showing overbank deposits and "top channel" sands, view to north, base of channel marked by dashed line, Dave
Webb for scale; D, expanded view of "top channel" butte, view to northwest; E, close view of Wagner Quarry basal
Arikaree sandstone, Cedromus skull in coarser channel sand; F, close view of Wagner Quarry channel cross bedded
sand with lithic clasts.
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
Figure 3. Photographs of outcrops and measured Wagner Quarry section. See Figure 5 for stratigraphic position. A,
close view of clay and siltstone pebble clasts in Wagner Quarry channel; B, close view of hematite stained and
cemented cross-beds in Wagner Quarry channel; C, close view of 1st ripple layer, above Wagner Quarry, showing
local diastem marked by clay stringer; D, "upper fossil channel" and 2nd ripple layer, dashed line marks channel base;
E, Wagner Quarry section showing 'st ripple layer below "upper fossil channel", sediments in between are interpreted
as overbank deposits; F, close view of "upper fossil channel" showing fine scale laminae and small fossil burrows; G,
close view of large fossil burrow infilled with siltstone gravels and sand in "upper fossil channel".
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
ber "1".
Abbreviations.- (others defined in text, tables, or
figures); ap, anterior to posterior measurement, length;
apt, anterior to posterior measurement of trigonid on
lower molars, length; F, Fauna; Fm, Formation; L, left;
If, local fauna; M, mean; m# or M#, molar, lower case
for lower molar; N, number of specimens; OR, observed
range of variation; p# or P#, premolar, lower case for
lower premolar; R, right; tr, transverse measurement,
width; tra, transverse measurement of anterior trigonid
width in lower molars; trp, transverse measurement of
posterior talonid width in lower molars.
Institutional abbreviations.- AMNH, American
Museum of Natural History, New York; F:AM, Frick
Mammal Collection of the American Museum of Natu-
ral History, New York; LACM, Los Angeles County
Museum, Los Angeles, California; SDSM, South Da-
kota School of Mines, Rapid City, South Dakota; UC,
University of Chicago collections, Field Museum, Chi-
cago, Illinois; UCMP, University of California Museum
of Paleontology, Berkeley, California; UF, University of
Florida collections, Florida Museum of Natural History,
Gainesville, Florida; UNSM, University of Nebraska State
Museum, Lincoln, Nebraska; YPM, Yale Peabody
Museum, Yale University, New Haven, Connecticut.
GEOLOGY
The Wagner Quarry section consists of a stack of flu-
viatile sediments, alternating between channel fill, bar
deposits, and floodplain or over-bank deposits separated
by local diastems that show slight pedogenic alteration
at the top of many of the beds.
The base of the measured Wagner Quarry section
(Fig. 2A) does not have a contact between the fluvial
Arikaree and the underlying "Brown Siltstone" (= lower
Sharps) member of the Brule Formation. However, both
north and south of the Wagner Quarry on Dead Horse
Road, there are outcrops of Arikaree gray, cross-bed-
ded fine-medium sands unconformably overlying light
pinkish to tan siltstones of the White River Group. The
southern contact outcrop exposes the Nonpareil Ash
(NP) (Swinehart et al. 1985), approximately 6m topo-
graphically below Wagner Quarry, as shown in Figure 5
(Stratigraphic distance could not be determined due to
ground cover). This ash in the Pine Ridge has been cor-
related to the NP3 ash (Tedford et al. 1996) that is ex-
posed at Wildcat Ridge. This ash at Wildcat Ridge was
dated using 40Ar/Ar39 to 30.05 +/- 0.19 Ma (Tedford et
al. 1996; Swisher & Prothero 1990).
The base of the Wagner Quarry section is a chan-
nel deposit of fine gray, trough cross-bedded epiclastic
sand and pebble conglomerates (Fig. 2F) with occasional
2:
~LL
Figure 4. Photographs of outcrops and measured Wagner
Quarry section. See Figure 5 for stratigraphic position.
A, "top channel" sandstone butte showing eroded base
of channel and large scale bedding; B, close view of
"top channel" base showing local incision; C, close view
of top of overbank deposits showing mottling and clay
clumping interpreted to be pedogenic alteration.
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
Wagner Quarry
Section
Lithostratigraphy
-- - -
---- .
. . m
::: :: : : :: :: : : : : ::
Elevation (ft)
3955-
3945-
3935-
3925-
3915-
3905
3895-
3885-
3875-
3865-
3855-
3845-
3835-
3825-
Legend
. . .* S i~*s
- Fig. 4, A
Fig. 4, B
- Fig. 2, C,D
Fig. 3, D
i- Fig. 3, G
Fig. 3, F
weakly cross-stratified
very fine to fine loosely
consolidated sandstone
with dispersed pebble clay
clasts
fine loosely consolidated
sandstone with pebble size
clay clasts at base
massive very fine to
fine loosely consolidated
sandstone
massive sandy siltstone
massive silty to sandy
mudstone
v~r~.xr~rn
*1.**
Fig. 3, E
CEf
- Fig. 2, B
finely cross-stratified very
fine to fine loosely
consolidated sandstone
with burrows and rhizoliths
very thin bed mudstone
ripple-laminated siltstone
with flaser bedding and
massive silty mudstone
coarsening towards top
with pedogenic features
at top
trough cross-stratified pebble
conglomerate lenses in
very fine to medium loosely
consolidated sandstone
iron oxide stained
: lij;-" trough cross-stratified
l..:'_ . very fine to fine loosely
consolidated sandstone
. Nonpareil Ash Zone- 3
---- --- -
----- - - - - _
***aga ***----***----
----..-...-- -----
"". S'"B.?."..y."S"
Cl
.............................
to: ME =_ l_
...............
..............
...............
A
. . . L. IL IL L. IL Ill a. &
------------
.......................
Figure 5. Lithostratigraphy of Wagner Quarry measured section and nearby outcrop of "Brown Siltstone".
Fig. 4, C
Fig. 3, A, B
-- Fig. 2, E
-Fig. 2, F
- Fig. 2, A
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
Wagner Quarry
Section
Elevation (ft)
3955.
3945-
3935-
3925 -
3915 -
3905 -
3895-
3885
3875
3865-
3855-
3845-
Figure 6. Stratigraphic placement within Wagner Quarry measured section of fossil mammals constituting the Wagner
Quarry local fauna described in text.
Lithostratigraphy
.. . . . :
oM oil 6
-- ^^
y--, -lCC~ S
Diceratherium armatum
WAGNER QUARRY
Herpetotherium fugax
Ocajila makpiyahae
Proscalops sp.
Downsimus chadwicki
Alwoodia sp.
Cedromus savannae n. sp.
Nototamias n. sp.
Agnotocastor sp.
Palaeocastor nebrascensis
Leidymys black
Geringia mcgregori
Palaeolagus hypsodus
Palaeolagus philoi
Megalagus cf. M. primitivus
Paradaphoenus tooheyi
Canidae indet.
Nimravus brachyops
Miohippus sp.
Diceratherium armatum
Diceratherium annectens
Entelodontidae indet.
Eporeodon sp.
Bothriodontinae indet.
Pseudolabis dakotensis
Nanotragulus loomisi
UPPER FOSSIL CHANNEL
Palaeocastor nebrascensis
Leidymys black
Geringia mcgregori
Proheteromys nebraskensis
Leptauchenia major
Nanotragulus loomisi
C
----------------------------
.............
..............
..............
hematite staining (Fig. 3B), and grey to buff trough cross-
bedded clayey siltstone pebble clast conglomerates (Fig.
3A) interbedded with very fine to coarse weakly cross-
bedded fine to coarse sand with scattered claystone
pebbles (Fig. 2E). This channel fill fines upward where
it is truncated and partially incised by a lighter pale green-
ish-gray massive silty mudstone that represents an over-
bank deposit. A sequence of similar over-bank deposits
overlie the first (Fig. 2B), many of which are marked
along their upper boundaries by slight pedogenic alter-
ation (Fig. 4C) and rhizoliths. This suggests a relatively
brief period of non-deposition before deposition of a new
bed by flooding. Although fragmentary fossil bones have
been collected from these rocks, the only identifiable
bone is a large calcaneum of Diceratherium armatum
(Fig. 14K: F:AM 141386) collected just above the quarry.
The over-bank sequence is interrupted by a layer
of uniform flaser bedded clay to siltstone ripples repre-
senting a low mean flow velocity, probably away from
the main channel during a low water stage. The "1st
ripple layer" (Fig. 5) is draped by a tuffaceous silty
claystone stringer (Fig. 3C). This lithology is reproduced
several times in the section, occurring above the "upper
fossil channel" and below the "top channel". The "up-
per fossil channel" grades into this depositional mode
(Fig. 3D) and the ripple layer at the top of the section is
laterally traceable into massive or flat bedded sandy silts.
The "upper fossil channel" consists of finely cross-
stratified, very fine to fine, loosely consolidated sands,
with interspersed claystone pebble clasts (Fig. 3F). Trace
fossils are relatively common in this deposit as com-
pared to the Wagner Quarry channel, which has very
few. Besides small invertebrate burrows and rhizoliths,
there are large burrows filled with intraformational
pebbles (Fig. 3G). The more complete rodent,
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
Nanotragulus, and leptauchenine material was collected
from these infilled burrow deposits. Also, turtle, frag-
mentary oreodont, and other mammal bone fragments
were collected directly from the channel deposit. The
channel deposit fines upward into a second ripple layer,
which lies below another massive over-bank deposit that
grades upward (unlike the lower over-bank deposit) into
distal fluvial silty sands and very fine sands.
The upper most part of the section is dominated
by a thick sequence of weakly trough cross-stratified,
otherwise massive, very fine to fine, loosely consolidated
sand with dispersed intraformational clay to siltstone
clasts (Figs. 2C, D; 4A). This "top channel" deposit has
an intraformational pebble conglomerate with a fine to
medium sand matrix at its base, which is slightly incised
into the underlying deposits (Fig. 4B). Neither fossils
nor invertebrate burrows or rhizoliths were found in this
unit. Overall, as one ascends the section, the channel
deposits become better sorted and more mature. This
probably indicates a reworking of local sediments by
streams with diminished flow velocity.
The channel sequences are also suggestive of a
drying climatic trend for the area. Wagner Quarry has
produced taxa that are typically found in wetter riparian
environments (Fig. 6) such as alligators, anthracotheres,
and beavers (Agnotocastor). That leptauchenine
oreodonts are found only in the smaller "upper fossil
channel" along with a partial Palaeocastor skull, (Fig.
6) suggests that the "upper fossil channel" likely sampled
a drier environment than the channel of Wagner Quarry.
PALEOMAGNETIC RESULTS
To determine the magnetostratigraphy of the Wagner
Quarry section, 11 sites were selected at 3-4.5m (10-
15') stratigraphic intervals. At each site, three separately
Table 1. Paleomagnetic results for individual sites at the Wagner Quarry measured section
Site Dec Inc K VGP Class Polarity Elevation A95
W1 355.9 70.9 438.6 76.9 I N 3850 5.9
W2 342.3 62.5 126.8 77 I N 3863 11
W3 19.3 73.5 378 69.4 I N 3870 6.3
W3A 96.4 52.7 21.9 17.6 I N 3880 27
W4 27.9 70.9 20.6 67.9 I N 3890 27.9
W5 351.1 61.2 203.2 83.4 I N 3905 8.7
W6 179.8 -44.4 3.4 -73.6 I R 3915 81
W7 128.6 -18.6 25.3 -34.5 I R 3925 25.1
W8 353.4 64.9 74.2 83.6 I N 3935 14.4
W9 Not used 3945
W10 314.3 23.6 17.6 40.3 I N 3955 30.3
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
A. NRM site means (N=30)
A. Demagnetized site means (N=30)
Figure 7. Equal-angle stereographic projections of all used site mean data for the natural remanent magnetization
(NRM) and site sample data after thermal demagnetization. The circles are the 95% confidence cone for the mean.
Black circles represent positive inclination, open squares are negative inclination.
oriented samples were collected. Sample orientation
was measured using a Brunton geologic compass.
Samples were recovered from the outcrop by the use of
hand tools and then drilled into 2cm cores using a non-
magnetic bit in the laboratory. The direction of magneti-
zation was measured in a 3-axis 2G Enterprises cryo-
genic magnetometer at the University of Michigan.
Thirty samples were measured (Fig. 7) for Natu-
ral Remanent Magnetization (NRM) Mean Dec: 7.6,
Inc: 70.2, N: 30, R: 27.13, k: 10.1, a95: 8.7- and then
thermally demagnetized in 8 to 10 steps. Previous stud-
ies (Prothero & Whittlesey 1998, Tedford et al. 1996,
MacFadden & Hunt 1998) identified magnetite as the
Detrital Remanent Magnetization (DRM) carrier, and
have shown that thermal demagnetization provides the
clearest paleomagnetic data in samples ofArikaree sedi-
ments. Alternating field demagnetization is not success-
ful in removing iron hydroxide overprints (Butler 1992).
Polarity directions were determined by principal
component analysis (Kirschvink 1980) and visual inspec-
tion of orthogonal demagnetization diagrams analyzed
by the Super-IAPD99 software (by Torsvik, T. H.,
Brinden, J. C., & M. A. Smethurst- available at the
following website- www.ngu.no/geophysics). Virtual
Geomagnetic Poles (VGP) were calculated using the
same program (Table 1). Figure 8 shows representative
sample demagnetization plots (Zijderveld diagrams) and
intensity decay graphs. Fisher statistics (Fisher 1953)
were used to calculate site mean directions and confi-
dence limits. Samples usually show a two-component
magnetization. The first, a secondary NRM component,
is removed between 180-220C and probably represents
a present-day magnetic overprint carried by goethite.
Directions interpreted to represent the depositional re-
manent magnetization, carried by magnetite, are revealed
between 200-550'C. Remanence levels drop below 10%
of total intensity (Fig. 8) after 580-600C, above the Cu-
rie point of magnetite.
A reversals test is not supported, due to the small
number of specimens and the incomplete removal of
normally oriented components (Fig. 7). However, all the
sites used in the Wagner Quarry section showed three
samples with concordant directions. A Class I site shows
concordant directions for all three single site samples
(sensu Opdyke et al.1977). A Class II site, of which
there were none in this study, has two concordant
samples.
