Early Pliocene Leporids from the Gray Fossil Site of Tennessee
Joshua X. Samuels1,2* and Julia Schap1,2
1Department of Geosciences, East Tennessee State University, Johnson City, TN, USA. 2Don Sundquist Center of Excellence in Paleontology, East Tennessee State University, Johnson City, TN, USA. *Corresponding author.
Eastern Paleontologist, No. 8 (2021)
Abstract
The early Pliocene age Gray Fossil Site of Tennessee is one of the few late Neogene sites in eastern North America outside of Florida. Here, we describe two leporid species from the site: 1) a larger, less abundant Alilepus vagus and 2) a smaller, more abundant Notolagus lepusculus. Both species are well-known taxa with relatively broad geographic and limited stratigraphic ranges, making them useful in refining the age of the site. In contrast to the open habitats characteristic of the many other sites where these species occur, floral and faunal evidence from the Gray Fossil Site suggests it was a forested habitat with at least a partially-closed canopy. Forest-dwelling rabbits occur in much of the Eastern United States today, and the Gray Fossil Site rabbits were likely filling similar niches in the Pliocene. The cranial and dental morphology of the two species do not provide any evidence of niche partitioning, but the postcranial morphologies of the two taxa at the site are distinct, with the smaller taxon more cursorially-adapted than Alilepus.
Download Full-text pdf
No. 8 2021
Early Pliocene Leporids
from the Gray Fossil
Site of Tennessee
Joshua X. Samuels and Julia Schap
Eastern Paleontologist
EASTERN PALEONTOLOGIST
The Eastern Paleontologist (ISSN # 2475-5117) is published by the Eagle Hill Institute, PO Box 9, 59 Eagle Hill Road, Steuben,
ME 04680-0009. Phone 207-546-2821 Ext. 4, FAX 207-546-3042. E-mail: office@eaglehill.us. Webpage: http://www.eaglehill.
us/epal. Copyright © 2021, all rights reserved. Published on an article by article basis. Special issue proposals are welcome. The
Eastern Paleontologist is an open access journal. Authors: Submission guidelines are available at http://www.eaglehill.us/epal.
Co-published journals: The Northeastern Naturalist, Southeastern Naturalist, Caribbean Naturalist, and Urban Naturalist, each
with a separate Board of Editors. The Eagle Hill Institute is a tax exempt 501(c)(3) nonprofit corporation of the State of Maine
(Federal ID # 010379899).
Board of Editors
Richard Bailey, Northeastern University, Boston, MA
David Bohaska, Smithsonian Institution, Washington,
DC
Michael E. Burns, Jacksonville State University, Jacksonville,
AL
Laura Cotton, Florida Museum of Natural History,
Gainesville, FL
Dana J. Ehret, New Jersey State Museum, Trenton, NJ
Robert Feranec, New York State Museum, Albany, NY
Steven E. Fields, Culture and Heritage Museums, Rock
Hill, SC
Timothy J. Gaudin, University of Tennessee, Chattanooga,
TN
Russell Graham, College of Earth and Mineral Sciences,
University Park, PA
Alex Hastings, Virginia Museum of Natural History,
Martinsville, VA
Andrew B. Heckert, Appalachian State University,
Boone, NC
Richard Hulbert, Florida Museum of Natural History,
Gainesville, FL
Steven Jasinski, State Museum of Pennsylvania, Harrisburg,
PA
Chris N. Jass, Royal Alberta Museum, Edmonton, AB,
Canada
Michal Kowalewski, Florida Museum of Natural History,
Gainesville, FL
Joerg-Henner Lotze, Eagle Hill Institute, Steuben, ME
... Publisher
Jim I. Mead, The Mammoth Site, Hot Springs, SD
Roger Portell, Florida Museum of Natural History,
Gainesville, FL
Frederick S. Rogers, Franklin Pierce University, Rindge,
NH
Joshua X. Samuels, Eastern Tennessee State University,
Johnson City, TN
Blaine Schubert, East Tennessee State University, Johnson
City, TN
Gary Stringer (Emeritus), University of Louisiana,
Monroe, LA
Steven C. Wallace, East Tennessee State University,
Johnson City, TN ... Editor
♦ The Eastern Paleontologist is a peer-reviewed journal
that publishes articles focusing on the paleontology
of eastern North America (ISSN 2475-5117 [online]).
Manuscripts based on studies outside of this region that
provide information on aspects of paleontology within
this region may be considered at the Editor’s discretion.
