FIELDTANA
Geology
NEW SERIES, NO. 52
A Paleopopulation of Coryphodon lobatus
(Mammalia: Pantodonta) from Deardorff Hill
Coryphodon Quarry, Piceance Creek Basin, Colorado
Elizabeth M. McGee
William D. Turnbull
January 8, 2010
Publication 1554
PUBLISHED BY FIELD MUSEUM OF NATURAL HISTORY
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Cover photograph: Ventral view of skull, young adult Coryphodon lobatus (PM39385) from Deardroff Hill Coryphodon Quarry,
Piceance Creek Basin, Colorado. Photograph by John Weinstein, @ 2009 The Field Museum, Image# GE086493_13d.
PUBLISHED BY FIELD MUSEUM OF NATURAL HISTORY
Geology
NEW SERIES, NO. 52
A Paleopopulation of Coryphodon lobatus
(Mammalia: Pantodonta) from Deardorff Hill
Coryphodon Quarry, Piceance Creek Basin, Colorado
Elizabeth M. McGee
Department of Biological Sciences
San Jose State University
San Jose, CA 95192-0100, USA.
email: emcgee@email. sjsu. edit
William D. Turnbull
Department of Geology
Field Museum
1400 South Lake Shore Drive
Chicago, 1L 60605-2496, U.S.A.
Accepted September 25, 2009
January 8, 2010
Publication 1554
PUBLISHED BY FIELD MUSEUM OF NATURAL HISTORY
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Table of Contents
Abstract . 1
Introduction . 1
Abbreviations and Institutions . 1
Dental Terminology and Measurements . 1
Geologic Setting and History of Discovery . 1
Composition and Condition of the Deardorff Hill Coryphodon Quarry Assemblage . 2
Systematic Paleontology . 4
Coryphodon lobatus . 4
Age Determination . 5
Age Class 1 (young subadult) . 6
Age Class 2 (subadult) . 7
Age Class 3 (young adult) . 7
Age Class 4 (adult) . . 7
Age Class 5 (advanced/old adult) . 8
Aspects of Cor yphodon Life History . 8
Sociality in Coryphodon and Future Directions . 8
Acknowledgments . 9
Literature Cited . 9
List of Illustrations
1. Dental terminology . 2
2. Map of Piceance Creek Basin . 2
3. Relative representation of postcranial elements . 3
4. Metric variation in lower first molar . 4
5. Dental eruption sequence for C. lobatus . 5
6. (A) Coryphodon lobatus, PM 39436. (B) C. lobatus, PM 39381 . 6
7. (A) Coryphodon lobatus PM 39605/39665. (B) C. lobatus, PM 39702 . 6
8. (A) Coryphodon lobatus PM 39385. (B) C. lobatus, PM 35873 . 7
9. (A) Coryphodon lobatus PM 35870. (B) C. lobatus, PM 35865 . 7
10. Metric variation in the lower third molar of Coryphodon lobatus from Deardorff Hill Coryphodon Quarry . 8
List of Tables
1. Inventory of postcranial elements . 3
2. Summary statistics of molar measurements . 5
Appendices
I. Metric measurements of lower adult dentition of Coryphodon lobatus from Deardorff Hill Coryphodon Quarry . 10
11. Metric measurements of upper adult dentition of Coryphodon lobatus from Deardorff Hill Coryphodon Quarry . 11
III. Metric measurements of juvenile dentition of Coryphodon lobatus from Deardorff Hill Coryphodon Quarry . 12
iii
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https://archive.org/details/paleopopulationo52chic
A Paleopopulation of Coryphodon lobatus (Mammalia: Pantodonta) from
Deardorff Hill Coryphodon Quarry, Piceance Creek Basin, Colorado
Elizabeth M. McGee and William D. Turnbull
Abstract
A unique early middle Wasatchian paucispecific bone bed from Deardorff Hill in the Piceance Creek Basin of
Colorado contains a minimum of 12 individuals of Coryphodon lobatus that range in age from subadult “yearlings” to
senescent individuals. The preponderance of Coryphodon material in this assemblage (92% of the 700+ complete bones
represent a single species of Coryphodon) argues for a “catastrophic” origin for this assemblage. The Deardorff Hill
Coryphodon Quarry preserves one of the most complete dental eruption sequences reported to date for Coryphodon and
allows interpretation of demographic and life history attributes not ordinarily observable, such as evidence of seasonality
in births. In addition, females are disproportionate in number to males, further confirming that this species had a
polygynous social structure. Mass mortality assemblages are useful in eliciting a better understanding of the range of
variation in single populations. Metrically, the molars of C. lobatus specimens from Deardorff Hill Coryphodon Quarry
have coefficients of variation ranging from 4 to 11, which are comparable to metric variation observed in other mass
death Coryphodon assemblages. An understanding of the range of variation in this highly variable taxon is of particular
importance in the taxonomy and phylogenetic relationships of this ubiquitous Eocene mammal.
Introduction
Coryphodon was a large-bodied, subdigitigrade browsing
mammal common in North America, Europe, and Asia from
the latest Paleocene to the early Eocene. In addition to the
ubiquitous occurrence of isolated teeth and partial jaws in
fossil outcrops, there are several instances of mass death
assemblages of Coryphodon , such as Roehler’s Coryphodon
Catastrophe Quarry (RCCQ) in Wyoming (McGee, 2001,
2002) and AMNH Quarry 242 in New Mexico (Lucas, 1984).
Here we report an additional early middle Wasatchian
paucispecific assemblage from Deardorff Hill in the Piceance
Creek Basin of Colorado. Originally excavated in the 1940s
by Bryan Patterson and colleagues, this assemblage provides
tantalizing details on intraspecific and interspecific variation
in Coryphodon. Below we describe the geologic and tapho-
nomic setting of Deardorff Hill Coryphodon Quarry and
provide a detailed description of the dental material of
Coryphodon lobatus, including a reconstruction of the
eruption sequence of the dentition. As a “death assemblage,”
Deardorff Hill Coryphodon Quarry provides an unusual
opportunity to assess paleobiological and paleodemographic
attributes of a population not normally preserved in the fossil
record.
Abbreviations and Institutions
amnh = American Museum of Natural History, New York,
NY; rccq = Roehler’s Coryphodon Catastrophe Quarry, WY;
ucmp = University of California Museum of Paleontology,
Berkeley, CA; fmnh or fm = Field Museum, Chicago, IL; pm
or p = Field Museum fossil mammal collection.