Several sites exhibited very high k values (see Table
1). The only site not used, W-9, was taken from the "top
channel" sediments. It was not used because the samples
could not be hardened enough to either cut with the cor-
ing drill or hand cut into cubes.
Of the 10 criteria to rate overall quality of mag-
netic studies proposed by Opdyke (1990) and Opdyke
& Channel (1996), this study satisfies 6. They suggest
that valid modem magnetostratigraphic studies should
meet 5 or more of their criteria. As mentioned above
the antipodal test is not supported, a radioisotopic age is
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
South 4-
1 North
West, Up
cV
CD'
0"3
-a E
0.M
East, Down
East, Down
Axes of Zijderveld diagrams
W6-1 (NRM-440 C)
12060 1 Unit= 5.OmA/M
0 TEMP 100 200 300 400 500 600
Symbols: 0 Horizontal Component [] Vertical Component
Figure 8. Representative Zijderveld thermal demagnetization diagrams and decay of Natural Remanent magnetiza-
tion (NRM) intensity of the Wagner Quarry section. Numbers denote temperature steps in degrees Celsius.
W10-1 (NRM-390 C)
1 Unit =10.OmA/M
S00
TEMP 100 200 300 400 500 600
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
Wagner Quarry
VGP Lattitude
Elevation (ft)
3955-
3945
3935
3925
3915
3905 -
3895-
3885 -
3875
3865-
3855-
3845--
Lithostratigraphy
- ----- --_-
... .. .. ....
-- --i-9W` .
0.
........ .. .-...^^ y~i^='
*~~~~~ ~ ~ ~ ***' ***' ^
Symbols: Paleomagnetic site 0
0 Paleomagnetic site, unused 0
Class 1 Normal Site
Class 1 Reversal Site
Figure 9 Lithostratigraphy and corresponding Virtual Geomagnetic Poles for the Wagner Quarry section. (see Fig.
5 for lithology legend).
Magnetic
Polarity
Zonation
Paleomag.
Site No.
*W-10
QW-9
*W-8
* W-7
*W-6
*W-5
* W-4
* W-3a
*W-3
*W-2
SW-1
Table 2. Wagner Quarry local fauna mammalian faunal
list.
Mammalia
Marsupialia
Insectivora
Rodentia
Herpetotherium fugax
Ocajila makpiyahe
Proscalops sp.
Aplodontidae
Downsimus chadwicki
Alwoodia cf. A. magna
Sciuridae
Cedromus savannae n. sp.
Nototamias sp.
Castoridae
Agnotocastor sp.
Palaeocastor sp.
Heteromyidae
Proheteromys cf. RP
nebraskensis
Cricetidae
Leidymys black
Geringia mcgregori
Lagomorpha
Leporidae
Palaeolagus hypsodus
Palaeolagus philoi
Megalagus cf. M. primitivus
Carnivora
Amphicyonidae
Paradaphoenus tooheyi*
Canidae
Canidae indet.
Nimravidae
Nimravus brachyops
Perissodactyla
Equidae
Miohippus sp.
Rhinocerotidae
Diceratherium annectens
Diceratherium armatum
Artiodactyla
Entelodontidae
Entelodontidae indet.
Merycoidodontidae
Desmatochoerinae indet.
Leptauchenia major
Anthracotheriidae
Bothriodontinae indet.
Camelidae
Pseudolabis dakotensis
Hypertragulidae
Nanotragulus loomisi
* described by Hunt, 2001
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
not available in the section (although the NPZ is present
close to the section, as mentioned in the geology sec-
tion), a field stability test is not possible, and directions
were only partially determined by principal component
analysis. The criteria fulfilled by this study include: 1)
stratigraphic age known to the level of Cenozoic stage,
2) sampling localities placed in a measured stratigraphic
section, 3) complete thermal or AF demagnetization per-
formed and vector analysis carried out using orthogonal
plots, 4) data published completely, 5) magnetic mineral-
ogy determined, and 6) associated paleontology presented
adequately.
The results show that even though the Wagner
section is relatively short, there are three magnetozones
present (Fig. 9). From the base of the Wagner Quarry
section up to the beds below the "upper fossil channel",
6 sites are of normal polarity. A short reversal, among
the otherwise normally polarized samples, is character-
ized by two Class I sites, although mean confidence lev-
els were relatively dispersed for the sites (Fig. 7; Table
1). This probably indicates incomplete removal of a nor-
mal overprint, though the individual samples all showed
clear reverse polarity. Above the reversal, there is a
normal interval also characterized by two Class I sites.
WAGNER QUARRY LOCAL FAUNA
In addition to the mammal fauna, the non-mammalian
material includes sparse fish and snake vertebrae, an
alligator premaxilla (UNSM 123224), turtle elements
(UNSM 123234 nuchal plate, UNSM 123236, humerus),
and sparse avian material (e.g.: UNSM 123449-123453).
The mammalian fauna is diverse considering that many
taxa are represented by only a single specimen. The
fauna is also relatively unique in that it contains both
micro- and mega fauna. Most sites in the Pine Ridge or
Wildcat Ridge are restricted, through taphonomic filters,
to either small mammals or isolated occurrences of larger
mammals. Twenty-seven mammalian species are
present, including a marsupial, 2 insectivores, 9 rodents,
3 lagomorphs, 3 carnivores, 3 perissodactyls, and 6 ar-
tiodactyls (Table 2).
SYSTEMATIC PALEONTOLOGY
Class MAMMALIA Linnaeus 1758
Order DIDELPHIMORPHIA (Gill 1872)
Family DIDELPHIDAE Gray 1821
Genus HERPETOTHERIUM Cope 1873
HERPETOTHERIUM FUGAX Cope 1873
Table 3
Type.-AMNH 5254, R MI-M4 (Cope 1884).
Type Locality.-Cedar Creek Beds, White River
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
Figure 10. Wagner Quarry local fauna: insectivores, rodents, and lagomorphs. A-B: UNSM 123291, Proscalops cf.
P miocaenus, L P4, A, lingual view; B, occlusal view. C-D: UNSM 123288, Ocajila makpiyahe, R p4, C, occlusal
view; D, labial view. E, UNSM 123295, Agnotocastor sp., Lp4, unworn, occlusal view. F, UNSM 123286, Geringia
mcgregori, R ml-m3, occlusal view, upper fossil channel. G, UNSM 123283, Geringia mcgregori, L ml-m3, worn,
occlusal view. H, UNSM 123286, Geringia mcgregori, L il, anterior view, upper fossil channel. J, UNSM 123287,
Leidymys black, R ml-m3, oblique occlusal view. K, F:AM 141247, Palaeolagus hypsodus, L p3, occlusal view.
L, UNSM 48452, Palaeolagus philoi, L p3, occlusal view. M, UNSM 123293, Nototamias sp., L ml-3, oblique
occlusal view. N, UNSM 123284, Palaeocastor nebrascensis, R MI or 2, occlusal view. 0, UNSM 123294,
Megalagus cf. M. primitivus, R lower cheektooth, occlusal view. Scale bars = Imm.
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
Table 3. Dental measurements for Herpetotherium fugax, rodents and Palaeolagus hypsodus (other small mam-
mal taxa in text or separate table). Specimens are from Wagner Quarry If unless otherwise stated. (Compiled from
author's measurements; MacDonald, 1970; Rensberger, 1983; Wood, 1937.)
H. fugax
UNSM 123290 UNSM 123289
M3 ap 1.90 ml/m2 ap 1.80
tr 2.15 tra 0.99
trp 1.16
FM 141248
m3 ap 1.98 m4 ap 1.15
tr 1.17 tr 1.11
Downsimus UNSM 123285
chadwicki p4 ap 2.17 ml ap 2.13 m2 ap 2.14 m3 ap 2.35
tr 1.66 tr 1.62 tr 1.77 tr 1.74
LACM 17031 (type) Sharps Fm LACM 1959 Sharps Fm
ml ap 1.83 m2 ap 1.90 m3 ap 2.41
tr 1.57 tr 1.70 tr 1.65
Alwoodia sp. UNSM UNSM UNSM UCMP
123400 81500 24088 76941
Wagner Monroe McCann Can. John Day
Quarry Creek A. harkseni A. magnus (type)
P4 ap 3.43 4.12 3.17 3.6
tr 3.84 4.18 3.26 3.75
Nototamias sp. UNSM123293
ml ap 1.42 m2 ap 1.76 m3 ap 2.01
tr 1.34 tr 1.52 tr 1.56
trp 1.39 trp 1.63 trp 1.52
Palaeocastor sp. F:AM 141246
P4 ap 3.11 MI ap 2.69 M2 ap 2.70
tr 4.87 tr 4.90-4.96 tr 4.43-4.76
F:AM 141246 F:AM 141245 UNSM 123284
M3 ap 2.65 p4 ap 4.99 MI or 2ap 3.38
tr 3.27 tr 4.28 tr 4.16
Proheteromys UNSM 123281
cf. P ap p4 1.17 m3 1.37
nebraskensis tra 0.99 1.48
trp 1.11 0.97
MCZ 5051 holotypee) Brule Fm
ap p4 1.02 ml 1.24 m2 1.20 m3 1.08
tra 1.02 1.38 1.41 1.11
trp 1.11 1.42 1.27 0.98
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska 17
Table 3. Continued
Leidymys UNSM 123287
black ml ap 1.67 m2 ap 1.55 m3 ap 1.53
tra 0.97 tra 1.26 tra 1.26
trp 1.18 trp 1.31 trp 1.08
FM 141248
Ml ap 2.02 M2 ap 1.63 M3 ap 0.95
tr 1.36 tr 1.42 tr 1.18
Geringia UNSM 123283
mcgregori ml ap 1.67 m2 ap 1.55 m3 ap 1.53
tra 0.97 tra 1.26 tra 1.26
trp 1.18 trp 1.31 trp 1.08
UNSM 123286
ml ap 1.81 m2 ap 1.75 m3 ap 1.83
tra 1.21 tra 1.63 tra 1.59
trp 1.44 trp 1.69 trp 1.42
incisor ap 1.37 tr 1.24
Palaeolagus F:AM 141247
hypsodus ap p3 2.15 p4 2.69 ml 2.69 m2 2.67 m3 1.55
tr 1.67 2.44 2.46 1.45 1.45
Formation, Logan County Colorado.
Referred Specimens.-UNSM 123289, lower
molar; UNSM 123290, R M3; F:AM 141249, L m3-4.
Discussion.-Korth (1994b) reviewed North
American Tertiary marsupials and placed all Arikareean
Herpetotherium in H. young, diagnosing the species
on the basis that upper molars possess a single central
stylar cusp. However, new material from the Ridgeview
If (=UNSM Dw-121) (Bailey 2004) and from Florida
(Hayes 2005) shows that early Arikareean
Herpetotherium possesses a variable central stylar cusp
morphology similar to H.fugax, an older species known
from Chadronian-Orellan NALMA deposits. Therefore,
Hayes (2005) extended the range of H. fugax into the
early Arikareean to encompass the Ridgeview If and
Florida specimens. The small amount of material from
Wagner is the same size and morphology (possesses
multiple stylar cusps) as the Ridgeview If
Herpetotherium and is referred to H. fugax.
Order INSECTIVORA Illiger 1811
Family PROSCALOPIDAE Reed 1961
Genus PROSCALOPS Matthew 1909
PROSCALOPS sp.
Figure 10A-B
Referred Specimen.-UNSM 123291, L P4.
Discussion.-This tooth closely matches those in
the large sample of Proscalops material from the
Ridgeview If that Bailey (2004) identified as P. cf. P
miocaenus. Measurements: ap = 2.17, tr = 1.96.
Family ERINACEIDAE Fisher von Waldheim 1817
Genus OCAJILA Macdonald 1963
OCAJILA MAKPIYAHE Macdonald 1963
Figure 10C-D
Type.-SDSM 56105, L ramus with m2-m3.
Type Locality.-SDSM V5360, Sharps Formation,
early Arikareean.
Referred Specimen.-UNSM 123288, R p4.
Discussion.-Referral of this tooth is based on
comparison with more complete dentitions from the
Ridgeview If, which were identified through comparison
to a cast of the type. There is currently only one species
assigned to the genus Ocajila, 0. makpiyahe. A single
ml (UNSM 24166) described by Korth (1992) from the
McCann Canyon If is larger than any known for 0.
makpiyahe and may be a younger second species.
Measurements: ap = 1.51, tr = 1.04
Order RODENTIA Bowdich 1821
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
Family APLODONTIDAE Trouessart 1897
Genus DOWNSIMUS Macdonald 1970
DOWNSIMUS CHADWICKI Macdonald 1970
Figure 13C; Table 3
Type.-LACM 17031, partial R mandible, with
ml-3.
Type Locality.-LACM 1959, Sharps Formation,
early Arikareean.
Referred Specimen.-UNSM 123285, L ramus
with p4-m3.
Description.-See Macdonald (1970:28-29) for
description of type ml-m3 and Storer (2002: 110-112)
for description of upper and lower deciduous premolars,
adult premolars, and molars. Measurements: p4, ap =
1.96, tra= 1.38, trp = 1.70; ml, ap = 2.04, tra = 1.52, trp
= 1.72; m2, ap = 1.86, tra = 1.58, trp = 1.68; m3, ap =
2.33, tra = 1.70, trp = 1.62.
Discussion.-UNSM 123285 is inseparable in
morphology from an observed cast of the type of
Downsimus chadwicki from the upper Sharps Forma-
tion (Macdonald 1970), which Tedford et al. (2004) cor-
relate with the Gering Formation. It falls within the mea-
surements given for a large sample of Downsimus re-
ported from the "Monroe Creek" equivalent (sensu L.J.
MacDonald 1972) Kealey Springs If (Storer 2002), ex-
cept for having a more elongate p4. This taxon is also
found in the Ridgeview If (Bailey 2004) and the Gering
faunas (Martin 1973; Swisher 1982). It has not been
reported from older faunas such as the lower Sharps
fauna or its equivalents, e.g. "Brown Siltstone" or "Gering
A" of Swisher (1982).
Subfamily ALLOMYINAE Marsh 1877
Genus ALWOODIA Rensberger 1983
ALWOODIA cf. A. MAGNA
Figures 11A; 13F; Table 3
Type.-UCMP 76941, R maxillary, P3-M3.
Type Locality.-Picture Gorge 22 (V-66116), early
Arikareean, 5m above Picture Gorge Ignimbrite (40Ar/
39Ar- 28.7 +/- 0.08 Ma, Tedford et al. 2004).