♦ Manuscript subject matter - The journal w elcomes
manuscripts based on paleontological discoveries of
terrestrial, freshwater, and marine organisms and their
communities. Manuscript subjects may include paleo -
zoology, paleobotany, micropaleontology, systematics/
taxonomy and specimen-based research, paleoecology
(including trace fossils), paleoenvironments, paleobio -
geography, and paleoclimate.
♦ It offers article-by-article online publication for
prompt distribution to a global audience.
♦ It offers authors the option of publishing lar ge files
such as data tables, and audio and video clips as online
supplemental files.
♦ Special issues - The Eastern Paleontologist welcomes
proposals for special issues that are based on
conference proceedings or on a series of invitational
articles. Special issue editors can rely on the publis her’s
years of experiences in efficiently handling most
details relating to the publication of special issues.
♦ Indexing - The Eastern Paleontologist is a young
journal whose indexing at this time is by way of author
entries in Google Scholar and Researchgate. Its indexing
coverage is expected to become comparable to that
of the Institute's first 3 journals (Northeastern Naturalist,
Southeastern Naturalist, and Journal of the North
Atlantic). These 3 journals are included in full -text in
BioOne.org and JSTOR.org and are indexed in Web of
Science (clarivate.com) and EBSCO.com.
♦ The journal's staff is pleased to discuss ideas for
manuscripts and to assist during all stages of manu -
script preparation. The journal has a page char ge to
help defray a portion of the costs of publishing manu -
scripts. Instructions for Authors are available online on
the journal’s website (http://www.eaglehill.us/epal).
♦ It is co-published with the Northeastern Naturalist,
Southeastern Naturalist, Caribbean Naturalist, Urban
Naturalist, Eastern Biologist, and Journal of the North
Atlantic.
♦ It is available online in full-text version on the journal's
website (http://www.eaglehill.us/epal). Arrangements
for inclusion in other databases are being pur -
sued.
Cover Photograph: Selected leporid specimens from the Gray Fossil Site in Tennessee, including a lower 3rd premolar
(ETMNH 20522) of Alilepus, lower 3rd premolar (ETMNH 20520) and partial dentary (ETMNH 21233) of Notolagus,
and an astragalus (ETMNH 22421) and calcaneum (ETMNH 9708) of a small rabbit. Photograph © Joshua X. Samuels.
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
1
2021 EASTERN PALEONTOLOGIST 8:1–23
Early Pliocene Leporids from the Gray Fossil Site of Tennessee
Joshua X. Samuels1,2* and Julia Schap1,2
Abstract - The early Pliocene age Gray Fossil Site of Tennessee is one of the few late Neogene sites in
eastern North America outside of Florida. Here, we describe two leporid species from the site: 1) a larger,
less abundant Alilepus vagus and 2) a smaller, more abundant Notolagus lepusculus. Both species are wellknown
taxa with relatively broad geographic and limited stratigraphic ranges, making them useful in refining
the age of the site. In contrast to the open habitats characteristic of the many other sites where these species
occur, floral and faunal evidence from the Gray Fossil Site suggests it was a forested habitat with at least a
partially-closed canopy. Forest-dwelling rabbits occur in much of the Eastern United States today, and the
Gray Fossil Site rabbits were likely filling similar niches in the Pliocene. The cranial and dental morphology
of the two species do not provide any evidence of niche partitioning, but the postcranial morphologies of the
two taxa at the site are distinct, with the smaller taxon more cursorially-adapted than Alilepus.
Intoduction
Rabbits and hares (Leporidae) are key components of nearly every terrestrial ecosystem in
North America today, and have been so since the Eocene (Dawson 1958, 2008). The family is
known for being successful, and despite often being considered biologically conservative over
their history, they do exhibit some ecological and morphological variability (Chapman and Flux
2008, Kraatz et al. 2015). In North America, the diversity of Leporidae has been relatively low
and stable throughout the Cenozoic (Dawson 2008, Samuels and Hopkins 2017), but there was
a substantial increase in leporid diversity in the latest Miocene and early Pliocene. In the late
Pliocene, the family reached its current level of species diversity (Nowak 1999), and also had
greater generic diversity and morphological disparity (as indicated by p3 pattern, Dawson 2008,
Moretti 2018) than today. The few species present in fossil faunas are often particularly abundant
components, just as they are in modern communities (Hibbard 1969). Two of the most notable
adaptations of leporids today, hypselodont dentition and saltatory/cursorially-adapted postcrania,
appear very early in the family’s history, suggesting their general ecology has changed little since
the Oligocene (Dawson 1958, 2008; Samuels and Hopkins 2017). In general, most late Cenozoic
rabbits likely occupied small generalist-browsing, running-adapted niches (Armstrong et al. 2010,
Bittner et al. 1982, Dalke and Sime 1941, Peers et al. 2018).