Dental Terminology and Measurements
L = length; AW = anterior width; PW = posterior width;
MNI = minimum number of individuals; N = number of
specimens; CV = coefficient of variation; SD = standard
deviation. All measurements are in millimeters. Cusp and loph
designations for the M3 and M~’ are illustrated in Figure 1.
Length and width of individual teeth were measured along
maximum dimensions in anteroposterior and transverse
planes, respectively. Measurements were taken using Fowler
Ultra-Cal II electronic calipers.
Geologic Setting and History of Discovery
Deardorff Hill Coryphodon Quarry is situated on the east side
the Piceance Creek Basin in northwestern Colorado. The eastern
margin of the Piceance Creek Basin, which formed during the
Late Cretaceous, is framed by the Axial Basin arch. White River
uplift, and Elk Mountains, while the western margin comprises
the Uncompahgre uplift, Douglas Creek arch, and the Uinta
arch and was formed during the Late Paleocene and Early
Eocene (Figure 2; Kihm, 1984). The three early Tertiary rock
units include the Debeque (originally identified as Wasatch by
Hayden, 1873), Green River, and the Uinta Formations.
In the 1930s and early 1940s, Bryan “Pat” Patterson of the
Field Museum led collecting expeditions to the Plateau Valley
region in the Piceance Creek Basin (western Colorado). In
1941, crew member John M. Schmidt discovered Deardorff
Hill Coryphodon Quarry (“42-41”), which was subsequently
excavated by Schmidt and the chief fossil preparator for the
Field Museum, James H. Quinn. While Patterson’s work in
western Colorado culminated in a number of publications on
FIELDIANA: GEOLOGY, N.S., NO. 52, JANUARY 8, 2010, PP. 1-12
anterior cingulid
protoconid
metalophid
cristid obliqua
hypoconid
hypolophid
posterior cingulid
parastyle
anterior cingula'
protoloph
preparacrista
paracone
postparacrista
-mesostyle
■premetacrista
-postmetacrista
metacone
postprotocrista
protocone
Fig. 1. Terminology of the cusps and lophs of the upper and
lower molars of Coryphodon lobatus as illustrated by a left M3 and a
right M3. The terminology used in describing Coryphodon lower
dentition follows Lucas (1984). Lucas’s (1984) terminology is derived
from Szalay (1969) and Simpson (1929) with the exception that the
cusp identified by Simpson (1929, fig. 8 A') as the entoconid is most
likely the hypoconulid (Uhen and Gingerich, 1995). This is a
significant point since the presence or absence of the entoconid is
an important nonmetric trait in distinguishing species of Coryphodon.
After Lucas (1984, figs. 50F and 5 IF).
Titanoides and other Tertiary mammals, his work on
Coryphodon was restricted to a single paper (Patterson,
1939) published prior to the discovery of the Deardorff Hill
Coryphodon Quarry.
Kihrn (1984) described the “Plateau Local Fauna” as a
series of Middle Clarkforkian (Earliest Eocene) through late
Wasatchian (late Early Eocene) faunas. He identified three
Tertiary mammal locality sequences in the Piceance Creek
Basin: 1) White River in the northern end of the basin and in
the Gray Hills region, 2) farther south, the Roan Cliff region
(northwest of Battlement Mesa), and 3) the Mamm Creek
region (northeast of Battlement Mesa). Deardorff Hill
Coryphodon Quarry is located in the southeastern margin of
the Mamm Creek region. This region, which extends
northward to the Grand Hogback mountains and southward
to the northeast corner of Battlement Mesa, contains
predominantly Clarkforkian to Wasatchian exposures.
Composition and Condition of the Deardorff Hill
Coryphodon Quarry Assemblage
The Deardorff Hill Coryphodon Quarry is a paucispecific
assemblage consisting of over 700 recognizable skeletal
elements (not including ribs) and over 600 fragments of C.
Fig. 2. Piceance Creek Basin in northwestern Colorado. The
extent of the basin is demarcated in light gray. Tertiary mammal
locality sequences worked by Kihm (1984) in the Piceance Creek
Basin are shown in darker gray and include White River in the
northern end of the basin and in the Gray Hills region, the Roan Cliff
region (north of Battlement Mesa), and the Mamm Creek region (east
of Battlement Mesa). Deardorff Hill Coryphodon Quarry is located in
the southeastern margin of the Mamm Creek region.
lobatus. The MNI based on mandibular and maxillary
elements is 10, while MNI based on the right humerus is 12.
Information loss is clearly evident in the inventory of bones
from this quarry, as depicted in Figure 3 and Table 1, which
show the relative abundance of different postcranial elements
in the assemblage based on an MNI of 12. The assemblage is
biased against smaller elements (e.g., clavicle, sternum, and
bones that make up the manus and pes) that, according to the
classic taphonomy studies of Voorhies (1969), are the first to
be removed by water currents on deposition. Voorhies (1969)
suggests that shape of an element influences its potential for
transport, so flat bones that float more easily, such as the
scapula and innominate, should likewise be absent in an
assemblage dominated by larger, heavier bones (i.e., humerus,
femur). The profile in Figure 3, however, shows that
innominates and scapulae are only slightly less common than
larger bones such as the femur. The humerus, the stoutest
bone in the Coryphodon skeleton, is noticeably more common
than any other single element. These biases would suggest that
the assemblage was only briefly worked by water currents
before deposition and burial.
Fragmentation and compression are characteristic postmor¬
tem alterations in the material from Deardorff Hill Corypho¬
don Quarry. Few of the elements were preserved articulated in
situ (e.g., PM 39705: atlas through 5th cervical vertebrae; PM
39392: articulated pelvic girdle with left and right innominates,
sacrum, and several caudal vertebrae) despite careful prepa¬
ration of the blocks in the lab at the Field Museum.
2
FIELDIANA: GEOLOGY
1
Fig. 3. Relative representation of postcranial elements of Coryphodon lobatus from Deardorff Hill Coryphodon Quarry. Percentages are
based on an MN1 of 12.