Referred Specimen.-UNSM 123400, L P4.
Description.-Anterocone is large, but smaller than
A. magna or specimens from Gering Formation, situ-
ated on anterior portion of anterior labial margin, sepa-
rated from smaller parastyle on labial margin. Mesostyle
is lengthened into loph that blocks deep central fossette.
Paracone and metacone is subequal in size with deep
labially concave face on paracone. Metacone face is
less concave. Protoconule is smaller than metaconule.
Protoconule is connected by weak lophs to paracone
Figure 11. Alwoodia upper P4s, occlusal views. A.
UNSM 123400, Alwoodia cf A. magna, L P4, Wagner
Quarry; B, UNSM 81500, Alwoodia sp., R
P4(reversed), Mo-107, Reddington Gap, "Monroe
Creek" anthills; C, UNSM 24088, Alwoodia harkseni,
McCann Canyon If; D, UCMP 76941, Alwoodia ma-
gna, holotype, R P4 (reversed), Picture Gorge 22 (V-
66116) John Day Fm.
and protocone with small lophule extending towards
anterocone. Protocone curves anterolabially to form
anterolingual fossette. Metaconule is large and sepa-
rated from metacone by shallow posterior labial fossette
and separated from protocone and small cingular hypo-
cone by posterior lingual fossette continuous with cen-
tral fossette. Measurements: ap = 3.41, tr = 3.89.
Discussion.-This tooth is referred to the
Allomyinae based on Rensberger's (1983) diagnosis:
upper cheek teeth brachyodont; ectoloph with a deep
labially concave face on the paracone, less concave on
the metacone; a mesostyle closes the labial end of the
central transverse valley; principal cusps developed into
high crests; hypocone forms part of the posterior cingu-
lum; a small double metaconule present in molars be-
hind the lingual metaconule, and in P4 it forms a small
cusp or ridge labial to the metaconule.
The Allomyinae contains three genera, Parallomys,
Allomys, and Alwoodia. UNSM 123400 differs from
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
Parallomys in lacking a comparatively wide U-shaped
central valley with a low protoloph and metaloph, in hav-
ing small accessory cusps in the anterior and posterior
valleys, in lacking flat occlusal wear, and in having the
labial faces of the paracone and metacone that slope
less lingually than Parallomys. Allomys has a more
vertical labial face on the ectoloph similar to the Wagner
Quarry tooth, but the crests of the ectoloph, protoloph,
and metaloph in Allomys are weaker and develop more
complex prominent accessory crests. Korth (1989) de-
scribed a new genus, Campestrallomys, from the
Whitneyan and Orellan of the Great Plains that has many
allomyine characters, except it lacks the double meta-
conule on the upper cheekteeth. Campestrallomys is
considerably smaller than the Wagner tooth and the P4
has a more complete ectoloph.
Two species are currently included in the genus
Alwoodia, A. magna, described by Rensberger (1983)
from the John Day region and A. harkseni, recognized
by Korth (1992) from the Great Plains McCann Canyon
If. Tedford et al. (2004) use the first appearance of A.
magna in the John Day as a characterizing taxon for
the early early Arikareean (Arl). The occurrence of
Alwoodia in the John Day, as reported by Rensberger
(1983), is chronologically well-constrained by its occur-
rence between the Picture Gorge Ignimbrite (28.7 +/-
0.07 Ma) and the Deep Creek Tuff (27.89 +/- 0.57 Ma)
(dates from Tedford et al. 2004). The chronological
range ofAlwoodia harkseni is more poorly constrained.
The McCann Canyon lf has been considered either early
late Arikareean (Ar3) (Korth 1992) or late early
Arikareean (Ar2) (Tedford et al. 2004). Alwoodia
harkseni is also morphologically different, in the devel-
opment of the ectoloph, smaller size, and more trenchant
ridge-like cusps (Fig. 11C), than the earlier Arikareean
samples discussed below. Storer (2002) referred a frag-
mentary P4 to ?Alwoodia from the Kealey Springs If of
the Saskatchewan Cypress Hills Formation, which he
correlated to the late early Arikareean (Ar2). Storer
(2002) considered planar occlusal wear a diagnostic
character of Alwoodia in comparison to other
Allomyines. The P4s illustrated in Figure 8 show four
states of wear, from the almost unworn state of A.
harkseni (Fig. 11C) to the heavily worn state of the
Wagner tooth. (Fig. 11A).
The Wagner Quarry tooth has comparatively ro-
bust cusps and a metaconule/metaloph and protoloph
with the short accessory ridges and crests on the valley
lophules that are diagnostic of Alwoodia (Rensberger
1983). It is within the size range of A. magna but has a
smaller anterocone in relation to A. magna (Fig. 11),
and the doubled metaconule is not as well- developed.
Instead, there is a simple low ridge that connects the
metaconule to the metacone. Unlike A. magna, the
mesostyle is broad and lophate with more wear. UNSM
123400 may represent a new species ofAlwoodia based
on these differences but more material is needed to make
a conclusive determination.
Additional specimens ofAlwoodia (Fig. 11B) from
the Wildcat Ridge Monroe Creek Formation are recog-
nized here for the first time. These samples contain both
upper and lower molars. A single upper molar from the
Nipple Butte Quarry, found at the base of the "Brown
Siltstone" at Wildcat Ridge (Swisher 1982), is provision-
ally referred to Alwoodia. It is highly worn but pos-
sesses the diagnostic characters of the Allomyinae
(Rensberger 1983; and see Alwoodia cf A. magna be-
low) and is a large tooth relative to other allomyine spe-
cies (Measurements: ap = 2.82, tr = 3.90), Alwoodia is
the largest genus of the allomyines. If the identification
is correct, then it represents the stratigraphically lowest
occurrence of this taxon. The "Brown Siltstone" has
been radioisotopically and magnetically dated to have
been deposited between slightly younger than 29 Ma to
slightly older than 30 Ma (Tedford et al. 1996). Two
teeth collected from Swisher's (1982) "Gering C" (=
upper Gering Formation) are here referred to Alwoodia
based on size and morphology. Two ant hill collections
(UNSM localities Mo- 107 MCAH; Mo-163) found in
the stratigraphically higher Monroe Creek Formation, or
undifferentiated Arikaree (dated by Olsen's third ash
27.79 +/- 0.08 Ma from Tedford et al. 1996), also pro-
duced a significant amount of material that can be re-
ferred to Alwoodia. Specimens in this sample are slightly
larger in size (Table 2) than A. magna and slightly more
derived, with a more developed ectoloph and additional
lophules in the fossette valleys. Formal description of
the above material is deferred to a later report.
The material of Alwoodia discussed above pro-
vides a well-calibrated early Arikareean sequence for
this rodent in both the Great Plains and the John Day
region, from the earliest definitive appearance in Wagner
Quarry to the latest Monroe Creek sample. In the P4,
there appears to be a gradual expansion of the
anterocone, increasing complexity of the inter-valley
lophules, development of the "double metaconule", and
small increase in size (Fig. 11). This lineage is probably
separate from the lineage that leads to A. harkseni,
which is smaller, and exhibits a less complex P4 with
less robust cusps.
Additional Alwoodia sp. Referred Specimens.-
UNSM locality Mo-104, Nipple Butte Quarry, (Swisher
1982, Gering A = Brown Siltstone = Sharps Formation):
UNSM 81513, RM 1 or 2. UNSM locality Mo-107 Anthill
#2 (Swisher 1982, Gering C): UNSM 81210, L dP4;
UNSM 81213, L ml. UNSM locality Mo-107, Monroe
Creek Ant Hill (Swisher 1982, Monroe Creek Forma-
tion): UNSM 81278, R M2; UNSM 81282, L dP4; UNSM
81283; R M2; UNSM 81284, L p4; UNSM 81285, R
Ml; UNSM 81286, L M2; UNSM 81287, L Ml; UNSM
81500, R P4; UNSM 81501, R Ml or 2; UNSM 81502,
R M1 or 2; UNSM 81503, L ml; UNSM 81504, R ml;
UNSM 81514, R m3; UNSM 81515, RM3; UNSM
81516, R ml; UNSM 81517, LM1 or 2; UNSM 81518,
R P4. UNSM locality Mo-163, Monroe Creek/Harrison
Formation undifferentiated: UNSM 81505, R Ml or 2;
UNSM 81506, L M3; UNSM 81507, R MI; UNSM
81508, L M1; UNSM 81509, RM1 or 2; UNSM 81510,
LMI or 2; UNSM 81512, L M1 or 2.
Family SCIURIDAE Gray 1821
Subfamily CEDROMURINAE Korth & Emry 1991
Genus CEDROMUS Wilson 1949
CEDROMUS SAVANNAE n. sp.
Figure 12A-F; Table 4
Holotype.-UNSM 48448, partial skull with RP4-
M3 and LP4-M3, M2 missing.
Etymology.-Named for Savanna S. R. Hayes.
An inspiration for this report.
Diagnosis.-Zygomasseteric structure more de-
veloped and robust than C. wilsoni and C. wardi; mas-
seteric ridge margin extending anteriorly over the in-
fraorbital foramen and dorsally higher than in C. wilsoni
or C. wardi; infraorbital foramen larger than C. wilsoni;
upper cheekteeth more quadrate than in C. wardi or C.
wilsoni; C. savannae has more lophate, less cuspate,
metaloph on upper molars; P4 more quadrate in outline
than in C. wilsoni, which is more quadrate than in C.
wardi; P4 parastyle reduced and anterior valley wider
and more U-shaped than other species; mesostyle at
base of metacone in C. savannae on P4 and at base of
paracone on molars; C. wilsoni with mesostyle at base
of paracone on all cheekteeth; C. wardi with mesostyle
equidistant from paracone and metacone on upper P4-
M3.
Description.-Skull (Fig. 12C-E): Palate is ven-
trally concave. Anterior limit of masseter is relatively
thick ridge that extends anteriorly over infraorbital fora-
men. Infraorbital foramen is oval shaped, 2.4mm dors-
oventrally. Sphenopalatine foramen occurs dorsal to M2
at maxilla, frontal, and palatine suture. Incisive foramen
is 40% of length of diastema. Rostrum is short
anteroposteriorly and deep dorsoventrally.
Upper Dentition (Fig. 12A-B): Incisor is relatively
small, with slight interwoven striations on curved ante-
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
rior face of tooth. P3 is represented by alveoli only, single
rooted. P4 is quadrate, protoloph only slightly developed,
metaloph weakly connects large metaconule to meta-
cone. Posterior cingulum begins at cusp of metacone
and extends to lingual cingulum. Small mesostyle is set
next to metacone on labial margin. Expanded parastyle
partially surrounds distinct large paracone. M1-M2 are
similar and quadrate in shape. Strong anterior cingulum
merges with expanded parastyle on buccal anterior cor-
ner. Anterior cingulum joins protocone which extends
posteriorly to distinct hypocone. A small lingual cleft sepa-
rates hypocone from protocone. Hypocone merges into
posterior cingulum which curves anteriorly and connects
with metacone. Paracone and metacone conical cusps
distinct, but not separated from protoloph and metaloph.
Metaloph is slightly expanded at indistinct metaconule
and almost incomplete, very weakly linked to protocone.
Protoloph is complete but weakly unites with protocone.
Mesostyle is present on labial margin joined at base to
paracone forming incomplete ectoloph. M3 is similar to
M1-M2, except a metacone, metaloph, and hypocone
are not present. Instead, the posterior is expanded pos-
teriorly into shallow, highly rugose basin. Small mesostyle
is present and weakly separated from base of paracone.
Discussion.-Cedromus at various times has been
referred to the Ischyromyidae (Wilson 1949), Sciuridae
(Galbreath 1953), and Aplodontidae (Black 1963; Wood
1980). Based on complete cranial material from the
Orellan of Wyoming, Korth & Emry (1991) reviewed
the genus and demonstrated that Cedromus has derived
dental and cranial features that are more similar to sciurids
than aplodontids. Cedromus as a genus is defined by its
unique zygomasseteric structure in comparison to other
sciurids (the Wagner Quarry skull shows this feature in
an even more developed state than in older species).
Korth & Emry therefore erected a new subfamily, the
Cedromurinae to recognize this distinction. He also in-
cluded the previously described Oligospermophilus
(Korth, 1987) in this subfamily.
Korth & Emry (1991) recognized three species
of Cedromus: the Orellan C. wardi, the late Orellan or
Whitneyan C. wilsoni, and a possible unnamed species
from the medial Orellan (Cedromus sp.) that has four
roots on the lower m l-m2 unlike the other species. (Note:
the ramus Korth & Emry referred to C. sp. is incor-
rectly labeled as UNSM 80133; the correct number is
UNSM 81033). Cedromus wilsoni, described by Korth
& Emry (1991) from material recovered from Converse
County, Wyoming, is the smallest species and may rep-
resent an intermontane variant of the species known
from the Great Plains; C. wardi, C. sp, and the skull
from Wagner are similar in upper dental measurements
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
A
E F
Figure 12. A-F, UNSM 48448, Cedromus savannae n. sp. partial skull with LP4-M3, RII, RP4-M1, RM3; Wagner
Quarry. A, LP4-M3, occlusal view; B, LP4-M3, oblique occlusal view; C, skull, ventral view; D, skull, lateral view;
E, skull, oblique lateral view; F, skull, anterior view. A-B, scale bars = Imm; C-F, scale bars = 5mm.
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
Table 4. Dental measurements for Cedromus savannae n. sp. and comparative measurements of other Cedromus
species. The first two molars are difficult to tell apart so measurements are duplicated for Gering sample. Table is
arranged from youngest to oldest occurence. (Compiled from author's measurements; Korth, 1991.)