Six leporid species currently live in eastern North America, including three in the southern
Appalachian Mountains region (Sylvilagus floridanus, S. obscurus, and Lepus americanus). While
abundant and relatively diverse now, there are few records of leporids from eastern North America
prior to the late Pleistocene. There is a single archaeolagine leporid, Hypolagus cf. H. fontinalis,
known from the early Pliocene (early Blancan) age Pipe Creek Sinkhole in Indiana (Farlow et al.
2001). The archaeolagines Hypolagus ringoldensis and Hypolagus cf. H. tedfordi and the leporine
Nekrolagus progressus have been noted from the late Miocene (Hemphillian) Palmetto Fauna
of Florida (Hulbert 2001, Webb et al. 2008; White 1987, 1991a). Several species of Sylvilagus
(specifically S. floridanus, S. palustris, and S. webbi) are known from a number of early Pleistocene
(late Blancan and early Irvingtonian) sites in Florida (Dawson 2008, Hulbert 2001,White 1991b).
1Department of Geosciences, East Tennessee State University, Johnson City, TN, USA. 2Don Sundquist
Center of Excellence in Paleontology, East Tennessee State University, Johnson City, TN, USA.
*Corresponding author: samuelsjx@etsu.edu
Manuscript Editor: Richard Hulbert
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
2
Lepus has also been noted in Florida at Inglis 1A and Leisey Shell Pit, which are the and early
Pleistocene (late Blancan and Irvingtonian) in age (Hulbert 2001)
Here, we describe the leporids from the Early Pliocene (latest Hemphillian or early Blancan) age
Gray Fossil Site of Tennessee. The specimens described here represent the only Neogene records of
lagomorphs from the Appalachian region and the first reported occurrences of the genera Alilepus
and Notolagus in the eastern part of North America. Both of the leporids at the Gray Fossil Site
are particularly useful for biostratigraphic age assignment and conteribute to the recently revised
estimate of age of the site (Samuels et al. 2018).
Materials and Methods
Fossil rabbit specimens are typically identified and diagnosed based on the pattern of enamel
reentrants in the lower third premolar (p3) (e.g., Dawson 1958, 2008; Dice 1929, White 1987, 1991a),
and the upper second premolar (P2) is also taxonomically informative. Upper teeth are indicated
by capital letters (e.g., M1) and lower teeth by lower case letters (e.g., m1). Dental nomenclature
used here follows several sources (Čermák et al. 2015, White 1987, 1991a). Abbreviations of terms
commonly used to describe the morphology of the p3 are as follows: AER = anteroexternal reentrant,
AIR = anterointernal reentrant, AR = anterior reentrant, PER = posteroexternal reentrant, PIR =
posterointernal reentrant. Measurements of the teeth, to the nearest 0.01 mm, were made using
Mitutoyo Absolute digital calipers. Measurements of upper teeth include anteroposterior length
and transverse breadth; for lower teeth they include anteroposterior length and transverse breadth
of the trigonid (Wtri) and talonid (Wtal). Additional measurements, based on White 1991a, were
taken from photographs using ImageJ (Rasband 2007). Measurements and dental terminology used
are illustrated in Figure 1. Postcranial measurements include the following: HEW = epicondylar
width of the humerus, HartW = maximum distal articular width of the humerus, TibDW = maximum
mediolateral width of the distal tibia , TibDD = maximum anteroposterior depth of the distal tibia,
TibSW = minimum width of the tibia shaft near the distal end, AstL = maximum length of astragalus,
AstW = maximum mediolateral width of astragalus, CalL = maximum length of calcaneus, CalW
= maximum mediolateral width of calcaneus at the level of the sustentaculum, CalTL = maximum
length of calcaneal tuber from proximal tip of the tuber to the proximal end of the ectal prominence,
CalTW = maximum width of the calcaneal tuber at its proximal end, CalBL = maximum length of
the calcaneal body from the distal end of the ectal prominence to the distal-most point of the body;
hindlimb were modified from those presented in Fostowicz−Frelik (2007). Fossil specimens were
photographed using either a DinoLite Edge AM4815ZT digital microscope camera or a Nikon
D810 DSLR camera with a AF-S Micro Nikkor 60mm lens.