Hill (1979) suggested that the taphonomic profile of an
assemblage may reflect the sequence of disarticulation (Hill,
1979). Water, long known to play an important role in the
dispersal of bones (Voorhies, 1969; Behrensmeyer, 1975,
1991), also is a factor in determining the disarticulation
sequence of a carcass. In humid conditions, for example, a
bovid will disarticulate from the extremities inward, whereas
in drier conditions, disarticulation proceeds outward from the
body to the extremities. If an assemblage is affected by the
sequences of bone disarticulation, a bias against proximal or
distal bones would be predicted. Counts of distal (i.e., radius,
ulna, tibia, and fibula) and proximal (i.e., humerus, scapula,
innominate, and femur) elements in the Deardorff Hill
Coryphodon Quarry were analyzed using the Mann-Whitney
test for independence of means. There is no significant
difference between the number of proximal vs. distal elements
in this assemblage (p — 0.686). The assemblage was also
analyzed to determine if there were differences between left
and right elements of the limb. Similarly, there was no
statistically significant difference between left and right (p =
0.931).
Information on relative representation of different elements,
the assessment of proximal vs. distal, and left vs. right
elements, plus visual inspection of the physical characteristics
of the bones, all suggest that burial was rapid and that
reworking was minimal.
More than 97% of the assemblage is monospecific.
Additional mammals present include primates ( Cantius
abditus : P26477, P26656, P26660), rodents ( Paramys coper.
P26659), creodonts ( Oxyaena forcipata: P26647), carnivores
( Didymictis protenus : P26649), condylarths ( Phenacodus pri-
maevus: PI 5697; Hyopsodus sp. nr. H. latidens : P26650,
P26697; Meniscotherium tapiacitis : P26658), and perissodac-
tyls ( Hyracotherium sp. C. sensu Kihm 1984: PI 5705, P26516,
P26566, P26567, P26646, P26651, P26655, P26657, P26661,
P26664, P26665). The assemblage also contains a few
Table 1. Inventory of postcranial
abundance estimates.
elements of C. lobatus
from Deardorff Hill
Coryphodon Quarry, and
associated relative
Number in assemblage
Number per individual
Number expected in
assemblage if MNI = 12
Relative abundance
Humerus (L = 11; R — 12)
23
2
24
0.96
Radius (L = 2; R = 3; indet. = 9)
14
2
24
0.58
Scapula (L = 6; R = 4; indet. = 1)
11
2
24
0.46
Ulna (L = 6; R = 7)
13
2
24
0.54
Femur (L = 6; R = 8)
14
2
24
0.58
Innominate (L = 6; R = 4; indet = 1)
11
2
24
0.46
Tibia (L = 7; R = 5)
12
2
24
0.50
Fibula (L = 0; R = 2; indet = 3)
5
2
24
0.21
Ribs
259
34
408
0.63
Vertebrae
207
47
564
0.37
Patella (L = 1; R = 3; indet. = 3)
7
2
24
0.29
Manus+pes
225
106
1272
0.18
Clavicle (indet. = 3)
3
2
24
0.13
Sternum
2
6
72
0.03
MCGEE AND TURNBULL: CORYPHODON LOBATUS FROM DEARDORFF HILL CORYPHODON QUARRY 3
■ Deardorff Hill Coryphodon Quarry
□
□ Coryphodon lobatus
□
n
□
□
□
□
□
■
■
□ □
ft
□
□
□ □
□
□
□
□
■ ■
■ □
□
■:
ft
□
□
■
□ ■
22 24 26 28 30 32 34 36
M, length (mm)
Fig. 4. Metric variation in the lower First molar of Coryphodon
from Deardorff Hill Coryphodon Quarry compared with lower First
molar of Coryphodon lobatus reported by Lucas (1984). The Deardoff
Quarry specimens slightly extend the size range of C. lobatus.
specimens of turtles (Chelonia: Trionychidae?). The prepon¬
derance of Coryphodon material in this assemblage (700+
complete bones) and the relative absence of material from
other species (21 specimens total, representing eight species of
mammals, plus a small assortment of turtle scrap) argues
strongly for a “catastrophic” origin for this assemblage.
A catastrophic or mass death accumulation is also charac¬
terized by the predominance of a single taxon which shows an
age proFile that is representative of a living population (Kurten,
1953; Voorhies, 1969; Turnbull & Martill, 1988). In contrast,
assemblages formed over an extended period of time have an
age profile that reflects greater mortality in juveniles and old
adults (Klein & Cruz-Uribe, 1984; Haynes, 1985, 1987). The
Deardorff Hill Coryphodon Quarry has an age profile in which
each age-group (see below) is represented by about the same
number of individuals and is therefore more comparable to a
mass death accumulation.
Systematic Paleontology
Class Mammalia Linnaeus, 1758
Order Pantodonta (Cope, 1873)
Family Coryphodontidae (Marsh, 1876)
Coryphodon lobatus (Cope, 1877)
(Figures 1, 5-8)
Referred Specimens — PI 5628; mandible with L^-M^,
Rli-M, and skull with LI1”3, LC, LP2-M3, RI13, RC, RP2-
M3; PM 35865: mandible with LI^2, LP,-M3, RI2-I3, RPj-
M3 and associated lower L/C and LI3; PM 35870: dentary with
LP]-M2, associated lower LC and two incisors, and skull with
LC, LP2'4, LM1 3, RP2^4, RM1 3; PM 35871: skull with LI1-
M3, RI2-C, RP2-M3; PM 35873: mandible with LI,-M3, RI)-
C, RP2-M3; PM 35878: mandible with LIj-M3, RI)-I2, RC-
M3; PM 35879: maxillary fragment with LdP2 4, LM1; PM
35903: skull with LP2-M3 andlRP2-M3; PM 39374: mandible
with LI !_2, LP2-M3, RI i_2, RP]-M3; PM 39375: mandible
with LdPj_3, LM) and RMp PM 39381: maxillary fragment
with RdP'^-M1 (possibly the other half of PM 39686); PM
39385: skull with LC-M3 and RC, RP2-M3; PM 39436:
mandible with LdP2_4-M] (possibly part of PM 35879); PM
39605/39665: skull with LI3?, LdP4, LM1”2 and RdP4, RM1”2;
PM 39673: skull with LI3, LC, LP2-M3 and RI3, RC, RP2-M3;
PM 39686: maxillary fragment with LdP1 4-M'; PM 39702:
mandible with LdPt, LdP3_4-M2 and RI3?, RdP,^-M2.