C. sp. C. savannae C. sp. C. wilsoni C. sp. C. wardi
Gering n. sp. "Brown late Orellan- medial early
Fm Wagner Siltstone" early Orellan Orellan
Whitneyan
P3 ap
tr
P4 ap
tr
M2 ap
tr
M3 ap
tr
p4 ap
tra
trp
ml ap
tra
trp
m2 ap
tra
trp
m3 ap
tra
trp
Dp4 ap
tra
trp
il ap
tr
II ap
tr
2.50-2.62
2.73-3.10
or
2.50-2.62
2.73-3.10
2.31-2.34
2.75-2.78
2.36-2.41
2.85-2.87
2.54
3.05
2.70-2.73
2.89-2.94
2.55
2.02
2.30
2.70
2.70
2.74
or
2.70
2.70
2.74
2.65-2.89
3.30-3.50
2.96
3.08
3.00-3.08
2.06-2.22
2.28-2.52
2.67-3.07
2.36-2.58
2.60-2.80
3.11-3.36
2.86-2.95
2.72-3.28
3.18-3.47
2.88-3.04
2.68-2.85
1.20-1.26
1.27-1.22
2.36
2.76
2.17-2.31
2.90-3.00
2.17-2.30
2.90-2.98
2.57-2.58
2.56-2.61
2.12
1.77
2.28
2.15-2.20
1.89-1.97
2.37-2.55
2.28-2.32
2.25-2.57
2.57-2.75
2.86
2.31-2.44
1.97-2.12
1.2
1.2
2.6-2.7
3.0
2.4-2.7
2.9-3.2
2.65
3.07
2.56
2.34
2.40
1.36
1.86
3.13
1.84
2.61
1.92
2.66
2.47
2.43
2.70
2.71
2.72
2.79
3.37
2.75
2.64
3.04
1.98
2.81
1.68
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
(Table 3). Lower teeth of Cedromus from the "Brown
Siltstone," discussed below, are somewhat larger than
the other species.
Martin's (1973) dissertation referred the relatively
large rugose-toothed sciurid from the Wildcat Ridge
"Gering A= Brown Siltstone" to a new species of
Protospermophilus; however this material has never
been formally described. Comparison of this material,
along with "sciurid" teeth from the younger Gering For-
mation, with the more diagnostic skull from Wagner
Quarry and other identified Cedromus material in the
University of Nebraska State Museum collections indi-
cates that these teeth can be included in Cedromus.
The lower cheekteeth have a reduced metalophulid II
and hypolophulid, which expands and flattens the talonid
basin, and the teeth are more quadrate in occlusal out-
line with a flatter, broader surface in comparison to C.
wilsoni (Korth & Emry 1991). The lower ml and m2
also show the presence of four roots, unlike C. wardi
(e.g. UNSM 81086, L ramus with m3), but similar to
Cedromus sp. material (UNSM 81033 Lm2-m3) from
the Whitney Member of the Brule. The Wildcat Ridge
Cedromus specimens may represent C. savannae, but
there is not sufficient material to make a definitive as-
signment at this time.
Martin (1973) described another, much smaller
sciurid from the Wildcat Ridge region that he assigned
to Miospermophilus. This material is referable to the
Cedromurinae because it has the specialized masseteric
structure developed on the ramus (UNSM 14993, L ra-
mus with p4-ml). It has the same dental morphology
described for Oligospermophilus douglassi (see Korth
1981, 1987) except that it is smaller, the hypolophid is
reduced or absent, and the mesostyle is minute (UNSM
11522, R P4). This sample represents a new species of
Oligospermophilus that extends the range of the ge-
nus into the earliest Arikareean.
Storer (2002) and L. J. Macdonald (1972) both
described a large sciurid from the late early Arikareean
(Ar2) that has dental characters similar to both Cedromus
and Protospermophilus (Black 1963). Detailed study
of this material, and the earliest Arikareean Cedromus,
may show that either Protospermophilus replaces
Cedromus or that the Cedromus lineage continues into
the late early Arikareean (Ar2).
Observation of all the Cedromus material from
stratigrapically oldest to youngest provides evidence
for a lineage in North America beginning in the early
Orellan and ending in the early Arikareean (Arl or
Ar2). There is a trend in the cheek teeth to become
more quadrate through reduction of transverse width
in the upper molars and expansion of the transverse
width in lower molars. Except for C. wilsoni, which
enlarges the hypolophulid (Korth & Emry 1991), there
is also a trend in reduction of lophules in the lower
molars.
Minjin (2004) described a new genus of sciurid,
Kherem hsandgoliensis, from the early Arikareean
equivalent (31.5- 28 Ma Shandgolian) Hsanda Gol For-
mation. This sciurid is distinguished from Cedromus by
having an incomplete metalophid (metalophulid II), a
reduced hypolophid, and slightly smaller size than C.
wilsoni. This description would match the "Brown Silt-
stone" and Gering Cedromus in morphology. I have not
proposed formal synonymy here but recommend fur-
ther investigation into the similarity of these taxa.
Additional Cedromus sp. Referred Specimens.-
Mo-119 (Swisher 1982, Gering A= "The Brown Silt-
stone"): UNSM 14993, L p4-ml; UNSM 14958, R Ml
or 2; UNSM 14960, R m2; UNSM 14959, R m2; UNSM
11621, L M2; UNSM 11631, L m3; UNSM 11623, L
M2; UNSM 11650, R dp4; UNSM 11628, R mandible
fragment w/incisor; UNSM 11651, R M3; UNSM 11626,
L p4; UNSM 11640, L ml; UNSM 11553, R ml. Mo-
108 (Reddington Gap): UNSM 11728, L ml. Mo-107
Anthill #1 (Swisher 1982, Gering B): UNSM 81219, R
Ml or 2; UNSM 81218, R ml or 2. Mo-107 Anthill #2
(Swisher 1982, Gering C): UNSM 81214, R Ml or 2;
UNSM 81216 R p4.
Genus NOTOTAMIAS Pratt & Morgan 1989
NOTOTAMIAS sp.
Figures 10M; 13B; Table 3
Referred Specimen.-UNSM 123293, L ramus
fragment with ml-3.
Discussion.-Identification of this ramus is based
on comparison to the more complete and diagnostic
material of this new species in the Ridgeview If. These
specimens, together with the Wagner Quarry mandible,
show the diagnostic criteria for Nototamias as defined
by Pratt & Morgan (1989) and reviewed by Korth
(1992:100) for N. quadratus from the McCann Canyon
If. These include: absence of the mesoconid, reduction
of trigonid or anterolabial groove, presence of metastylid,
and two-rooted lower molars. I defer formal description
of this new species to those researchers describing the
Ridgeview If.
Family CASTORIDAE Gray 1821
Subfamily AGNOTOCASTORINAE Korth & Emry
1997
Genus AGNOTOCASTOR Stirton 1935
AGNOTOCASTOR sp.
Figure 10E
Referred Specimen.-UNSM 123295, R p4.
Discussion.-Because cranial features rather than
dental features define the various genera and species of
fossil Castoridae (Korth 1994a), no specific determina-
tion is attempted here from only a single tooth. How-
ever, the relatively low crown height and the complexity
of the fossettids in this tooth easily separate it from
Palaeocastor and assign it to Agnotocastor.
Agnotocastor first appears in the Chadronian and last
occurrs in the Great Plains at ~ 27.5 Ma (Xu 1996), but
persists longer in the Gulf Coast (Hayes, 2000). Mea-
surements: ap = 3.74, tra = 2.26, trp = 2.80
Subfamily PALAEOCASTORINAE Martin 1987
Genus PALAEOCASTOR Leidy 1869
PALAEOCASTOR sp.
Figure ION; Table 3
Referred Specimens.-UNSM 123284, R Ml or
2; UNSM 123294, cheektooth; F:AM 141243, R M3;
F:AM 141244, lower incisor; F:AM 141245, R p4; F:AM
141246, partial maxilla with L P4-M3 and R M1-M2.
Discussion.-The lower incisor has a flattened
anterior surface and the cheektooth fossette pattern is
simple, both characters diagnostic of the
Palaeocastorinae. In size the maxilla more closely re-
sembles that of P nebrascensis than that of the other
earliest Arikareean Palaeocastor species, P.
pennisulatus, recognized by Xu (1996). The actual num-
ber and diagnosis ofpalaeocastorine genera is still some-
what controversial (Korth, 1994a: 147, lists four species
of Palaeocastor) and like Agnotocastor differences in
species are primarily based on cranial characters. There-
fore, with such meager material from Wagner Quarry,
no species assignment is attempted here.
Family HETEROMYIDAE Gray 1868
Genus PROHETEROMYS Wood 1932
PROHETEROMYS cf. P NEBRASKENSIS Wood
1937
Figure 13A; Table 3
Type.-MCZ 5051, L ramus with p4-m3.
Type Locality.-Upper Brule Formation,
Protoceras beds, below "top ash," Jail House Rock,
Morrill County, Nebraska, late Whitneyan.
Referred Specimen.-UNSM 123281, R ramus
with incisor, p4, m3.
Discussion.-This mandible has a simple four-
cusped p4 with no anteroconid or cingula. The Wagner
Quarry ramus is larger than another common early
Arikareean Proheteromys, P fedti (Bailey 2004). It is
similar in size and morphology to the "type" of P bumpi
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
and P nebraskensis, although P bumpi has a more
complex p4. The dental morphology matches the de-
scription of P. nebraskensis by Wood (1937), although
the m3 is more elongate and wider (Table 3). Korth and
Bailey (pers. comm., 2004) are in the process of revis-
ing this genus and species based on the substantial ma-
terial of "Proheteromys" nebraskensis found in the
Ridgeview If (over 1000 specimens).
Family CRICETIDAE Rochebrune 1883
Subfamily EUCRICETODONTINAE Mein &
Fruedenthal 1971
Genus LEIDYMYS Wood 1936
LEIDYMYS BLACK Macdonald 1963
Figure 10; Table 3
Eumys black Macdonald 1963
Type.-SDSM 5574, R ramus with ml-3.
Type Locality.-SDSM V5410, Sharps Formation,
early Arikareean.
Referred Specimens.-UNSM 123287, R ramus
with ml-m3; F:AM 141248, R maxilla with M 1-3.
Range.- South Dakota, Wyoming, Nebraska,
early early Arikareean (Arl).
Discussion.- For a complete description, see
Martin (1980), and for species comparisons, see Will-
iams & Storer (1998). Comparison with the extensive
material described by Martin (1980) from the Gering
Formation confirms the identity of this ramus. The ab-
sence of non-planar wear and low crown height sepa-
rates this taxon from other cricetids such as Geringia
below. Martin (1980:20) diagnosed the taxon as having
cuspidatee and terraced" molars.
Genus GERINGIA Martin 1980
GERINGIA MCGREGORI Macdonald 1970
Figures 10F-H; 13D-E; Table 3
Paciculus mcgregori Macdonald 1970
Type.-LACM 9271, partial cranium with 11, M l -
M3.
Type Locality.-LACM 1959, Sharps Formation,
early Arikareean.
Referred Specimens.-UNSM 123283, L ramus
with ml-3; UNSM 123286, R ramus with il, ml-3, from
"upper fossil channel."
Discussion.-For a detailed description, see Mar-
tin (1980: 25-30). The two specimens found at Wagner
Quarry and the "upper fossil channel" do not differ from
the material referred to Geringia mcgregori by Martin
(1980) from the "Gering" of the Wildcat Ridge; nor do
they differ from the substantial Geringia material in the
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
Ridgeview If. Geringia is the most abundant rodent in
the Gering Formation (Martin 1980) and is very com-
mon in the Ridgeview If (Bailey 2004). Martin discussed
Geringia as having a variable size and morphology which
the two rami (Fig. 10F-G; Table 3) from Wagner Quarry
demonstrate. The preserved incisor (UNSM 123286; Fig.
1 OH) has the single ventral ridge typical (Martin 1980:25;
40; Fig. 26) of the genus.
Williams & Storer (1998) described a sample of
Geringia from the Kealey Springs If that they referred
to G gloveri, a species named by Macdonald (1970:51-
52) from the "Monroe Creek" Formation of South Da-
kota. The Kealey Springs sample is intermediate in size
between G gloveri and G mcgregori. Both Martin
(1980) and Williams & Storer (1998) brought into ques-
tion the validity of G gloveri, because the two species
only differ slightly in size; but neither formally synony-
mized the two. There appears to be a morphocline in
size from the first record of G mcgregori at the begin-
ning of the Arikareean (Arl) to the last appearance of
the genus, G gloveri, at the beginning of the early late
Arikareean (Ar2).
Order LAGOMORPHA Gidley 1912
Family LEPORIDAE Gray 1821
Genus PALAEOLAGUS Leidy 1856
PALAEOLAGUS HYPSODUS Schlaikjer 1935
Figure 1 OK; Table 3
Type.-MCZ 2889, R maxillary with P3-M2.
Type Locality.-NW 1/4, Section 21, Township 20
North, Range 62 West, Goshen County, Wyoming, 46m
(150') above Brule contact; early Arikareean.
Referred Specimen.-F:AM 141247, L ramus with
p3-m3.
Discussion.-The ramus and dentition are similar
in size to both P philoi and P hypsodus, both known
from early Arikareean localities (e.g. MacDonald 1963,
1970). According to Dawson (1958), P philoi develops
a single reentrant on p3 with wear and the m3 maintains
a double column "hourglass" shape through extended
wear. The Wagner specimen has an "hourglass" p3 with
both a lingual and labial, cement-filled reentrant unlike
P philoi and the m3 has merged into a single column
with a labial reentrant (Fig. 10K). Both of these charac-
ters are consistent with P hypsodus (Dawson 1958).
PALAEOLAGUS PHILOI Dawson 1958
Figure 10L
Type.-SDSM 53389, R maxilla with P2-M2.
Type Locality.-SE 1/4, Section 31, Township 40
North, Range 43 West, Lower Rosebud beds; early
Arikareean.
Referred Specimen.-UNSM 48452, L p3.
Description.-The p3 is slightly worn with two
transverse lophs. The anteroloph is divided into 2 cusps
by a shallow, cement-filled anterior groove, which ex-
tends minimally down the anterior face. The posteroloph,
or talonid, is divided from the anteroloph by a distinct
labial, cement-filled reentrant that would enlarge and
extend more lingually across the tooth with wear. On
the labial side there is a shallow reentrant that would be
quickly lost with wear. Dimensions: ap = 1.82 (at cusp),
2.02 (at base), tr = 2.06.
Discussion.-Dawson (1958: 30, Fig. 13) described
an unworn p3 of Palaeolagus philoi that, with slight
wear, would produce the morphology seen in UNSM
48452. With continued wear this tooth would show a
single buccal reentrant unlike the p3 described above
for P hypsodus. Megalagus cf. primitivus, also de-
scribed by Dawson (1958:17) from the early Arikareean,
has a p3 with similar morphology to the Wagner tooth
but is considerably larger in transverse size (e.g.: ap =
2.0-2.1, tr = 2.6-2.8). In size UNSM 48452 is closest in
size to P philoi (e. g.: ap = 1.9-2.5, tr = 1.9-2.2) de-
scribed by Dawson (1958).