All specimens described here are housed at the East Tennessee State University Museum of
Natural History (ETMNH), Gray, Tennessee. Material was compared to modern leporid specimens in
the ETMNH collection, including: Sylvilagus audobonii (ETVP CC255, 2540, 5101, 10363, 10433),
S. floridanus (ETVP 5767, 7021), Lepus californicus (ETVP 134, 2563, 11667), and Brachylagus
idahoensis (ETVP 2586, 2589). Fossil specimens examined include Hypolagus and Alilepus from
the Glenns Ferry Formation in several collections (National Museum of Natural History - NMNH,
Hagerman Fossil Beds National Monument - HAFO, Natural History Museum of Los Angeles
County - LACM), and specimens of Notolagus in the LACM collection. Material was also compared
to specimens and measurements in a wide range of publications (including Averianov 1995,
Campbell 1969, Čermák et al. 2015, Hibbard 1969, Moretti 2018, White 1991a, White and Morgan
1995). Complete measurement data for all leporids studied are included in Supplemental Tables 1
and 2 (available online at https://eaglehill.us/epalonline/suppl-files/epal-008-samuels-s1.pdf and
https://eaglehill.us/epalonline/suppl-files/epal-008-samuels-s2.pdf).
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
3
Geological Setting
The Gray Fossil Site of northeast Tennessee was formed as an ancient sinkhole with a small,
deep lake that filled with sediment over approximately 4,500 to 11,000 years (Shunk et al. 2006,
2009). The sediments in the upper lacustrine strata include a series of rhythmites, with alternating
layers of fine-grained silty clay and coarse-grained, organic rich sediments (Shunk et al. 2006,
2009). The site includes an amazingly diverse and well-preserved fauna and flora (e.g., Mead et al.
2012, Parmalee et al. 2002, Ochoa et al. 2012, 2016; Worobiec et al. 2013, Wallace and Wang 2004,
Zobaa et al. 2011). The flora includes both macro- and microfossils that indicate the presence of a
forest dominated by oak (Quercus), hickory (Carya), and pine (Pinus), accompanied by variety of
herbaceous taxa (Ochoa et al. 2016, and references therein). Multiple palynology studies (Ochoa et
al. 2012, 2016; Zobaa et al. 2011) have found almost no grass (Poaceae) pollen at the site, strongly
indicating grass-dominated habitats were not present in close proximity. Presence of tupelo (Nyssa)
and bald cypress (Taxodium) leaves and pollen at the site also suggest humid riparian or wetland areas
occurred at the site (Brandon 2013, Worobiec et al. 2013). Based on the flora, Ochoa et al. (2016)
interpreted the site as a woodland or woodland savanna environment with frequent disturbance.
Carbon and oxygen isotopic analyses from ungulate and proboscidean teeth from the site support the
presence of relatively dense forest, but a single proboscidean specimen suggested more open grassdominated
habitats occurred nearby, at least within the dispersal range of an individual, which might
have been hundreds of kilometers (DeSantis and Wallace 2008). Isotopic analyses also suggest the
climate had little seasonal variation in temperature and precipitation (DeSantis and Wallace 2008).
The fauna includes multiple taxa that indicate the presence of aquatic environments, specifically
fish, neotenic salamanders, aquatic turtles, Alligator, and beavers (Boardman and Schubert 2011,
Bourque and Schubert 2015, Jasinski 2018, Mead et al. 2012, Parmalee et al. 2002). The site also
Figure 1. Schematic illustration of a leporid p3 indicating measurements taken for each specimen.
Measurements follow White, 1987.
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
4
has several vertebrate taxa that are intolerant of freezing conditions (Alligator, Heloderma) (Mead
et al. 2012, Parmalee et al. 2002), and others characteristic of forested habitats (tree squirrels, flying
squirrels, Tapirus, Bassariscus, and Pristinailurus) (Crowe 2017, Hulbert et al. 2009, Samuels et
al. 2018, Wallace and Wang 2004). Combined, the flora and fauna at the site present a truly unique
combination among North American biotas (Hulbert et al. 2009, Wallace and Wang 2004).
The estimated age of the Gray Fossil Site was recently revised based on a number of newly
identified taxa, which have good fossil records and limited stratigraphic ranges (Samuels et al. 2018).
Of the genera at the site, none is restricted to the Miocene or the Hemphillian NALMA and multiple
taxa are characteristic of Blancan faunas. Based on the presence of the rhino Teleoceras, dromomerycid
Pediomeryx, mephitid Buisnictis breviramus, leporids Alilepus and Notolagus (described here), and
the cricetids Neotoma, Repomys, and Symmetrodontomys, the age of the site is estimated to be Early
Pliocene, between 4.9 and 4.5 Ma, near the Hemphillian-Blancan transition (Samuels et al. 2018).
Previous records of the species described here, and the associated geographic and chronologic data
were derived from the MIOMAP/FAUNMAP Databases (Carrasco et al. 2007, Graham and Lundelius
2010, www.ucmp.berkeley.edu/neomap/), NOW Database (Fortelius 2013, pantodon.science.helsinki.
fi/now/), and recent publications (e.g., Moretti 2018), these records are outlined in Supplemental Table
3 (available online at https://eaglehill.us/epalonline/suppl-files/epal-008-samuels-s3.pdf).