Description — Coryphodon species have historically been
difficult to distinguish (Earle, 1892; Patterson, 1939) because
of individual, sexual, and interspecific variation. Lucas’s
(1984) treatment remains the most comprehensive to date
and provides a basis for identifying the species present at
Deardorff Quarry. Lucas (1984) argues that the following
characteristics of the M~’ are useful in identifying species of
Coryphodon (Figure 1): 1) presence and size of M3 metastyle,
2) relative length and orientation of the postparacrista-
premetacrista crest, 3) presence or absence of postprotocrista,
and 4) size of the postero-lingual cingulum. For the M3, the
following characteristics are distinctive (Lucas, 1984): 1)
length and orientation of the hypolophid, 2) size of the
posterior cingulid, 3) presence or absence of the entoconid,
entocristid, and other postero-lingual cuspulids and their
position and relative size, and 4) size and orientation of the
cristid obliqua.
We assign the Deardorff Quarry Coryphodon specimens to
C. lobatus. The M3 of these specimens possess 1) a
semitransverse hypolophid (although not quite as parallel as
in C. subquadratus), 2) a small but distinct entoconid (absent
in C. molestus; C. anthracoideus has numerous lingual cusps),
and 3) a well-developed posterior cingulum with an incipient
cusp on the lingual side. The hypoconulid in the Deardorff
specimens is more lingual (as in other species) than in C.
proterus in which the hypoconulid is very centrally placed. The
M3 of the specimens from Deardorff Hill Coryphodon Quarry
1) typically lack an M3 metastyle (or otherwise have a very
small one), 2) have a distinctive ectoloph because of the
orientation of the postparacrista-premetacrista crest, and 3)
have a well-developed postprotocrista. Although several of the
Coryphodon from Deardorff Hill Coryphodon Quarry possess
a postero-lingual cingulum, Lucas (1984) argues this is not a
feature of C. lobatus. A large postero-lingual cingulum is seen
in C proterus. The Deardorff Hill Coryphodon Quarry
specimens cannot be C. proterus, however, because of the
angle formed by the postparacrista-premetacrista; in C.
proterus, the postparacrista-premetacrista is straight and
nearly transverse (Lucas, 1984).
Lucas (1984) assigns Deardorff Hill Coryphodon Quarry
specimens to two Coryphodon species, C. lobatus (PI 5628, PM
35865, PM 35873) and C. molestus (PM 35870, PM 35871, PM
35903, and PM 35878). We observe most, if not all, of the
characteristics noted above for C. lobatus on the specimens
Lucas (1984) designates to C. molestus. For PM 35870, the
upper third molars lack a metastyle, the postprotocrista is
present, and there is a distinctive ectoloph. Both PM 35871
and PM 35903 have a very small metastyle on M ; a
postprotocrista is present, and the ectoloph is distinctive.
PM 35878 has a very small entoconid on the M3; the
hypolophid is nearly transverse, and the posterior cingulid is
present and well developed. Metrically, PM 35870, PM 35871,
PM 35903, and PM 35878 (see below) are smaller than the
other Deardorff Hill Coryphodon Quarry specimens noted by
4
FIELDIANA: GEOLOGY
Table 2. Summary statistics of molar measurements for C.
lobatus from Deardorff Hill Coryphodon Quarry. All measurements
in mm.
N
Mean (mm)
SD
Range (mm)
CV
Lower dentition
p4l
6
23.11
1.58
20.71-24.80
6.84
P4W
6
19.40
1.14
17.97-20.58
5.87
M,L
9
27.73
2.70
25.08-32.57
9.75
M,AW
9
20.45
1.18
18.31-22.66
5.77
M,PW
9
20.68
0.88
19.54-22.32
4.27
M2L
6
34.84
3.46
30.17-39.47
9.94
MAW
7
25.83
1.59
24.20-28.64
6.16
IVLPW
6
24.87
1.60
22.97-27.18
6.45
MfL
4
38.91
4.46
35.29-44.83
11.45
MAW
5
28.01
1.80
26.24-30.15
6.42
MfiPW
4
25.25
1.39
23.63-26.94
5.50
Upper dentition
P4L
6
20.15
1.70
18.16-22.58
8.41
P4W
6
32.00
1.36
30.64-34.34
4.26
M'L
10
27.92
3.03
22.81-31.71
10.84
m’aw
10
31.03
1.61
28.77-34.83
5.18
m'pw
9
30.14
2.69
26.37-36.15
8.93
m2l
7
33.52
2.68
30.28-36.92
7.99
m2aw
7
38.40
1.28
37.28-40.54
3.34
m2pw
7
37.43
1.70
35.78-40.23
4.53
m3l
6
32.74
3.44
28.40-38.40
10.51
m3w
6
44.16
3.76
40.14-49.55
8.51
Lucas (1984), but we argue that these specimens should be
classified with C. lobatus.
Coryphodon species have also traditionally been differenti¬
ated metrically. An important caveat, however, is that
interspecific variation of taxonomic consequence is best
assessed using metric measurements on elements that are not
sexually dimorphic. Gingerich (1981) suggests that the central
cheek teeth (P4, Mj, and M2) are unimodally distributed
within a species; of the three, the first molar shows the least
variation within mammalian species (Gingerich, 1974). A
bivariate plot depicting the relationship between length vs.
width of the lower first molar for the Deardorff Hill
Coryphodon Quarry specimens and other C. lobatus is
presented in Figure 4. The Deardorff Hill Coryphodon
Quarry assemblage moderately extends the size range for
C. lobatus with the individuals from Deardorff Hill
Coryphodon Quarry being smaller on average with respect
to other C. lobatus.
Coefficients of variation, a standard measure of the relative
amount variation in a sample, for P4 through M3 of the
Coryphodon from Deardorff Hill Coryphodon Quarry are
given in Table 2. Simpson et al. (1960) noted that coefficients
of variation for mammalian species characteristically range
between 4 and 10. Gingerich and Schoeninger (1979) observed
a more narrow range of approximately 6 to 9 for P4, Ml, M2,
and M3 for primates, while Gingerich and Winkler (1979)
observed a slightly broader range of approximately 3 to 1 2 for
the same teeth in the red fox ( Vulpes vulpes). The Coryphodon
from Deardorff Hill Coryphodon Quarry have CV values
ranging from approximately 4 to 11. Variation in specimens
from Deardorff Hill Coryphodon Quarry is within an
acceptable range for a species of Coryphodon, especially given
that this taxon is sexually dimorphic.