Genus MEGALAGUS Walker 1931
MEGALAGUS cf. M. PRIMITIVUS
Figure 100
Referred Specimens.-UNSM 123294, lower
molar.
Description.-There is a lingual enamel connec-
tion between the trigonid and talonid. The anterior enamel
margin of the talonid is thin and weakly crenulated. Di-
mensions: ap = 2.80, tra = 2.92, trp = 2.65.
Discussion.-This tooth is referred to Megalagus
based on its larger size in
comparison to Palaeolagus hypsodus and P.
philoi. Also, typical of Megalagus is the lingual con-
nection between the trigonid and talonid, as well as the
weak crenulations in the anterior margin of the talonid
(Hayes 2000). This tooth matches the size range for
Megalagus primitivus given in Dawson's (1958) de-
scription of the species, but this single specimen pre-
cludes a definite referral.
Order CARNIVORA Bowdich 1821
Division ARCTOIDEA Flower 1869
Family AMPHICYONIDAE Trouessart 1885
Genus PARADAPHOENUS Wortmann & Matthew
1899
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
Figure 13. Wagner Quarry local fauna: rodents, Nimravus, and Miohippus. A, UNSM 123281, Proheteromys cf P
nebrascensis, R ramus with il, p4, m3, lingual view. B, UNSM 123293, Nototamias sp., L ml-3, oblique occlusal
view. C, UNSM 123285, Downsimus chadwicki, L ramus with p4-m3, occlusal view. D, UNSM 123286, Geringia
mcgregori, R ml-m3, lateral view, upper fossil channel.; E, UNSM 123286, Geringia mcgregori, R ml-m3, occlusal
view, upper fossil channel. F, UNSM 123400, Alwoodia cf A. magna, L P4, occlusal view. G-H, UNSM 123242,
Nimravus brachyops, L juvenile ramus with dc, dp3-dp4; G, medial view; H, lingual view, showing unerupted p4-ml;
J, UNSM 123241, Miohippus sp., L juvenile mandible and symphysis with p2-m3, ml-m2 erupted, lateral view. A-F,
scale bars = Imm; G-J, scale bars = 10mm.
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
PARADAPHOENUS TOOHEYI Hunt 2001
Referred Specimen.-UNSM (field #) 6002-92, L
mandible w/ p3-m2.
Description and Discussion.-Hunt (2001) de-
scribed a new species of Paradaphoenus and desig-
nated the mandible (UNSM [field #] 6002-92) referred
above from Wagner Quarry as the holotype. Additional
material from White River sediments in Nebraska
(UNSM 26130) and a maxilla (LACM 21649) from the
Sharps Formation of South Dakota was also referred to
this species. He demonstrated that P tooheyi from the
Whitneyan to earliest Arikareean was an intermediate
form between the Orellan P minimus and the late early
to medial Arikareean P cuspigerus.
Family CANIDAE Gray 1821
CANIDAE indet.
Referred Specimen.-UNSM 48450, ramus with
ml talonid, m2, and m3 alveolus
Discussion.- In size, this jaw compares with early
Arikareean Archaeocyon and Otarocyon (Wang et al.
1999), but a generic determination is not possible due to
the poor condition of this specimen.
Suborder FELIFORMIA Kretzoi 1945
Family NIMRAVIDAE Cope 1880
Genus NIMRA VUS Cope 1879a
NIMRAVUS BRACHYOPS (Cope) 1878
Figure 13G-J; Table 5
Machairodus brachyops Cope 1878
Hoplophoneus brachyops Cope 1879a
Lectotype.-AMNH 6935, partial R ramus.
Range.-Whitneyan to late early Arikareean (Ar2)
of Great Plains and Pacific coast.
Referred Specimens.-UNSM 123242, juvenile R
jaw dc, dp3-4, unerupted p4-ml.
Description.-Symphyseal region is
anteroposteriorly angled and almost flat from symphysis
to canine (Fig. 13G, H). Small mental foramen is lo-
cated below dp3. Masseteric fossa is deep and extends
anteriorly to position approximately ventral to ml. Al-
veolus is for single-rooted dp2. The dp3 is elongate and
transversely compressed with central ridge from tren-
chant anterior cusp along principal cusp to cuspate (rela-
tively broad) posterior cusp. The dp4 has small meta-
conid present at lingual base of protoconid. Ridge joins
metaconid to trenchant, posterolabialy directed hypo-
conid. Paraconid and protoconid transversely com-
pressed with protoconid taller than paraconid and widely
separated by deep carnassial notch. Weak serrations
present on anterior ridge of protocone. The p4 and ml
is unerupted. Principal cusp is only visible part of p4.
Weak serrations occur along posterior and anterior ridges
of cusp. Principal cusp of p4 is similar in size to paraconid
ofml. The ml has a slit-like deep carnassial notch. Pro-
toconid and paraconid are similar size, transversely com-
pressed with weakly serrated edges. Protoconid is taller
than paraconid. Small alveolus is located directly behind
the ml that could have held unerupted m2. Measure-
ments for specimen not included in Table 4 include: depth
of horizontal ramus at alveolar margin of dp4 = 20.16;
length of masseteric fossa -= 30.50; length of diastema =
9.24.
Discussion.-Martin's (1998) review of the
nimravids recognizes three genera in the early
Arikareean, Nimravus, Pogonodon, and Eusmilus. This
differs from Bryant's (1996) earlier work that also in-
cluded Hoplophoneus dakotensis. Although Martin
referred this taxon to Eusmilus, generic referral of this
taxon is controversial (see Bryant 1996: 465). Eusmilus
is now known to be a very small nimravid (Hunt, pers.
comm., 2004), and too small to correspond to the Wagner
Quarry mandible. The ml of Eusmilus has also lost the
talonid. In size the Wagner Quarry mandible is closest
to Nimravus and Pogonodon. H. dakotensis is con-
siderably larger.
Referral of this juvenile dentary to Nimravus, and
its only species, N. brachyops (Toohey 1959), is based
on several factors. Adult Nimravus is, in part, distin-
guishable from Pogonodon because Pogonodon has
a ventral symphyseal flange that does not appear to be
developing in the Wagner Quarry mandible. Nimravus
has a continuous ventral mandibular border that is ven-
trally concave, which matches the Wagner Quarry speci-
men. Pogonodon has a ventrally convex mandible mar-
gin. Finally, the extension of the masseteric fossa is a
useful diagnostic characteristic. The masseteric fossa
extends anteriorly to below the ml in Nimravus; erup-
tion of the ml in the Wagner specimen would be above
the fossa. Pogonodon has a masseteric fossa that ex-
tends only to behind the posterior margin of the ml un-
like UNSM 123242.
Order PERRISSODACTYLA Owen 1894
Family EQUIDAE Gray 1821
Genus MIOHIPPUS Marsh 1874
MIOHIPPUS sp.
Figure 13K; Table 5
Type Species.-Miohippus annectens Marsh
1874.
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
Table 5. Dental measurements for Nimravus brachyops, Miohippus sp., Leptauchenia major, Pseudolabis
dakotensis, Nanotragulus loomisi. Specimens are from Wagner Quarry If unless otherwise stated. a= approximate
measurements.
Nimravus
brachyops UNSM 123242
ap dc 5.74 dp3 9.25 dp4 15.22 ml a23.80
tra 4.47 2.81 4.31
trp 3.47 3.80
AMNH 6930 holotypee) John Day, OR ap ml 24.32
AMNH 6936 John Day, OR ap ml 22.33
UNSM 2509-59, MO-103, Morrill, Co., NE ap ml 24.99
Miohippus sp. UNSM 123241
p2 p3 p4 ml m2 m3
ap 15.33 15.30 13.70a 14.91 13.98 17.07a
tra 8.60 9.80 10.08a 10.40 10.40
trp 8.80 11.25 10.33 9.60
Leptauchenia
major F:AM141385
P2 P3 P4 MI M2 M3
ap 5.42 5.42 5.62 9.25 12.48 14.05
tr 4.41 4.41 8.42 10.64 12.38 12.90
F:AM141384 UNSM 123280
ml m2 m3 dp4 ml
ap 10.47 12.84 14.90a 12.16 11.30
tra 6.74 8.41 7.31a 4.16 5.99
trp 7.63 9.09 5.85 6.83
Pseudolabis
dakotensis F:AM141372
ap dP3 10.48 dP4 13.71 MI 14.25 M2 16.54
tr 4.14 8.14 10.85 13.40
F:AM 41814 Muddy Creek, Lusk, WY
P2 P3 P4 Ml M2
ap 10.17 12.75 13.64 15.26 16.97
tr 3.74 7.27 10.15 12.61 13.60
Nanotragulus
loomisi F:AM 141242
P2 P3 MI M2 M3
ap 1.83 3.79 4.09 5.76 7.07
tr 1.41 2.87 5.47 5.88 5.93
UNSM 48449
ap p4 4.70 ml 5.30 m2 5.72
tra 2.40 3.05 3.71
trp 3.52 4.16
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
Type Locality.-John Day Formation, Oregon.
Referred Specimens.-UNSM 123238, magnum;
UNSM 123241, juvenile L mandible with R p2-m3, ml -
2 erupted; UNSM 123401, R metatarsal III; UNSM
123402, R proximal phalanx.
Description.-Only the alveolus ofpl is preserved.
The p2-m3 have weak labial cingula discontinuous around
labial margin. Cingula is developed only on anterior,
hypoflexid valley, and posterior surfaces. No lingual cin-
gula is present. Posterior cingulum merges with small
hypoconulid. Metaconid and metastylid distinctly
twinned, high, equal in height to entoconid and other prin-
cipal cusps. Lophids is low in comparison to cusps.
Metalophid is confluent with metastylid only after wear.
The m3 has large heel and metalophid separated from
the metastylid.
Discussion.-Prothero & Shubin (1989) diagnosed
Miohippus on the basis of an articular surface devel-
oped between the cuboid and third metatarsal. UNSM
123401, a right third metatarsal, has the cuboid facet
and would be of appropriate size to correspond to the
mandible. A proximal phalanx that may be associated
with the metatarsal (UNSM 123402) is also of appropri-
ate size to be referred to Miohippus rather than
Mesohippus (O'Sullivan 2003; Fig. 7).
When Prothero & Shubin (1989) reviewed the Oli-
gocene horses, they listed five species of Miohippus in
the early Arikareean. The majority of these species are
diagnosed on morphology of the skull, upper dentition, or
size. Comparison of the Wagner Quarry mandible and
postcranials with their measurements (Table 10.3, p 151
and Table 10.4, p. 158-159) indicates that the Wagner
horse is closest in size to the type of M. intermedius
(AMNH 1196, from the late Whitneyan Poleslide mem-
ber of the Brule Formation, Protoceras channels) and
type of M. annectens (YPM 12230, from the early
Arikareean John Day Formation, Turtle Cove member
between Picture Gorge Ignimbrite and Deep Creek
Tuff). Miohippus equinanus and M. obliquidens are
20-25% smaller, M. gidleyi is 20% larger. Miohippus
annectens is 10% larger than the Wagner Miohippus.
Referral to M. intermedius is not conclusive however,
because the Wagner Miohippus has a more elongate
and cuspate p2, and the metalophid is more confluent
with the metastylid.
In the most recent summary of the Equidae,
MacFadden (1998) included 7 named species of
Miohippus and stated that a complete revision is still
needed.
Family RHINOCEROTIDAE Owen 1845
Subfamily DICERATHERIINAE Dollo 1885
Genus DICERATHERIUM Marsh 1875
Comment.-Throughout the Whitneyan and most
of the Arikareean in the Great Plains, Diceratherium is
the single rhinocerotid present (Prothero et al. 1989) until
the immigrant, Menoceras, appears in the late
Arikareean. Subhyracodon is on average smaller, with
less molarized premolars, than Diceratherium and, while
found in the Chadronian through Orellan of the Great
Plains, is known only from the west coast regions in the
early Arikareean (Prothero 1998). At times there have
been at least 6 proposed species of Diceratherium from
the John Day region in Oregon and the Great Plains.
Albright (1999) briefly reviewed Diceratherium
and the distinctions between species. He synonymized
D. cuspidatum with D. annectens and questioned the
validity of D. gregorii, a taxon Peterson (1920) erected
for material from the Great Plains and was later sup-
ported by Green (1958) and Macdonald (1963, 1970).
Prothero's (1998) summary of the Rhinocerotidae did
not recognize D. gregorii as a separate species.
Prothero (1998) stated that two parallel lineages
of Diceratherium exist throughout the late Whitneyan
and Arikareean of the Great Plains: a large species, D.
armatum and a smaller species, D. annectens. A third
relatively large species, D. niobrarense occurs in the
later Arikareean and early Hemingfordian. Albright
(1999) proposed 3 valid Diceratherium species, D.
annectens, D. armatum, and D. niobrarense. Prothero
also referred a Whitneyan species, Subhyracodon
tridactylum, to Diceratherium.
The two early Arikareean species of
Diceratherium differ chiefly in size; the smaller spe-
cies is D. annectens and the larger species, D. armatum.
Within each species considerable sexual dimorphism has
been observed. The large Arikareean sample from 77
Hill Quarry near Lusk, Wyoming preserves male and
females of both D. annectens and D. armatum
(Prothero et al. 1989) and this sample has provided com-
parative material for this study as well as others (Albright
1999).
DICERATHERIUMANNECTENS (Marsh) 1873
Figure 14A-B, E, J; Table 6
Rhinoceras annectens Marsh 1873
Diceratherium nanum Marsh 1875
Diceratherium cuspidatum Troxell 1921
Type.-YPM 10001, L upper premolars with as-
sociated incisor.
Type Locality.-"lower to middle John Day" For-
mation, Oregon (Peterson 1920).