Results
Systematic Paleontology
Class MAMMALIA Linnaeus 1758
Order LAGOMORPHA Gidley 1912
Family LEPORIDAE Gray 1821
Subfamily LEPORINAE Trouessart 1880
Genus ALILEPUS Dice 1931
Alilepus vagus Gazin 1934
(Figure 2, Tables 1–2, Supplemental Tables 1 and 2)
Referred Specimens—ETMNH 9765, left dentary with m2; ETMNH 20522, 22423, p3; ETMNH
9698, 9699, 9702, 20521, 21240, lower molariform teeth (p4–m2); ETMNH 9691, 13809, P2; ETMNH
9672, 9701, 9703, 9706, 18431, 18438, 20505, 20513, 20603, 21239, upper molariform teeth (P3–M2).
Locality—Gray Fossil Site, Washington County, Tennessee.
Age—Early Pliocene (earliest Blancan).
Description—The dentary (ETMNH 9765) is incomplete and bears only a single tooth, the m2; the
incisor and all other premolars and molars are missing (Figure 2 E–F). The preserved portion of the
dentary is fairly complete, with alveoli for the incisor and all of the cheek teeth preserved. The horizontal
ramus is complete and preserves the anterior portion of the masseteric fossa, but the mandibular angle,
coronoid process, and articular (condyloid) process are all missing. The mandibular symphysis is
clearly defined, with a highly rugose portion directly adjacent to the incisor alveolus and a subtle, but
distinct ridge running posteriorly along the ventral margin of the diaphyseal portion of the horizontal
ramus, ending below the anterior margin of the p3. The lower incisor root terminated just above and
posterior to that ridge, below the p3, and a bulging capsule surrounding the root is evident despite
breakage. The lateral surface of the diaphysis bears multiple mental foramina, including prominent
foramina along the dorsal and ventral margins of the diaphysis anterior to the p3. The masseteric fossa
has a clearly defined margin, though only the ventral portion of the fossa is delimited by an elevated
ridge. The anterior margin of the masseteric fossa is curved and somewhat angular.
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
5
While the p3 is not preserved in this dentary, aspects of its morphology allow referral of the
specimen to Alilepus. The preserved alveolus for the p3 has a prominent ridge marking the location
of the PIR (Fig. 2E, F), which matches the size and position of that structure in other specimens
of Alilepus. In contrast, for the few specimens of Notolagus with the PIR preserved it is more
anteriorly placed and in that taxon there is also a similar ridge for the AIR. Archaeolagines, like
Hypolagus, lack internal reentrants on the p3 entirely, and other leporines studied lack ridges
marking the location of internal reentrants. The m2 in ETMNH 9765 does not have the prominent
crenulations present in Pratilepus (Hibbard 1939, 1969). Additionally, the dimensions of the
dentary are similar to smaller specimens of Alilepus (Table 2). The size of the m2 within the
dentary, as well as the alveolus of the p3 and other teeth, are consistent with the size of the other
teeth referred here to Alilepus vagus.
In the p3 (ETMNH 20522, 22423, Figure 2 A–B) the anteroconid is relatively triangular and
pointed. There is not a distinct paraflexid (AIR) or anteroflexid (AR) present. In both specimens,
very shallow depressions along the anterior and lingual margins of the anteroconid, which extend
to the base of the tooth, suggest an incipient paraflexid (AIR) and anteroflexid (AR) are present;
these structures are more distinct in ETMNH 22423 highlighted in Figure 2B. The protoflexid
(AER) is shallow and crosses about 1/3 of the tooth. The hypoflexid (PER) crosses about half of
the tooth in both specimens, but in ETMNH 20522 its medial portion curves posteriorly and the
enamel along its posterior margin is somewhat crenulated, while it is straight and not crenulated
in ETMNH 22423. The mesoflexid (PIR) is straight and crosses about 1/3 of the tooth in both
specimens. The protoflexid (AER), hypoflexid (PER), and mesoflexid (PIR) all contain cementum.
Figure 2. Specimens of Alilepus vagus from the Gray Fossil Site, Tennessee. A. ETMNH 20522, R
p3; B. ETMNH 22423, L p3; C. ETMNH 9691, L P2; D. ETMNH 13809, L P2; E-F. ETMNH 9765, L
dentary with m2: E, lateral view; F. occlusal view. Scale bars equal 1 mm for A-D and 5 mm for E-F. In
Figure 2B, the incipient paraflexid (AIR) and anteroflexid (AR) a re indicated by arrows.