Age Determination
Lucas and Schoch (1990) and Lucas (1984) proposed a dental
eruption sequence in Coryphodon that is confirmed by the C.
lobatus specimens from Deardorff Hill Coryphodon Quarry. In
addition, the specimens from this quarry permit us to fine-tune
some of the details of the eruption sequence. We observe the
following at Deardorff Hill Coryphodon Quarry (Figure 5):
• None of the anterior deciduous dentition is intact in the
Deardorff Hill Coryphodon Quarry specimens. Lucas and
Schoch (1990) believe that the anterior deciduous dentition
precedes the posterior deciduous dentition. Given the teeth
present in the Deardorff Hill Coryphodon Quarry speci¬
mens, we believe that the deciduous premolars dP4, dP3,
and dP2 erupt sequentially, starting with the dP4.
• The first molar (Ml) erupts next at about the same time as
13 and followed by the last of the deciduous teeth, the dPl.
Unlike other deciduous teeth, the dPl is retained in the
adult dentition.
• The M2 erupts next, followed by the permanent premolars
P4, P3, and P2, which replace the deciduous premolars.
• The II probably erupts next, followed by the adult canine,
12, and M3, which erupt at approximately the same time.
From the Deardorff Hill Coryphodon Quarry specimens, we
can determine that these teeth erupt simultaneously,
whereas previously it was suggested that the 12 and M3
erupted after the canine.
As in other mammals, deciduous teeth are identified by their
weak or flaring roots, a light brown color, and thin, less rugose
or striated enamel. Corresponding teeth of the upper and
lower dentition erupt at the same time. These patterns and
Fig. 5. Dental eruption sequence for Coryphodon. Data from Deardorff Hill Coryphodon Quarry confirm postulated sequence of Lucas and
Schoch (1990). After Lucas and Schoch (1990).
MCGEE AND TURNBULL: CORYPHODON LOBATUS FROM DEARDORFF HILL CORYPHODON QUARRY 5
Fig. 6. (A) Coryphodon lobatus , PM 39436, mandible with LdP2^r-
M], (B) C. lobatus , PM 39381, maxillary fragment with RdP1 4, M1.
Deciduous premolars still present and First permanent molar present. 13
is in the process of erupting (indicated by arrow in Fig. 6A). Deardorff
Hill Coryphodon Quarry contains four individuals from age class 1 that
are nearly identical in eruption and wear patterns. This suggests these
individuals were the same age at death and therefore were born at the
same time of year (i.e., births could have been seasonal).
characteristics are verified here and also reported by Lucas
and Schoch (1990).
We group the C. lobatus specimens from Deardorff Hill
Coryphodon Quarry into five age classes. The first three classes
are distinguished by eruption sequences, while the last two
classes are differentiated on the basis of wear.
Age Class 1 (young subadult)
(Figure 6)
Deciduous premolars are still present, and the first permanent
molar is fully erupted; 13 is in the process of erupting (arrow,
Figure 6). Specimens in age class 1 include the following:
PM 39436 (LdP2_4-Mi): M] is fully erupted and 13 is
partially erupted. An alveolus is present for dPi but the tooth
is missing. The dP2_4 are well worn; the Mi shows minimum
wear, appearing as a shear surface along the metalophid.
PM 39381 (RdCP1 4-M'): Permanent right I3 in the crypt
exposed through breakage, suggesting that this would be the
next tooth to erupt (possibly in advance of M2).
Fig. 7. (A) Coryphodon lobatus , PM 39605/39665, skull with LI3?,
LdP4, LM1 - and RP3-M2. (B) C. lobatus, PM 39702, mandible with
LdP), LdP3^HVl2 and RI3?, RdPi^HVL. These specimens represent
age class 2. The second permanent molar is partially erupted; third
and fourth permanent premolars in process of erupting (indicated by
arrow in Fig. 7A).
PM 35879 (LdP^-M1): Possibly from the same individual
as PM 39381. These two specimens are very similar in eruption
and wear stage to PM 39436.
PM 39686 (LdP'^-M1): Similar in eruption and wear to
PM 39436, PM 39381, and PM 35879. This specimen preserves
the area posterior to the M1, and there is no evidence of the
M or even a crypt for M .
PM 39375 (LdP] 3, LMb and RMQ: M, and dP! are fully
erupted. The crypt of the M2 is visible, but no tooth is apparent.
It is also uncertain if the P4 was shed or fell out postmortem.
LdPj_3 are present with wear (dP4 is missing, but the alveolus is
present and well defined), and there is no wear on Mb The
presence of the M2 crypt suggests that this individual was older
than PM 39686, PM 39436, PM 39381, and PM 35879.
Deardorff Hill Coryphodon Quarry contains four individuals
from this class (PM 39686, PM 39436, PM 39381, and PM 35879)
that are nearly identical in eruption and wear patterns. This
suggests the same age at death and thus would have been bom at
the same time of year. Although these four are the youngest in
the assemblage, the presence of the permanent Mj suggests that
even the youngest individuals in this Coryphodon herd were
probably weaned and that births could have been seasonal. In two
extant analogues of Coryphodon — Sus scrofa and Hippopotamus
amphibius — subadults are weaned (3.38 months and 10.13
months, respectively; Ernest, 2003) before the first molar has
completely erupted (5.6 months and 24 months, respectively;
Smith, 2000).
6
FIELDIANA: GEOLOGY
Fig. 8. (A) Coryphodon Iobatus, PM 39385, skull with LC-M3;
RC, P2-M3. (B) C. Iobatus, PM 35873, mandible with LL-M3, Rfi-C,
P2-M3. These specimens represent age class 3. Permanent canine and
third molar partially erupted, and the adult second incisor (one of the
last teeth to erupt in adult dentition) is also erupting.
Fig. 9. (A) Coryphodon Iobatus, PM 35870 skull with L/C, LP2 4,
LM1 3, RP2 4, RM1 . (B) C. Iobatus , PM 35865 (mandible with Lf 2,
P1-M3, RI2-I3, P1-M3 and associated lower LC and LI3 not
pictured). All teeth present are part of the permanent dentition
(dPl is retained). First and second molars are worn (especially the
Ml); incisors also show wear.
Age Class 2 (subadult)
(Figure 7)
PM 39702 and PM 39605/39665, which may represent the
same individual, are considered a subadult:
PM 39702 (mandible with LdP], LdP3^-M2 and RI3?,
RdP]^-M2): Mi and dP^ are fully erupted and show some
wear. The M2 is partially erupted. On the left, a permanent
premolar is partially exposed under the dP4. There is a very
small alveolus anterior to the right dP1? presumably for a
deciduous canine; the left side of the mandible is too badly
damaged to determine the status of this area. There is a large,
spatulate tooth anterior to this alveolus, which is interpreted
to be the RI3.