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
Figure 14. A-K, Diceratherium. A, F:AM 141374, D. annectens, R M1-M2, occlusal view, Wagner Quarry. B,
UNSM 123233, D. annectens, L maxilla with P1-3, oblique occlusal view, Wagner Quarry. C-D, astragalus compari-
son. C, AMNH 112185, D. annectens, Schomp Ranch, basal ?Gering Fm, Sioux Co., NE; D, UNSM 123230, D.
armatum, Wagner Quarry. E-F, uniform comparison. E, UNSM 123231, D. annectens, Wagner Quarry; F, AMNH
112185, "D. annectens", Schomp Ranch, basal ?Gering Fm, Sioux Co., NE. G-H, scaphoid comparison. G, UNSM
123229, D. armatum, Wagner Quarry; H, AMNH 112185, D. annectens, Schomp Ranch, basal ?Gering Fm, Sioux
Co., NE. J-K, calcaneum comparison. J, UNSM 123228, D. annectens, Wagner Quarry. K, F:AM 141386, D.
armatum, 1m above Wagner Quarry. Scale bars = 10mm.
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
Referred Specimens.-F:AM 141375, R pl-p3;
F:AM 141374, R M1-M2; UNSM 123228, calcaneum;
UNSM 123233, L maxilla w/Pl-3; UNSM 123231, un-
ciform; UNSM 123230, R astragalus; trochlear tr =
68.37; nav-cuboid tr = 71.50.
Discussion.-There are two size groupings of rhino
material in the Wagner Quarry If. Comparison of the
Wagner material within the sample and with complete
material from the 77 Hill Quarry mentioned above illus-
trates this. Comparison of the two calcanea (Fig. 14J-
K) demonstrates the size difference between the two
species and the similar morphology of the two taxa. This
smaller sized rhino material is referred to D. annectens.
The partial maxilla (Fig. 14B) and the uniform (Fig.
14E) are slightly smaller in measurements, but not sig-
nificantly, when compared with D. annectens (Table 6;
Fig.14F). Diceratherium is known to be sexually di-
morphic and the size difference in these two specimens
may reflect the morphology of a smaller female.
DICERATHERIUM ARMATUM Marsh 1875
Figure 14D, G-K; Table 6
Diceratherium lobatum Troxell 1921
Type.-YPM 10003, complete skull with
postcranials.
Type Locality.-"lower John Day" Formation,
Oregon (Peterson 1920).
Referred Specimens.-F:AM 141386, calcaneum,
Im above Wagner Quarry; UNSM 123229, scaphoid;
UNSM 123432, vertebrae; UNSM 123433, distal femur;
UNSM 123420, thoracic vertebrae; UNSM 123421, L
metatarsal IV: ap = 15.7cm, 22.79cm distal end width;
UNSM 123426, juvenile partial occipital condyle: 52mm
width; UNSM 123416, navicular; UNSM 123417, un-
gual phalanx: tr = 31.8, ap = 39.08 ; UNSM 123418,
juvenile proximal phalanx; UNSM 123434, L juvenile
ulna; UNSM 123422, partial lower molar.
Discussion.- The larger rhino postcranial mate-
rial is referred to the larger Diceratherium species. Fig-
ure 14G and 14H is a comparison between a Wagner
scaphoid and a D. annectens scaphoid from the early
Arikareean, Schomp Ranch locality of Sioux County,
Nebraska. Figure 14C and D also show the size differ-
ence, but show a similar morphology of small Gering
Formation D. annectens and large Wagner astragali.
The large Diceratherium calcaneum (Fig. 14K) is the
only identifiable fossil found outside of Wagner Quarry
and the "upper fossil channel" (Fig. 6)
Order ARTIODACTYLA Owen 1848
Family ENTELODONTIDAE Lydekker 1883
Table 6. Upper dental measurements for various Diceratherium species. (Compiled from
Albright 1999.)
author's measurements;
Wagner Diceratherium D. annectens D. armatum "D. gregorii"
UNSM annectens AMNH YPM 10003 AMNH 12933
123233 YPM 10001 7324 (type) Sharps Fm
(type) SD
P1 ap 20.4 19.0 29.0 21.0
tr 14.5 17.2 17.0 25.5 20.0
P2 ap 19.0 23.2 24.0 32.0 26.0
tr 24.2 34.3 28.0 39.5 32.0
P3 ap 22.35 27.5 28.0 37.0 31.0
tr 29.24 34.3 35.0 46.0 44.0
Wagner
F:AM
141374
M 1 ap 37.1 35.0 48.0 38.0
tr 39.4 41.0 53.0 45.0
M 2 ap 41.4 40.0 54.0 45.0
tr 40.6 41.0 55.0 47.0
ENTELODONTIDAE indet.
Referred Specimens.-UNSM 123457, ungual
phalanx; UNSM 123458, thoracic vertebrae; UNSM
123455, R scapula; UNSM 123456, L scapula; UNSM
123439, L ectocuneiform.
Discussion.-There are only postcranial remains
known from this taxon in Wagner Quarry. Dinohyus
ranges from the early Arikareean until the early
Hemingfordian (Effinger 1998). Martin (1973) referred
a mandible missing the incisors, canines, and part of the
symphysis (UNSM 1083) to Dinohyus minimus? from
four feet above the Brule Formation- "?Gering" con-
tact, Goshen County, Wyoming. The only other entelodont
reported in the early Arikareean, Archaeotherium
trippensis (Skinner et al. 1968), is from the early to
medial Turtle Butte fauna (Tedford et al. 1987), but it is
known only from cranial material. The two recovered
scapulae, ungual phalanx, and vertebrae, are indistin-
guishable in size and morphology from Dinohyus mate-
rial collected from the Agate waterhole bone bed in the
Nebraska State Museum. However, since there are no
known postcranial remains of A. trippensis to compare
with, and A. trippensis is similar in cranial size to
Dinohyus and much larger than other species of
Archaeotherium (Skinner et al. 1968), referral to this
taxon cannot be ruled out.
Family MERYCOIDODONTIDAE Thorpe 1923
Subfamily DESMATOCHOERINAE Schultz &
Falkenbach 1954
DESMATOCHOERINAE indet.
Figure 15K
Referred Specimens.-UNSM 123240, juvenile L
ulna; UNSM 123235, metapodial MIV; UNSM 123445,
R M1.
Discussion.-Identification of this material was
based on comparison to oreodont material housed in the
UNSM collections. Further comparison was conducted
at the AMNH. Both the ulna (Fig. 12K) and metapodial
agree in size and morphology to a desmatochoerine par-
tial skeleton, F:AM 44936, Desmatochoerus hatcheri,
from the lower Arikaree Group at Muddy Creek, Niobrara
County, Wyoming. This specimen was referred to D.
hatcheri niobrarensis by Schultz & Falkenbach (1954:
191). Desmatochoerines are typical of lower Arikaree
rocks and thus the early to medial Arikareean (Hunt,
pers. comm., 2004).
Genus LEPTA UCHENIA Leidy 1856
LEPTAUCHENIA MAJOR Leidy 1856
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
Figure 15H-J; Table 5
Type.-AMNH 8115, skull and mandibles with
associated postcranials.
Type.-Deep River Beds, Smith Creek Montana.
Range.-Orellan through late early Arikareean
(Ar2) of the Great Plains, Wyoming, and Montana.
Referred Specimens.-UNSM 123279, L maxilla
fragment w/P1-P2; F:AM 141385 L maxilla w/P2-M3,
alveolus for PI; UNSM 123239, L M2; UNSM 123280,
R Dp4-ml.
Discussion.-CoBabe (1996) reviewed the
leptauchenine oreodonts and reduced the total species
to 3: L. decora, L. major, and Sespia nitida. Lander
(1998) listed 4 Leptauchenia species, each with sev-
eral subspecies, and Sespia. CoBabe's (1996) taxonomy
is followed here for the sake of simplicity. Sespia is
separable from Leptauchenia by its extremely hypsod-
ont molars and smaller size. There are two species of
Leptauchenia; L. decora is generally smaller than L.
major, although there is some overlap in size. The major
difference between the two species is that L. decora
has lost its M3. AMNH 472-4294 possesses the M3
and is larger in average tooth measurements than L.
decora; therefore, I have referred the leptauchenine
material to L. major. Leptauchenines are limited in their
occurrence in the central Great Plains to rocks of the
lower Arikaree Group.
Family ANTHRACOTHERIIDAE Gill 1872
Subfamily BOTHRIODONTINAE Scott 1940
BOTHRIODONTINAE indet.
Figures 15A-B, F; 16C; Table 7
Referred Specimens.-UNSM 123222, R calca-
neum; UNSM 123225, radius; UNSM 123226, ulna;
F:AM 141369, R and L mandibles with p2-m3, alveoli
for il-pi; UNSM 123407, juvenile tibia; UNSM 123419,
partial innominate juvenile.
Description.-Mandible and dentition. Symphysis
is elongate, posterior margin below the p2. Anterior den-
tition missing, p2-m3 present on both sides. Large men-
tal foramen is below diastema between p2 and p3.
Masseteric fossa extends to just below crown of m3 on
ascending ramus. Angular process has rounded ventral
margin that extends posteriorly and below ramus. Enamel
on all teeth is rough and cingula rugose. Alveoli show
that incisors increased in size from il to i3. Canine was
oval in shape, transversely compressed. The p2 and p3
have high central cusps, weakly concave on lingual face
and strongly convex on labial face. Anterior cingulum is
not present on pl, although a weak anterior cingulum
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
Figure 15. A-G: Anthracotheres. A, F:AM 141369, Bothriodontinae indet., mandible, Wagner Quarry, lateral view. B-
D, Anthracothere right calcaneum comparison. B, UNSM 123222, Wagner Quarry; C, AM 13005, Arretotherium
leptodus holotypee), "lower Rosebud beds", Shannon Co., SD ; D, F:AM 132053, Arretotherium fricki, Potter
Quarry, Runningwater Fm, Dawes Co., NE. E-G: Anthracothere symphysis comparison, occlusal view. E, AM
13005, Arretotherium leptodus holotypee), old female; F, F:AM 141369, Bothriodontinae indet., Wagner Quarry,
young female; G, F:AM 132054, "Arretotherium", Gering Fm, Goshen Co., WY, old male. H-J: Leptauchenia
major, upper fossil channel- Wagner Quarry section. H, F:AM 141385, L maxilla, labial view; J, F:AM 141384, R
ramus with M2-M3, labial view. K, UNSM 123240, Desmatochoerinae indet., L ulna. L-M: Nanotragulus loomisi.
L, F:AM 141241, R maxilla, occlusal view; M, UNSM 48449, L ml-2, labial view. A-K, scale bars = 10mm; L-M,
scale bars = Imm.
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
Figure 16. Anthracothere mandible comparison, occlusal views. A, F:AM 132055, Arretotherium fricki, Running
Water Fm, Potter Quarry, Sand Canyon, Dawes, County, NE; B, AM 13005, Arretotherium leptodus holotypee),
"Monroe Creek" Fm, Porcupine Butte, Pine Ridge, SD; C, F:AM 141369, Bothriodontinae indet., Wagner Quarry; D,
F:AM 132054, "Elomeryx", Gering Fm, East of Tremain, Goshen County, WY. E, F:AM 132055, "Arretotherium",
"Monroe Creek" Fm, Slim Buttes, Shannon County, SD.
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
Table 7. Comparative lower dental measurements of selected North American anthracotheres with Wagner
anthracothere. (Compiled from author's measurements; Albright, 1999; Macdonald, 1954.) a= approximate measure-
ments.
Wagner Gering Fm "Monroe Arretotherium? A. fricki
F:AM F:AM Creek" leptodus F:AM
141369 132054 F:AM AMNH 13005 132053
female male 32055 (type)
c ap
tr
pl ap
tr
p2 ap
tr
p3 ap
tr
p4 ap
tr
ml ap
tr
m2 ap
tr
diastema
c-p l
pl-p2
p2-m3
p4-m3
12.9-13.5a
8.7a
9.8a
6.3-6.5a
14.4-14.6
6.37-6.8
16.7-17.1
8.7-8.8
18.3-18.5
10.4-10.8
18.42-18.62
12.53-12.57
22.8-23.2
15.6-15.9
35.8-37.1
16.6-17.2
9.54
7.45
125.29
95.32-97.42
20.26
13.37
9.1-9.7
4.7-5.0
13.9-14.3
6.3-6.6
16.95-17.04
7.9-8.4
19.15-19.27
10.2-10.4
17.0-17.1
10.8-12.3
25.4-26.7
14.4-14.8
38.8-39.1
16.0-16.8
11.4-12.5
21.2-22.5
127.26
100.3-102.7
20.3
11.5
19.6
12.3
25.2
14.4
38.4
16.9
130.35
103.54
17.3
8.4
21.32
9.3
18.6
12.95
21.54
13.2
28.55
18
42.6
20.32
13.2
7.1
12.9
7.8
16.7
10.4
16.9
12.7
21.3
37.2
18.02
111.29 92.1
forms on p3 and thicker on p4. The m2 and m3 have
strong anterior cingula. The ml is too worn to distin-
guish anterior cingulum. On p2 lingual cingulum begins
near crest of central cusp and descends towards base.
It thickens slightly, midway to form progressively deeper
valley between it and cutting edge of central cusp in p3
and p4. Lingual cingulum develops small accessory cusp
that enlarges and separates from central cusp and higher
lingual cingulum in p3 and p4. Small flexure in cutting
anterior edge of central cusp in p2 also progressively
enlarges and forms more distinct accessory cusp in p3
and p4. Lingual cingulumjoins with posterior cingulum
at base. Posterior cingulum curves around base, joins
with central cusp ridge, which progressively enlarges in
p3 and p4, and then curves slightly anteriorly before
merging into labial face of the central cusp. Posterior
cingulum forms small basin separate from lingual valley.
The p3 and p4 have increasingly larger talonid heels with
deeper and more expanded basins and valleys.
Lower molars have four high pointed crests with
deep central valley blocked by labial cingulum and
blocked lingually by crista that emerges from base of
metaconid and extends upward to hypoconid. This is
mirrored by crista that extends upward from anterior
cingulum and connects with protoconid. Entoconid and
metaconid is pyramidal in shape with flat faces but trans-
versely compressed. Protoconid and hypoconid is coni-
cal in shape except for a slightly concave lingual sur-
face. The m3 is similar to other molars except that it has
a prominent hypoconulid with an enclosed elongate fos-
sette that extends high on cusp.