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
6
Under the system utilized by Čermák et al. (2015, and sources cited therein), ETMNH 20522 has
the A0/PR1/Pa0 p3 morphotype, though if the paraflexid (AIR) and anteroflexid (AR) in ETMNH
22423 are considered distinct reentrants then that specimens is the A1/PR1/Pa1 p3 morphotype.
In addition to the dentary and p3 specimens, five lower molariform teeth are also referred to
this taxon. As in the m2 in the dentary of ETMNH 9765, these other referred lower molariform teeth
(p4–m2) lack crenulations. The widths of these teeth are similar to the widths of the two described
p3 specimens from GFS, as well as the alveoli for p4–m2 within ETMNH 9765.
In the P2 (ETMNH 9691, 13809, Figure 2 C–D) the lingual portion (hypercone) is roughly
triangular in shape, and the labial portion (lagicone) is rounded. The tooth has two anterior reentrants,
a deep paraflexus (MAR) and shallow, but distinct mesoflexus (EAR) (morphotype B, Čermák et
al., 2015). Neither reentrant is crenulate, but both are filled with cementum, and that cementum
actually covers most of the anterior surface of the tooth. The distal portion of the paraflexus curves
strongly labially. There is no hypoflexus, but the anterolingual portion of the hypercone is flattened
(morphotype III, Čermák et al., 2015). In addition to the P2 specimens, ten upper molariform
teeth are referred to this taxon based primarily on their size, with widths proportionate to the P2
specimens and similar to p3 specimens from GFS.
Remarks—The sizes of ETMNH 20522 and 22423 (Table 1) fall within the range of variation
for the p3 of Alilepus vagus documented previously (Hibbard 1969, White 1991a). The morphology
of the p3 is also consistent with A. vagus, showing distinct similarity to well-documented samples
like those from the Hagerman local fauna in Idaho (Gazin 1934, Hibbard 1969, Ruez 2009). Large
samples from the Glenns Ferry Formation show some variation in morphology, particularly in
the structure of the mesoflexid (PIR), which is in some cases a deep, distinct reentrant (as in both
ETMNH specimens) and in others a closed mesofossettid (enamel lake). That variation, with some
p3s displaying a mesoflexid and others a mesofossettid is even apparent within a single individual,
as Hibbard (1969) described for the left and right p3 in a fused mandible from Hagerman (USNM
23574).
The GFS P2 specimens (ETMNH 9691, 13809) have two anterior reentrants, a deep paraflexus
(MAR) and shallow mesoflexus (EAR), as is characteristic of Alilepus (White 1991a). As in described
specimens of A. vagus (Hibbard 1969), the paraflexus (MAR) of the GFS specimens curves strongly
labially. The reentrants are filled with cement, as is the anterior surface of the tooth. These features
are all in contrast to the only other P2 in the sample from GFS, which is described below. While
two or three reentrants are variably observed in several fossil and extant leporine genera (White
1991a), several are only known from specimens with three anterior reentrants, including both
Pratilepus (Hibbard 1939) and Nekrolagus (White 1991a).
It is worth noting that the morphologies of the GFS p3 and P2 specimens are consistent
with other samples of A. vagus, but they are differentiable from other late Miocene and Pliocene
leporine species. The A0/PR1/Pa0 morphotype of the p3, as in the GFS sample, is also seen
in most Late Miocene members of the genus from North America (A. hibbardi), Eurasia (A.
annectens, A. elongatus, A. hungaricus, A. laskarewi, A. ucranicus), and Africa (A. sp.) (Čermák
et al. 2015, White 1991a, Winkler et al. 2011). It is important to note that the cranial and dental
morphology of A. hibbardi and A. vagus overlap, and the two species are also the same size
(White 1991a, Tables 1 and 2). White (1991a) indicated A. vagus was distinguished by a more
deeply incised PER than A. hibbardi (PER depth 51% or less width of p3). Ruez (2009) noted
that feature is variable in the large sample of A. vagus from Hagerman. In the GFS sample one
of the two p3 specimens (ETMNH 20522) does have a PER that is incised more than 51% the
width of the p3 (Supplemental Table 2), indicating it should be referred to A. vagus based on
the most recent diagnoses of these species (White 1991a). As was noted by Ruez (2009), the
only other character that has been used to distinguish between A. hibbardi and A. vagus is the
Eastern Paleontologist
J.X. Samuels and J. Schap
2021
7
No. 6
Table 1. Dental measurements (in mm) of Alilepus vagus and Notolagus lepusculus from the Gray Fossil Site, and a comparative sample of Neogene leporid
species. Note that measurements of unworn teeth are excluded from the table below. Measurements for other related taxa from White (1991). Complete listing of
measurements for all individuals in Supplemental Tables 1 and 2.