PM 39605/39665 (skull with LI3?, LdP4, LM1"2, and RP3-
M2): As with PM 37902, the M1 shows some wear and the M2
is partially erupted. Permanent premolars are partially
exposed under the LdP3, LdP4, RdP3, and RdP4.
Age Class 3 (young adult)
(Figure 8)
PM 35873 and PM 39385 are considered young adults:
PM 35873: The C and M3 are partially erupted on both
sides. The anterior dentition of this specimen is unusual in that
there are three fully erupted and worn incisors that appear to
be part of the adult dentition, but there is also another incisor
erupting into the position occupied by RI2; it is unknown
whether this tooth is supernumerary or if it is an adult incisor
displacing the dI2. (This confirms Lucas’s observation that the
12 is the last incisor to erupt.) All other teeth present in the
mandible are permanent. The canines are about 28.71 mm
(right side) at the gum line, but the dentary is broken away to
expose the rest of the canine (on both sides), which appears
large. PM 39385 is a skull that similarly has partially erupted
M'1 and almost fully erupted canines; the incisors are not
preserved in this specimen.
Age Class 4 (adult)
(Figure 9)
In age class 4, all of the adult teeth are erupted:
PM 35870 (dentary with LP^Mi, associated lower LC and
two incisors, and skull with LC, LP2"4, LM1"3, RP2 4, RM1"3):
All teeth are part of the permanent dentition. The protoconids
and hypoconids on the lower Ml and M2 are worn (especially
in Ml). In the skull, the protocones and postprotocristae of
the Ml and M2 are similarly worn; the third molar, which is
present in the skull but absent in the dentary fragment, shows
only the beginning stages of wear. The permanent premolars
are not significantly worn in either the skull or the dentary
fragment.
PM 35865 (mandible with LI i_2, LPi-M3, RI2-I3, RP]-M3
and associated lower LC and LI3): All teeth are part of the
permanent dentition. There is a small amount of wear on the
RM3; wear increases anteriorly from M3 to M,. P4 is not worn.
MCGEE AND TURNBULL: CORYPHODON LOBATUS FROM DEARDORFF HILL CORYPHODON QUARRY 7
but P3 is. The left dentary of this mandible is similar in wear
features except that the P4 is more worn than the P3, and
overall there is considerably more wear on the teeth on the left
than on the right. There is a fair amount of wear on RI3 and to
a lesser extent, RI2; on the left side, Ij shows more wear than
I2.
PM 35903 (skull with LP2-M3 and RP2-M3): The lower and
upper Ml are very worn, and the protoloph and ectoloph on
M3 are fairly worn.
PM 35871 (skull with LI-M3, RI2-C, RP2-M3) and PM
35878 (mandible with LIi-M3, R 1 1— 12-> RC-M3): The proto-
cone of the M is moderately worn, along with the protoloph
and ectoloph; as with PM 35903, the upper and lower first
molar are very worn. The left and right I3 in PM 35871 are the
most worn of the upper incisors; on the lower dentition (PM
35878), the I2 are the most worn of the incisors.
Age Class 5 (advanced/old adult)
As with age class 4, in age class 5, all of the adult teeth are
erupted. Age class 5 exhibits extreme wear on many of the
teeth:
PM 39673 (skull with LI3, LC, LP2 M3 and RI3, RC, RP2-
M3), PM 39374 (LI, 2, LP2-M3, and RI)_2, RP)-M3), and
PI 5628 (mandible with LIi-M3, and RI)-M3 and skull with
LI1”3, LC, LP2-M3, RI1 3, RC, RP2-M3) are the most worn of
the specimens. Both upper and lower Ml and M2 are
extremely worn, and M3 is beginning to show excessive wear
along the metalophid and protoconid/hypolophid on the
lowers; in the uppers, the protoloph and ectoloph are
completely worn. There is still enamel present elsewhere on
the occlusal surface of both the upper and lower M3; there is
almost no enamel left on the occlusal surfaces of the upper and
lower Ml and M2. The P3 and P4 are also well worn
(especially in the lower dentition).
Aspects of Coryphodon Life History
The preservation of the eruption sequence of the Deardorff
Hill Coryphodon provides an opportunity to consider life
history characteristics of Coryphodon. Smith (2000) suggests
that relative eruption sequences of select extant taxa can be
used to predict the tempo of life histories for species of extinct
mammals. She examined eruption sequences in Insectivora,
Archonta, and Ungulata to test “Schultz’s Rule” that
permanent incisors, canines, and premolars (= replacement
teeth) erupt earlier in slow-growing, long-lived species. She
noted that in rapidly growing mammals (e.g., Antidorcas), the
three sets of teeth (deciduous, molars, and replacement) erupt
sequentially (deciduous — * molars — > replacement), whereas in
slow-growing mammals (e.g.. Homo), the eruption of molars
and replacement teeth is mixed (e.g., the permanent canine
erupts after Ml and before M3, as in the case of the collared
peccary, Tayassu tajcicu). Age classes 1 and 2 of C. lobatus
from Deardorff Hill Coryphodon Quarry clearly indicate a
sequence in which the molars and replacement teeth are mixed,
a pattern that is suggestive of a prolonged development.
Framing Coryphodon evolution within the context of life
histories, as suggested by Smith (2000) also leads us to consider
which, if any, large-bodied extant herbivore is a good analogue
for this taxon. Within the “slow growers,” Smith (2000)
34
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M3 length (mm)
Fig. 10. Metric variation in the lower third molar of Coryphodon
lobatus from Deardorff Hill Coryphodon Quarry compared with lower
third molar of C. anthracoideus from Roehler’s Coryphodon
Catastrophe Quarry. Both death assemblages indicate the presence
of large- and small-size morphs in each assemblage, presumed to
indicate males and females, respectively.