Discussion.-Kron & Manning (1998) reported
three genera in the Arikareean: Elomeryx,
Arretotherium, and Kukusepasutanka. Kukusepasu-
tanka is clearly separable from the Wagner
anthracothere based on its much larger size and unusual
morphology (see Macdonald 1956). Separation of
Elomeryx from Arretotherium based on morphological
characters of the lower dentition and mandible is more
difficult. There may be transitional forms in the early
Arikareean because Arretotherium is thought to be de-
rived from Elomeryx (Macdonald 1956; Macdonald &
Martin 1987). Taxonomy of these two genera is based
on characters of the upper dentition and skull rather than
the lower dentition or jaw (Macdonald 1956; Kron &
Manning 1998). Elomeryx is distinguished from
Arretotherium by the presence of a paraconule on the
upper molars.
Albright (1999) described anthracothere material
from the late Arikareean Toledo Bend If that he referred
to Arretotherium acridens. The upper molars lacked
the paraconule of Elomeryx. He also confirmed the re-
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
ferral of the problematical early to medial Arikareean
"Ancodon" leptodus to Arretotherium. Macdonald
had at first (1956) declared the name a nomen vanum
but later (1963) suggested it be placed in Arretotherium
based on its age. The type specimen of A. leptodus,
(American Museum 13005, from the Arikareean lower
Rosebud beds, Porcupine Butte, Pine Ridge, South Da-
kota) has upper molars that are too worn to determine
the absence of the paraconule. Albright described a skull
(F:AM 132055) that is close in morphology to the type
skull of A. leptodus, collected from the same area, that
shows the absence of the paraconule and therefore ar-
gued that this anthracothere sample should be included
in Arretotherium.
One of the characters listed under Macdonald's
(1956) and Kron & Manning's (1998) diagnoses for
Arretotherium is lack of diastemata. They do not state
if this applies to the upper dentition or the lower. The
type of A. fricki (UNSM 5764) has a significant di-
astema between P1 and C (15.5 mm). The material that
Albright (1999) referred to A. acridens shows lower
diastemata of variable but significant lengths (c-p 1: 7.1-
15.0; pl-p2: 14.0-32.5). The type skull of A. leptodus,
AMNH 13005 also has a short diastema between the
upper canine and PI (8.5) and a longer diastema be-
tween pl-p2 (18.30-19.36).
Albright considered this variation to be a conse-
quence of sexual dimorphism. Macdonald & Martin
(1987) also described a sample of Arretotherium that
exhibited considerable sexual dimorphism. Figure 15E-
G is a comparison of three anthracothere jaw symphy-
ses that clearly demonstrate sexual dimorphism in early
Arikareean anthracotheres as well, based on size of the
canines. Figure 15E is an older female, the type of A.
leptodus; the Wagner jaw (Fig. 15F) is a younger fe-
male; and a jaw (Fig. 15G) showing much larger ca-
nines is an older male from the Gering Formation. The
degree of sexual dimorphism and relatively unusual slow
eruption of the molars displayed by anthracotheres (ml
is almost completely worn before wear begins on m3-
see Fig. 16) makes it difficult to distinguish any of these
species on dental size. Table 7 compares several speci-
mens of anthracotheres along with the Toledo Bend
sample. There are no clear divisions in size among the
Arikareean mandibles when males and females are
present in the sample. Elomeryx from the White River
Group are slightly larger and the Hemingfordian A. fricki
are slightly smaller. There is some evidence that sym-
physeal splay becomes more pronounced in younger taxa
(Fig. 16) or this may be a function of increasing ontoge-
netic age. The Wagner jaw (Fig. 16C), although some-
what crushed, shows a smaller symphyseal splay than
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
the more dentally worn type of A. leptodus (Fig. 15B),
which in turn shows a lesser splay than an even more
dentally worn individual of A. fricki (Fig. 15A) with a
very broad splay.
There is undescribed anthracothere material from
the lower Arikaree Group (e.g. F:AM 132054, Fig. 16D)
collected east of Tremain, Wyoming, that is of a similar
size and morphology as the Wagner Quarry material,
but unfortunately there were no upper teeth or skulls in
this material for comparison. The overall character of
the Wagner mandible and other early Arikareean man-
dibles in comparison to Elomervx from the White River
Group is that Elomeryx is more robust with slightly lower
crowned teeth than the early Arikareean sample. On
the other hand, comparison of A. acridens and A.
leptodus with A. fricki also shows that these earlier
forms are more robust. In dental size (Table 7) and
morphology of the cheekteeth (Fig. 16) there are no sig-
nificant differences. Figure 15, B-D, compares calca-
nea among the Wagner Quarry anthracothere, the type
of A. leptodus, and A. fricki from the Hemingfordian.
The Wagner Quarry calcaneum is similar in morphology
to A. leptodus, but slightly more robust. A. fricki is simi-
lar in morphology to A. leptodus but slightly more grac-
ile.
The Wagner anthracothere and those of the early
Arikareean of the Hartville uplift, and the Gering For-
mation of the Wildcat Ridge may be transitional between
Elomeryx of the Whitneyan and "medial" to later
Arikareean Arretotherium. The morphology of the teeth
ofArikareean anthracotheres is more gracile with higher
crowned cheek teeth than Elomeryx from the Whitneyan
but the lineage remains conservative with few modifi-
cations in lower dentition.
The trend in the literature (Kron and Manning,
1998; Tedford et al., 2004) is to consider the early
Arikareean anthracotheres closer to Elomeryx. Tedford
et al. (2004) lists Arretotherium as having its first ap-
pearance in the late early Arikareean (Ar2) and
Elomeryx as having its last appearance in the early early
Arikareean (Arl). Macdonald (1970) named a new spe-
cies of Elomeryx, E. garbanii, found near the top of
the Sharps Formation and also commented that lower
cheek teeth previously referred to Arretotherium from
the Sharps might also belong to Elomeryx because the
referral to Arretotherium was only based on stratigraphic
position. Swisher (1982) questionably reported Elomeryx
from the Gering of the Wildcat Ridge, based on a partial
ramus. Hoganson et al. (1998) reports Elomeryx
armatus from the early Arikareean of North Dakota. A
more conservative approach is taken here: without the
definitive upper molars for comparison, the Wagner
material is not referred to either genus. Macdonald (1956)
was the last to review the anthracotheres and a new
review of the group is needed.
Suborder TYLOPODA Illerger 1811
Family CAMELIDAE Gray 1821
Subfamily STENOMYLINAE Matthew 1910
Genus PSEUDOLABIS Matthew 1904
PSEUDOLABIS DAKOTENSIS Matthew 1904
Figure 17A-B, D, G; Table 5
Type.-AMNH 9807, female skull missing
basicranium and associated atlas.
Range.-Whitneyan through early late Arikareean
of the Central Great Plains
Referred Specimens.-UNSM 123222, astraga-
lus; UNSM 123227, proximal metatarsals III-IV; UNSM
(field# 6084-92), ungual phalanx, ap = 21.22, articular
surface = 8.75; UNSM (field# 6061-92), ungual pha-
lanx, ap = 20.45, articular surface = 7.79; UNSM (field#
6035-92) cuboid, tr = 25, ap = 35; UNSM (field# 6098-
92) cuneiform; F:AM 141372,juvenile partial skull.
Discussion.-Referral of this material is based on
comparison of the Wagner Quarry material to the large
collection of Pseudolabis housed in the AMNH (e.g.,
juvenile Pseudolabis skull, F:AM 41814 from lower
Arikaree rocks at Muddy Creek, near Lusk, Wyoming)
(see dental measurements in Table 5). There is only one
species of Pseudolabis, P. dakotensis, that ranges from
the Whitneyan to the late Arikareean. The juvenile skull
collected at Wagner Quarry possesses diagnostic char-
acteristics listed by Honey et al. (1998) for the taxon,
such as weak mesostyles on upper molars, relatively
hypsodont teeth, unreduced premolars, a deeply de-
pressed maxillary fossa, and a fully closed orbit. Honey
et al. placed Pseudolabis in an expanded Stenomylinae
because Pseudolabis shares derived characters with
Stenomylus.
Suborder RUMINANTIA Scopoli 1777
Family HYPERTRAGULIDAE Cope 1879
Genus NANOTRAGULUS Lull 1922
NANOTRAGULUS LOOMISI Lull 1922
Figure 15L-M; Table 5
Type.-YPM 10330, almost complete skull and
mandibles.
Type Locality.-Castle Butte, Muddy Creek area,
near Spanish Mines, Wyoming.
Range.-earliest Arikareean to medial Arikareean
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
Figure 17. A-B, F:AM 141372, Pseudolabis dakotensis, partial juvenile skull with P3-M3, Wagner Quarry. A, lateral
view; B, oblique lingual view of dentition, P3-M2, M3 unerupted. C-E, astragalus comparison. C, F:AM 41942,
Pseudolabis dakotensis, adult, lower Arikaree Fm, Little Muddy Creek, Lusk, WY; D, UNSM 123222, Pseudolabis
dakotensis, juvenile, Wagner Quarry; E, F:AM 47863A, Stenomylus hitchcocki, adult, Harrison Fm, Galusha
Stenomylus Quarry, Sioux Co., NE. F-H, metatarsal comparison. F, F:AM 41942, Pseudolabis dakotensis, juve-
nile, lower Arikaree Fm, Little Muddy Creek, Lusk, WY; G, UNSM 123227, Pseudolabis dakotensis, Wagner
Quarry; H, F:AM 47863A, Stenomylus hitchcocki, Harrison Fm, Galusha Stenomylus Quarry, Sioux Co., NE.
Scale bars = 10mm.
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
(Hunt, pers. comm., 2004)
Referred Specimens.-F:AM 141242, R maxilla
with P3-M3, "upper fossil channel" Wagner Quarry sec-
tion; UNSM 48449, L p4-m2, 123296 L dP4; UNSM
123297 lower molar; UNSM 123298, R M2; UNSM
123299, L M2; UNSM 123237, astragalus.
Discussion. Hypertragulus and Nanotragulus
both correspond in size and general morphology to the
small hypertragulid recovered from Wagner Quarry and
the "upper fossil channel". Hypisodus is much smaller,
and the absence ofmesostyles on the upper molars sepa-
rates it from Leptomeryx. Frailey (1979: 157, Table 5)
listed dental characteristics that distinguish
Nanotragulus and Hypertragulus. The P4 in
Nanotragulus has 2 almost equal fossettes, whereas in
Hypertragulus the posterior fossette is smaller than the
anterior fossette. Nanotragulus is more hypsodont than
the brachyodont Hypertragulus. In Nanotragulus the
M3 metastyle is large (larger than the other styles) and
anteriorly slanted. Hypertragulus has a small metastyle
(smaller than the other styles) which is parallel to the
other styles or ribs. Intercolumnar cingula are not usu-
ally present in Nanotragulus; intercolumnar styles are
present. Hypertragulus usually develops long interco-
lumnar cingula. Based on these morphological differ-
ences the dental material from Wagner (Fig. 15L-M)
can clearly be referred to Nanotragulus.
Size is one of the most reliable characters used to
differentiate the various species of Nanotragulus. The
Wagner specimens fall within the size range ofN. loomisi
reported by Frailey (1979:162-165). Frailey demonstrated
that N. intermedius and N. lulli were synonymous with
N. loomisi. This is the common early Arikareean taxon,
and Tedford et al. (2004) use its first appearance to char-
acterize the beginning of the age. The Wagner material
also has more rounded labial cusps in comparison to
younger Nanotragulus species that have V-shaped la-
bial cusps, as reported by Albright (1999).
AGE AND CORRELATION
Previous reports on the Wagner Quarry (Tedford et al.
1985) placed the local fauna in the early Arikareean and
faunal analysis here agrees with this correlation.
Wagner Quarry has all of the same micro-mam-
mal taxa as the Ridgeview If (Bailey, 2004: Table 1) and
is stratigraphically equivalent to it as part of the basal
fluvial Arikaree facies resting unconformably above the
White River Group. Bailey demonstrated that the
Ridgeview If, which is more diverse and numerous in
micro-mammals (35 mammal species), could be corre-
lated with high precision to the "Gering A and B" Ifs of
Swisher (1982). Based on faunal list comparison be-
tween localities, Bailey suggested that the Ridgeview If
was slightly older than the "Gering B" If but younger
than the "Gering A" If= "Brown Siltstone" giving it an
approximate age of 29 Ma (Tedford et al. 2004).
The update by Tedford et al. (2004) of the
Arikareean NALMA characterizes the earliest
Arikareean (Arl) with the first appearance of
Nanotragulus loomisi along with the beavers
Capacikala and Capatanka. Ocajila is also used as
one of the taxa characteristic of the interval. Ocajila is
confined to the earliest Arikareean (Arl) in the central
Great Plains by Tedford et al. (1996). Bailey (2004) rec-
ognized 0. makpiyahe in the Whitneyan Cedar Ridge If
(Setoguchi 1978) from Wyoming, and Korth (1992) de-
scribed an ml from the McCann Canyon If that might
be included in this genus but was larger than 0.
makpiyahe. Whether the range of Ocajila is confined
to the earliest Arikareean is uncertain yet the restriction
of the type species in the Great Plains to the early
Arikareean may still be valid.
Tedford et al. (2004) further listed genera that were
confined to the early early Arikareean such as
Palaeolagus hypsodus and Palaeocastor
nebrascensis. Wagner Quarry If contains Palaeolagus
hypsodus and a castorid that is similar in size and mor-
phology to P nebrascensis. Last occurrences of taxa
in the Great Plains for the early early Arikareean (Arl)
include Agnotocastor, present in the Wagner If, and the
cricetid Eumys. Eumys, a common genus of the
Chadronian, Orellan, and Whitneyan, is only found in
the Arikareean "Brown Siltstone" faunas of the central
Great Plains and is therefore restricted to the earliest
part of the age. Eumys is replaced by the cricetids
Geringia mcgregori and Leidymys in the central Great
Plains (Martin 1974). Tedford et al. (1996) and Bailey
(2004) restrict Geringia mcgregori and Leidymys black
to the early early Arikareean (Arl) in Nebraska. Both
taxa are reported from "Brown Siltstone" localities (Mar-
tin 1974; Swisher 1982), the Blue Ash If (Martin 1974),
and the Gering Formation (Martin 1973; Swisher 1982).
Geringia mcgregori is also reported from the northern
plains Kealey Springs If in the late early Arikareean
(Ar2).