Taxon Source P2L P2W P3-M2L P3-M2W p3L p3W p4-m2L p4-m2Wtri p4-m2Wtal
Alilepus
vagus
Gray Fossil
Site, TN
Mean (n)
Minimum
Maximum
(2)
1.25
1.60
(2)
2.46
3.05
2.06(10)
1.77
2.47
3.66(10)
3.01
4.9
(2)
3.31
3.33
(2)
2.80
2.88
2.47(6)
2.27
2.91
2.87(6)
2.72
3.17
2.30(6)
1.95
2.73
Alilepus
vagus
White,
1991a
Mean (n)
Minimum
Maximum
3.2 (22)
2.4
3.8
3.0 (22)
2.1
3.7
Alilepus
hibbardi
White,
1991a
Mean (n)
Minimum
Maximum
3.3 (7)
3.0
3.4
3.0 (7)
2.6
3.3
Alilepus
wilsoni
White,
1991a
Mean (n)
Minimum
Maximum
2.6 (11)
2.4
2.7
2.3 (11)
2.0
2.4
Pratilepus
kansasensis
White,
1991a
Mean (n)
Minimum
Maximum
3.0 (25)
2.8
3.4
2.6 (25)
2.3
3.2
Notolagus
lepusculus
Gray Fossil
Site, TN
Mean (n)
Minimum
Maximum
(1)
0.87
(1)
1.64
1.40(10)
1.22
1.69
2.49(9)
1.82
3.12
2.68(5)
2.36
3.01
2.26(5)
1.94
2.63
1.80(5)
1.63
2.12
2.01(5)
1.75
2.27
1.61(5)
1.45
1.76
Notolagus
lepusculus
White,
1991a
Moretti,
2018
Mean (n)
Minimum
Maximum
Mean (n)
Minimum
Maximum
2.5 (27)
2.2
2.9
2.3 (12)
2.0
2.5
1.9 (28)
1.6
2.4
1.8 (12)
1.5
2.0
Notolagus
velox
White,
1991a
Mean (n)
Minimum
Maximum
3.0 (8)
2.3
3.4
2.4 (8)
1.7
2.6
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
8
Table 2. Dentary measurements (in mm) of Alilepus vagus and Notolagus lepusculus from the Gray Fossil Site, and a comparative sample of Neogene leporid
species. Measurements for other related taxa from White (1991) and Moretti (2018).
Taxon Source Mean/Range iW i – p3 Diastema L Cheek Toothrow L (p3 – m3) Dentary Depth at m1
Alilepus vagus
ETMNH 9765
Gray Fossil Site, TN 2.60 12.54 14.61 10.67
Alilepus vagus White, 1991a Mean
Minimum
Maximum
15.6
14.1
16.9
16.5
15.4
17.3
12.5
12.0
13.0
Alilepus hibbardi White, 1991a Mean
Minimum
Maximum
17.5 18.0 12.4
Alilepus wilsoni White, 1991a Mean
Minimum
Maximum
12.0
11.7
12.2
Pratilepus
kansasensis
White, 1991a Mean
Minimum
Maximum
14.2
13.6
15.0
13.5
13.2
13.8
13.5
13.2
13.8
Notolagus lepusculus
ETMNH 20524
Gray Fossil Site, TN 1.00 7.42
Notolagus lepusculus White, 1991a;
Moretti, 2018
Mean
Minimum
Maximum
9.7
10.7
9.3 11.6
Notolagus velox White, 1991a Mean
Minimum
Maximum
14.4
13.8
15.0
11.6
11.6
11.7
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
9
presence of an enamel lake on the P3 of A. hibbardi (White 1991a), but the occurrence of enamel
lakes in the upper premolars and molars is something that varies through wear of the tooth in
some leporids. Without large samples for study and assessment of intraspecific variability in that
trait, it may not be appropriate for use in differentiation of species. The other species of Alilepus
known from the latest Hemphillian and Blancan of North America, A. wilsoni, is rather different
from other members of the genus, with the mesoflexid (PIR) absent and the hypoflexid (PER)
extended across the tooth, resulting in the A0/PR0/Pa0 morphotype being present in all described
specimens (White 1991a, White and Morgan 1995). Ruez (2009) stressed how A. wilsoni bears
strong similarity to Aluralagus virginiae, as noted by White (1991a) in the original description,
and as such its taxonomy should be reassessed. The GFS specimens can be readily differentiated
from the Blancan age Pratilepus kansasensis, which has a much deeper protoflexid (AER) on the
p3 and more highly crenulate enamel in all reentrants (Hibbard 1939, Ruez 2009, White 1991a).