■ Deardorff Hill Coryphodon Quarry
A Roehler's Coryphodon Catastrophe Quarry
A A
suggested that Coryphodon is less like the hippo and more like
a large deer or pig. She noted that the eruption patterns of I)
and P3 seen in Coryphodon are found in extant mammals in
which the Mj erupts between 0.34 and 0.88 years and that have
a life span of 21 to 35 years. She questions whether the hippo,
with a slower life history marked by the emergence of the Ml at
two years and a life span of 40 to 50 years, is a suitable analogue
for Coryphodon. Coryphodon shares a sequence pattern
M]M2P3M3 with Equus burchelli, T. tajacu, S. scrofa, H.
amphibius , Ceratotherium simum, and Procavia capensis. We
add to this the observation that all these taxa, with the
exception of E. burchelli , wean their young before the complete
eruption of the first molar (Smith, 2000; Ernest, 2003). These
observations serve to underscore the complexity of identifying
an analogue. In putting Coryphodon in the context of an extant
species, Lucas (1984) discussed functional analogues such as the
pygmy hippo ( Hexaprotodon liberiensis ), tapirs ( Tapirus sp.),
and the Sumatran rhino (Dicerorhinus sumatrensis ) as well as
ecologic analogues such as the hippo ( H . amphibius). Dental
eruption data suggest that life history can also serve as a basis
for analogy between extant and extinct taxa.
Sociality in Coryphodon and Future Directions
Death or catastrophic assemblages such as Deardorff Hill
Coryphodon Quarry potentially provide a unique window into
the behavior of extinct populations. A paleopopulation,
defined as a well-delimited faunal level spanning a short
period of geological time (MacFadden, 2008), may still
represent as much as 100,000 years in duration. Mass death
assemblages, representing near instantaneous accumulation
(e.g., such as that seen over a period of days, weeks, or months
during wildebeest migrations when rivers are in flood; Talbot
& Talbot 1963), are more comparable to extant populations.
Mihlbachler (2003) argued that because adult sex ratios
(ASRs) are linked to sociality in extant species (Berger, 1986;
8
FIELDIANA: GEOLOGY
Byers, 1997), ASRs in fossil assemblages can be used to infer
paleodemography in extinct species if males can be distin¬
guished from females through sexually dimorphic features.
Sexual dimorphism in Coryphodon quarry assemblages is
evident in the size of the third molars and the canines
(Figure 10). We would expect this to be the case on the basis
of Gingerich’s (1974) suggestion that the third molar is under
greater influence of sex hormones than the first and second
molars, which erupt earlier. Sexual dimorphism can also be
inferred from canines. However, canines are often missing or
broken in Coryphodon assemblages that have undergone
significant postmortem modifications. Figure 10 indicates that
there are two distinct size morphs in the Deardorff Hill
Coryphodon Quarry assemblage, a pattern that is also seen in
the death assemblages of C. anthracoideus from Roehler’s
Coryphodon Catastrophe Quarry, and C. molestus from
AMNH Quarry 242. General consensus is that in extant large
herbivorous mammals, males are usually larger than females
(Ralls, 1977; Jarman, 1983), and this has been inferred for
fossil mammals (Kurten, 1969; Gingerich, 1981).
Ralls (1977) and Jarman (1983) argued that there is a close
correlation between sexual dimorphism and polygyny. Using
information on sexual dimorphism and body size differences
in C. lobatus from Deardorff Hill Coryphodon Quarry, we can
reconstruct a picture of sociality patterns. The ASR at
Deardorff Hill Coryphodon Quarry is minimally 1:3 (which is
also the case for C. anthracoideus at Roehler’s Coryphodon
Catastrophe Quarry). We would predict based on the model of
Berger et al. (2001) that C. lobatus lived in unisex groups
except during periods of the year when mating took place. The
ASR of the Deardorff Hill Coryphodon Quarry indicates that
males were present at the time the death event occurred, and
therefore this assemblage probably preserves a picture of this
population of Coryphodon during mating season.
The cranial and postcranial C. lobatus material from
Deardorff Hill Coryphodon Quarry is still largely unstudied
beyond basic inventorying, and thus many questions remain
regarding the degree and nature of sexual dimorphism in this
species. It has been suggested that extreme polygyny and
dimorphism are associated with bimaturism; that is, males and
females reach sexual maturity at different ages (Ralls, 1977;
Jarman, 1983). Jarman (1983) argued that a delay in male
maturation is in fact a requirement for the evolution of
extreme polygyny and sexual dimorphism. Coryphodon mass
death assemblages will no doubt be useful in eliciting the
degree of sexual dimorphism in this taxon and hence the
possibility that males matured later than females. Additional
work might also focus on a closer inspection of size differences
between the two morphs (i.e., males and females) in the
Deardorff Hill Coryphodon Quarry assemblage. With respect
to interpreting the behavioral and/or demographic significance
of sexual dimorphism, the distinction must be made between
dimorphism in secondary sexual characteristics and dimor¬
phism in body size. A number of authors have noted that
selection pressures including sexual selection may contribute
to sexual dimorphism in size (Ralls, 1977; Alexander et al.,
1979; Gingerich, 1981; Jarman, 1983; Weckerly, 1998). Ralls
(1977) suggests that sexual dimorphism in structures and
coloration is more closely related to sexual selection than is
body size. That is, different factors can cause dimorphism in
size (e.g., neonate size in females), but only sexual selection
can affect structure/coloration. Future analysis might test
whether Coryphodon males and females are different only in
size or if differences in morphology beyond allometry exist. If
males are relatively and absolutely larger than females, then it
may be the case that sexual selection is the driving force.
Acknowledgments
We would like to thank Bill Simpson (Field Museum) for
his invaluable assistance with this project, and John Weinstein
(Field Museum) for excellent photographic support. Drs.
Spencer Lucas (New Mexico Museum of Natural History and
Science) and Lawrence Flynn (Peabody Museum of Archae¬
ology and Ethnology) for excellent feedback on the manu¬
script. Many thanks to Dr. Allen Kihm for advice on the map
of the Piceance Creek Basin and to Arnaud Bergerol for
assistance with data entry.
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Mammalogy, 79: 33-52.