One of the aplodontids in the Wagner If,
Downsimus chadwicki, is reported from UNSM local-
ity Mo- 108 in the Gering Formation of the Wildcat Ridge
and from the Ridgeview If, but not from the "Brown
Siltstone" or any other localities stratigraphically above
the Gering Formation or its equivalents (Bailey 2004).
Elsewhere, Downsimus was named for material from
the Sharps Formation (Macdonald 1970), and Storer's
(2002) faunal identifications of the Kealey Springs If
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
Gering Fm
Wildcat Ridge
Roundhouse Rock pisolitic
ash 40Ar/39Ar
28.11 + 0.16
Chimney Rock perrierite
ash 40Ar/39Ar
-'28.26 + 0.05
Twin Sisters Pumice
'Conglomerate 40Ar/39Ar
28.31+0.03
Wagner Q. Section
"The Brown Siltstone" -Wildcat
Ridge
NP3 30.05+0.19
NP2
NP1
Figure 18. Correlation of the Wagner Quarry section to the Global Polarity Time Scale. (Berggren et al., 1995)
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
LO CO ..0.CZ
O) x Q) 0 Zi
M Q. ( O (D. -
z im ,, I 1 I 1o
0) o .2 .0ccuV 0 : CO (
(1) 0) C CM C
Zo c |Nebraska I) I m to 00 II I I
E: ) C13
Pine Wildcat k3 CS.Z L a a .
Ridge Ridge Dakot 6-k 0
Ankare
C8r
27
28
C9r
(1)
(D
* .lr
29
ClOr
ir
30
11r
Monroe
Creek
< "basal
Arikaree"
Wagner
Quarry
CL. (D
) ++NP i
"Monroe
Creek"
----7-
Upper
Sharps
Lower
Sharps
Arikaree
undiv.
Gering Fm
*1I.
+NP3+
+NP2+
-NP+P
Poleside
Mbr
++UW++
Whitney
Mbr
I
Figure 19. Composite chronostratigraphic chart of selected taxa in Nebraska and South Dakota. (modified from
Tedford et al., 1996). "Brown Siltstone in Pine Ridge is correlated using Toadstool Section (Tedford et al., 1996: Fig.
7:324). Gering Fm dated ashes in Fig. 18.
Whitney
Mbr
extended the range of Downsimus in the northern Great
Plains into the late early Arikareean. The other aplodontid,
Alwoodia, is listed by Tedford et al. (2004) as having its
first appearance in the Great Plains during the late early
Arikareean. The recognition of this taxon in the Wagner
Quarry If extends the range down into the early early
Arikareean (Arl) for the Great Plains, which would agree
with the genus' first appearance in the John Day region
at -~ 28.7 Ma.
Some of the larger taxa in Wagner If are not as
restrictive in age determination in comparison to the small
mammals, but they do provide support for assignment to
the early Arikareean. Paradaphoenus tooheyi (Hunt
2001) is transitional between the Orellan P minimus and
the late early to "medial" Arikareean P cuspigerus.
Nimravus has its last appearance in the late early
Arikareean (Tedford et al. 2004). The oreodonts belong
to genera that are common to other early Arikareean
localities in the Great Plains. Pseudolabis is a common
camel in the Whitneyan and early Arikareean (McKenna
1966) and is the beginning of the stenomyline radiation
of camels that became dominant in the later Arikareean
of the Great Plains (Honey et al. 1998).
Based on the definition and characterization of the
early early Arikareean (Arl) as reported by Tedford et
al. (2004), the presence of Nanotragulus loomisi,
Agnotocastor, Geringia mcgregori, Leidymys black,
and Palaeolagus hypsodus firmly places the Wagner
Quarry If in this time period. None of the defining or
first appearance taxa (except Alwoodia) of the late early
Arikareean (Ar2) such as Amphechinus, Parvericius,
Gripholagomys, Archaeolagus, Promylagaulus,
Gregorymys, and Stenomylus are present in the Wagner
fauna.
Based on this study, which adds to the work of
Tedford et al. (1996) and Bailey (2004), the early early
Arikareean (Arl) can be resolved into three phases: the
first phase of the early Arikareean is represented by the
faunas of, or equivalent to, the "Brown Siltstone" or lower
Sharps (Blue Ash If, Martin 1974; Simpson 1985; Gering
A, Swisher 1982; lower Cabbage Patch faunas,
Rasmussen 1977). This is followed by the next phase
exemplified by the Pine Ridge basal Arikaree faunas
from Wagner If and Ridgeview If, and possibly the Gering
B If of Swisher (1982). The upper Gering Formation(as
defined by Swinehart et al. 1985) faunas and their equiva-
lents in the upper Sharps represent a third phase. These
phases exhibit a step-wise transition of change between
White River taxa and taxa of the early Arikareean as
suggested by Bailey (2004:104). The earliest phase fau-
nas retain c. 25% White River taxa. The faunas equiva-
lent to Wagner include only about 10% relict taxa; and
BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1)
in the third phase there are practically no White River
taxa.
Some further discussion regarding the Kealey
Springs If is warranted here given the above problems
with range extensions (e.g. Downsimus, Geringia, and
also Nanodelphys) outside of the central Great Plains.
The Kealey Springs If was correlated to the late early
Arikareean (Ar2) and it is believed to be equivalent to
the "Monroe Creek" sediments in Nebraska (Storer 2002;
Tedford et al. 2004). Some of these problems may be
due to the fact that the Monroe Creek Formation of the
Pine Ridge and its equivalents in Nebraska have pro-
duced little in the way of comparative fossils (Bailey
[2004] uses the South Dakota Wewela If [Skinner et al.
1968] to represent this interval). However, the "Monroe
Creek" sediments of the Wildcat Ridge have yielded
several micro-mammal ant hill collections that have never
been studied. The study of the Cedromus and Alwoodia
material of this report indicates that some of the early
Arikareean taxa could extend upward into the late early
Arikareean and may more closely match the Kealey
Springs If than previously thought. Preliminary study here
indicates that the faunas contain mylagaulid rodents simi-
lar to the Kealey Springs If as well as cricetid rodents.
These "Monroe Creek Ant Hill" faunas should be fur-
ther investigated to help refine the characterization of
the late early Arikareean in the central Great Plains.
The basal Arikaree sediments and the overlying
Monroe Creek Formation in the Pine Ridge do not have
any radioisotopic dates at present. As mentioned previ-
ously the Wagner Quarry section is in proximity to an
outcrop of the Nonpareil Ash. This ash has been mag-
netically correlated to the NP3 ash of the Wildcat Ridge
(Tedford et al. 1996) which has been dated from out-
crops there (Swisher & Prothero 1990). At the Wildcat
Ridge, the Gering Formation and "Brown Siltstone" are
constrained in age by several radioisotopic dates (Tedford
et al. 1996). The oldest of these ages is represented by
the NP3 ash (30.05 +/- 0.19 Ma) in the upper part of the
"Brown Siltstone". The youngest dated ash in the Gering
Formation (Roundhouse Rock pisolitic ash) establishes
an upper boundary at 28.11+/- 0.18 Ma. Two other ashes
within the Gering further constrain the age of this for-
mation: the Twin Sisters Pumice Conglomerate (28.31
+/- 0.03 Ma) near the base and the Chimney Rock
perrierite ash (28.26+/- 0.05 Ma).
Work in the Wildcat Ridge by D. Prothero (Tedford
et al. 1996) has shown that fluvial basal Arikaree depos-
its of the pumice-bearing Gering Formation are reversely
polarized at their base and do not change into normal
polarity until the uppermost part of the formation. Using
the above geochronology, Prothero correlated the Gering
HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska
Formation to the lower part of Chron 9 and the upper
part of the "Brown Siltstone" to Chron 11 n and part of
Chron lOr paleomagneticc time scale of Berggren et al.
1995). "The Nebraska sections show a hiatus in Chron
C 1 Or with Chron C 1 On missing" (Tedford et al. 1996:317).
The paleomagnetic results of the Wagner Quarry
section show that most of the section is normally polar-
ized, unlike the top of the "Brown Siltstone" or the ma-
jority of the Gering Formation. A single section of nor-
mal polarity in the Pine Ridge is not strong evidence that
the basal Arikaree deposition there is entirely different
from the Gering Formation. However, this normal sig-
nature is supported by the same polarity signature of the
lithologically similar basal fluvial sediments exposed at
the bottom of the Monroe Creek Canyon section (the
type section for Hatcher's [1902] Monroe Creek beds
and Harrison beds) located to the east of Wagner Quarry
north of Harrison, Nebraska (Hayes 2004). MacFadden
& Hunt (1998) correlated the base of their composite
Arikaree section to Chron C9r (Berggren et al. 1995),
similar to the Gering Formation, because they suggested
that the fluvial sediments at the foot of the Pants Butte
section represented the same interval as the Gering For-
mation in the Wildcat Ridge. In Monroe Creek Canyon
there are considerable (~- 40m) Arikaree fluvial sedi-
ments, referred to above, that are not represented in the
Pants Butte section and occur stratigraphically below
the cross-bedded sandstones at the bottom of the Pants
Butte section.
Faunal comparison with the Ridgeview If and
Gering faunas in Nebraska places the Wagner Quarry If
firmly in the early Arikareean (Arl) or between 30-28
Ma. Detailed comparison with the faunas of this inter-
val and stratigraphic correlation with the Ridgeview If
suggests an older age than the upper Gering faunas.
The Wagner Quarry section is constrained in its lower
placement by the Nonpariel Ash 3 date. These param-
eters leave one normal chron of appropriate age that
would fit the polarity signature of the Wagner Quarry
Section- Chron lOn (Berggren et al. 1995). This cor-
relation is also supported by the small reversal within
Cl On- C On. 1 r, which is probably represented in the
short reversal of the Wagner section (see Fig. 18). The
basal Arikaree of the Pine Ridge therefore helps to fill
the gap in time that may not be recorded by sediments in
the Wildcat Ridge and extend the range of several taxa
into this interval.
SUMMARY AND CONCLUSIONS
The Wagner Quarry fauna is the first large mammal
concentration described from the historically important
Pine Ridge basal Arikaree Group and the first paleo-
magnetic study of the basal Arikaree in the Pine Ridge.
These two studies provide a more accurate correlation
than was previously possible of the basal Pine Ridge
Arikaree Group to the basal Arikareean sediments in
the Wildcat Ridge, as well as to early Arikareean sedi-
ments and faunas outside of Nebraska. The indepen-
dent paleomagnetic correlation shows that the initial basal
fluvial deposition of the Pine Ridge Arikaree paleovalley
was not synchronous with the Gering Formation, Arikaree
Group, deposition in the Wildcat Ridge.
The Wagner Quarry section represents a stack of
fluvial sediments, from main channel fills (Wagner
Quarry, the "upper fossil channel" and the "top chan-
nel"), through distal channel point bar deposits (uniform
ripple layers), to flood plain or over-bank deposits that
are separated by diastems when pedogenic alteration
took place. The fossils of Wagner Quarry represent a
relatively wet riparian environment that became increas-
ingly drier by the time the "upper fossil channel" was
deposited. Channel sediments become increasingly bet-
ter sorted and mineralogically similar towards the top of
the section as indicated by less influx of allocthonous
lithic material in the Wagner Quarry channel and re-
working of completely intraformational sediments in the
"top channel".
Comparison of the Wagner Quarry If to the faunas
of the Gering Formation, the "Brown Siltstone", the
Ridgeview If, and the faunas of the Sharps in South
Dakota as well as to Tedford et al.'s (2004) defining and
characterizing taxa of the early early Arikareean, place
the Wagner If biochronologically in this interval (Arl),
or approximately 30-28 Ma.
The Wagner Quarry section is predominantly mag-
netically normal. This is different from the Gering For-
mation in the Wildcat Ridge, which is mostly magneti-
cally reversed and the "Brown Siltstone," which is also
reversed in its upper section. Faunal correlation places
the Wagner Quarry in the early early Arikareean
NALMA, slightly older than the radioisotopically cali-
brated Gering Formation faunas and slightly younger than
the "Brown Siltstone" Ifs. This constrains the
magnetostratigraphy to Chron O1n (28.25-28.87 Ma,
Berggren et al. 1995). The section records the short
reversal of C1 On. 1 r.
Correlation using the Wagner If and the Wagner
Quarry magnetostratigraphy shows that there is a three
phase transition within the early early Arikareean. The
first phase is characterized by the local faunas of the
"Brown Siltstone"; the second phase by the Wagner If
and the Ridgeview If; and the third by the Gering fau-
nas. Characteristic White River taxa become increas-
ingly rarer in each phase.
The recognition of a new species of Cedromus in
the Wagner If and the assignment of the Gering Forma-
tion "Miospermophilus" (Martin 1973) to Oligo-
spermophilus extends the range of the Cedromurinae
into the early Arikareean. Alwoodia is also recognized
for the first time in the early early Arikareean (Arl) of
the central Great Plains.
ACKNOWLEDGEMENTS
This study was produced as part of the author's disser-
tation research and was supported by funding from the
University of Nebraska State Museum and the Depart-
ment of Geosciences. My deepest appreciation is ex-
tended to my advisor, Robert M. Hunt, Jr., who sug-
gested this study and answered years of questions and
made numerous suggestions for improvement. I thank
Mike Voorhies, David Loope, and Patricia Freeman, for
their review of the manuscript in dissertation form. Ac-
cess to the American Museum of Natural History col-
lections was granted by Richard Tedford who also pro-
vided valuable discourse on the taxa and problems of
the Arikareean. My thanks are owed to those who col-
lected and prepared the Wagner Quarry fossils over 30
years including: Richard Tedford, Ted Galusha, Loren
Toohey, Robert Hunt, Jr., Robert Skolnick, Xiao-feng
Chen, Jim Swinehart, Carl Swisher, and Ellen Stepleton.
For help in collecting paleomagnetic samples my thanks
go to Efthimia Papastavros and Abaco Richardson.
Bruce Bailey deserves special appreciation for many
hours of productive discussion and providing unlimited
access to the specimens of the Ridgeview If (collected
through funding by the Nebraska Department of Roads).
Josep Par6s and the staff of the University of Michigan
geomagnetic laboratory deserve great recognition and
thanks for allowing the use of their facilities and for giv-
ing valuable education on the processes of
paleomagnetics. My appreciation also goes to two anony-
mous reviewers who greatly improved this manuscript
for publication. Continued access to Wagner Quarry was
generously granted by Walter Montague, Chadron, Ne-
braska.
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