Appendix I. Metric measurements of lower adult dentition of Coryphodon lobatus from Deardorff Hill
Coryphodon Quarry (all measurements in mm)
PM 35878
PI 5628
PM 35865
PM 35873
PM
35870
PM 39374
Left
Right
Left
Right
Left
Right
Left
Right
Left
Left
Right
II
18.51
21.79
20.73
20.02
22.51
21.04
20.59
17.51
Iz
21.45
21.53
21.85
23.68
22.92
23.45
23.02
22.94
22.68
23.09
I3
20.51
19.54
18.23
23.26
19.48
24.90
23.95
C-bl
21.52
22.21
27.66
28.03
26.32
C-md
24.62
25.80
34.53
33.12
23.97
PiL
15.93
15.99
16.21
16.39
16.95
16.04
17.13
15.86
15.57
PiW
9.51
11.06
10.47
11.66
9.73
9.61
9.37
9.45
9.45
p->L
17.05
18.59
24.92
20.83
19.34
20.35
22.16
21.27
17.47
18.80
21.41
p2W
13.50
13.25
15.62
16.42
13.97
14.17
15.08
14.78
13.41
13.79
13.59
p3L
21.43
20.50
23.80
23.50
20.78
20.35
22.60
22.15
22.97
22.34
22.07
p3W
15.72
17.39
17.89
17.49
16.31
16.24
17.73
17.63
15.52
16.22
16.10
p4L
21.14
18.24
24.51
25.24
23.68
24.13
23.20
23.82
21.73
23.71
23.51
p4W
18.49
17.82
20.03
20.55
18.33
19.18
20.44
19.54
17.97
20.27
19.33
nqL
25.72
24.34
30.69
29.56
25.29
28.69
29.01
29.99
25.08
25.08
24.71
nt] AW
20.58
19.06
20.47
20.89
18.92
19.40
20.72
19.64
20.49
22.80
21.70
m,PW
21.49
19.68
21.44
25.53
20.42
20.16
21.12
20.44
19.96
21.16
20.61
m->L
35.24
31.76
36.09
37.12
35.70
37.18
39.18
38.60
30.17
32.42
29.60
mAW
23.78
24.92
26.26
31.65
24.73
24.43
25.99
25.61
24.20
27.08
24.58
m-iPW
24.58
24.91
26.67
28.57
23.48
24.61
26.47
26.17
22.97
25.05
22.95
m3L
34.87
37.68
45.93
42.32
39.84
39.48
36.49
35.62
m,AW
26.82
27.44
31.01
27.42
26.00
26.21
29.84
26.48
27.28
27.09
m3PW
25.54
25.04
26.45
28.02
23.55
23.49
24.87
24.14
10
FIELDIANA: GEOLOGY
Appendix II. Metric measurements of upper adult dentition of Coryphodon lobatus from Deardorff Hill
Coryphodon Quarry (all measurements in mm)
PM 35871
PM 39385
PM 35903
PM 39673
PM 35870
PI 5628
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
11
21.81
24.54
24.97
12
21.31
20.06
25.90
23.27
13
19.63
17.88
19.01
15.22
23.35
22.35
C-bl
23.42
23.57
27.40
27.27
23.46
21.86
29.75
31.13
32.95
C-md
21.93
21.56
19.48
18.69
21.27
21.68
23.81
29.02
30.54
p'L
14.31
P w
10.80
11.20
p;L
18.14
18.37
19.34
19.22
21.82
21.85
20.18
19.85
18.05
18.61
20.53
20.39
pW
28.56
26.64
28.74
29.21
24.80
26.49
27.64
28.50
27.11
26.40
28.59
26.79
PL
19.78
18.87
21.75
21.56
21.81
20.88
19.34
19.63
19.33
19.63
23.49
23.64
p'W
30.21
30.61
30.99
31.43
28.70
29.15
31.41
29.33
29.71
29.09
33.24
32.52
p'L
18.47
17.83
20.98
20.43
19.77
18.90
17.99
18.46
20.46
20.55
22.51
22.42
p4W
31.39
31.45
32.50
31.66
30.96
30.65
30.59
31.70
31.41
32.15
34.58
33.32
m L
22.65
22.90
30.39
28.43
29.09
27.19
23.23
27.03
32.03
30.78
m'AW
30.92
30.11
30.54
30.07
31.03
29.08
32.19
27.79
31.43
34.83
mlPW
29.58
29.48
30.79
30.09
29.64
27.93
30.56
30.23
31.49
37.32
33.17
m2L
30.49
30.81
37.75
35.38
34.09
35.14
34.66
31.56
31.60
36.58
34.72
m2AW
37.22
38.11
37.33
37.99
38.41
37.64
40.54
37.70
37.65
39.75
38.89
m2PW
35.43
35.05
34.97
35.54
36.38
35.69
38.26
35.76
35.69
39.87
39.68
m3L
27.72
28.43
32.89
31.45
29.46
31.38
33.41
32.25
32.63
33.40
39.47
35.47
m3W
40.58
40.22
43.74
44.65
40.54
42.46
45.27
44.43
39.73
43.70
49.55
46.26
MCGEE AND TURNBULL: COR YPHODON LOB A TUS FROM DEARDORFF HILL COR YPHODON QUARRY 1 1
Appendix III. Metric measurements of juvenile dentition of Coryphodon lobatus from Deardorff Hill
Coryphodon Quarry (all measurements in mm)
PM 39375 left
PM 39375 right
PM 39702 left
PM 39702 right
PM 39436 left
II
h
h
20.30
C-bl
C-md
dp,L
16.03
14.15
15.46
dp, W
9.80
9.83
10.75
dp2L
12.16
15.78
dp2W
8.56
10.09
dp3L
17.60
18.15
19.11
dp3W
10.77
11.94
11.52
dp4L
20.81
26.71
dp4AW
14.79
14.17
dp4PW
17.30
15.69
niiL
29.75
29.99
25.68
25.33
32.57
ni] AW
18.64
17.77
21.26
19.13
20.61
m,PW
m->L
19.48
19.54
19.59
19.35
19.91
m,AW
26.07
23.76
m,PW
m3L
m3AW
m3PW
PM 39605/39665 left
PM 39605/39665 right
PM 39686 left
PM 39381 right
PM 35879 left
11
12
I3
20.42
C-bl
C-md
dp'L
16.00
16.34
dp W
13.91
10.54
dp2L
14.98
17.71
14.67
dp2W
15.32
14.55
dp'L
16.95
dp3W
18.87
18.26
17.01
dp^L
22.92
20.69
23.31
20.82
dp4W
25.64
24.79
23.73
23.29
m'L
27.42
27.56
27.69
29.29
31.21
m'AW
30.74
31.05
30.44
30.16
30.33
m'PW
28.71
31.15
26.37
30.54
m2L
30.33
31.31
m2AW
36.47
37.00
nrPW
38.27
35.32
m3L
m3W
12
FIELDIANA: GEOLOGY
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