Several other leporine genera (Nekrolagus, Lepus, and Sylvilagus) are easily distinguished from
A. vagus by the lack of a PIR and presence of a much deeper PER (or adjacent enamel island) and
possession of a distinct cement-filled AR. Additionally, in contrast to the P2 of A. vagus from GFS,
the P2 of Pratilepus and Nekrolagus have three reentrants, including a shallow IAR (White 1991a).
The morphology of the dentary (ETMNH 9765, Fig. 2 E–F) is consistent with other described
specimens of Alilepus vagus (Hibbard 1969) and A. hibbardi (White 1991a), but it is smaller in
every measurement (Table 2) than any of the specimens reported by White (1991a). Smaller body
size in a population of rabbits living in a relatively densely forested environment is not particularly
surprising, as some leporids have previously been shown to follow Bergmann’s rule (Ashton et al.
2000, Davis 2019, Meiri and Dayan 2003).
cf. Alilepus sp.
(Figure 3, Table 3)
Referred Specimens—ETMNH 20502, distal left humerus; ETMNH 18440, distal left tibiofibula;
ETMNH 18434, left astragalus; ETMNH 8054, right calcaneum.
Locality—Gray Fossil Site, Washington County, Tennessee.
Age—Early Pliocene (earliest Blancan).
Description—The left humerus (ETMNH 20502) consists only of the distal extremity of the bone,
including the trochlea and medial epicondyle (Fig. 3A). There is no evidence of an epiphyseal plate,
indicating the specimen is from an adult individual, but some weathering/erosion is evident on the
margins of the trochlea and medial epicondyle. Overall, size and morphology of the element are
similar to that of larger specimens of Sylvilagus (Table 3), but there are some notable differences.
The distal articulation (trochlea) is like that of other studied leporids, with a prominent central groove
flanked by a pair of raised splines, though they are somewhat weathered in the fossil specimen.
The groove in ETMNH 20502 is shallower than in extant leporids studied and the lateral portion
of the articular surface is also relatively broader. Similarly, the medial epicondyle of ETMNH
20502, though worn, was clearly relatively larger than in extant leporids. The ratio of epicondylar
width of the humerus relative to distal articular breadth in ETMNH 20502 (HEW/HartW = 1.245)
is greater than in any of the extant taxa studied (HEW/HartW range from 1.152 to 1.218), as well
as the humeri of the smaller leporine present at the site (HEW/HartW = 1.162 and 1.169).
The tibiofibula (ETMNH 18440) has the distal portion preserved and there is no evidence
of an epiphyseal plate, indicating the specimen is from an adult individual (Figure 3G). Overall,
the morphology and proportions of the tibia closely resembles that of the specimens of A. vagus
described from Idaho (Campbell, 1969), as well as studied specimens of Sylvilagus audoboni and
S. floridanus. The distal articular facets of the tibiofibula are like those of extant leporines studied,
with a distally extended medial astragalar articular facet, deeply depressed lateral astragalar articular
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
10
facet, and distally extended calcaneal articular facet. The articular facets are the same width and
capable of articulation with the referred astragalus of cf. Alilepus sp. (ETMNH 18434). The medial
malleolus has a deep sulcus for the tibialis posterior muscle. The lateral malleolus is prominent
and the sulcus for the peroneus longus tendon is clear and prominent.
The left astragalus (ETMNH 18434) is incomplete, with the entirety of the astragalar head
and neck missing and some weathering/erosion evident on the anteroventral margin of the trochlea
(Figure 3C, D). The morphology of the trochlea is typical of extant leporids studied, with the
medial articular surface larger and longer than the lateral articular surface, a deep groove running
between the articular surfaces, and prominent splines running anteroposteriorly along each. Only
the posterior calcaneal articular facet is preserved, it is triangular in shape with its apex extending
laterally approximately half-way across the bone; that shape is similar to extant leporines like
Sylvilagus, Lepus, and Brachylagus, but is not typical of archaeolagines, where the facet is more
restricted to the medial aspect of the bone (Fostowicz-Frelik 2007).
Figure 3. Selected postcranial specimens of leporids from the Gray Fossil Site, Tennessee. Humerus:
A. ETMNH 20502, cf. Alilepus sp.; B. ETMNH 20518, Leporinae indeterminate. Astragalus: C-D.
ETMNH 18434, cf. Alilepus sp., C. dorsal view, D. ventral view; E-F. ETMNH 22421, Leporinae
indeterminate, E. dorsal view, F. ventral view. Tibia: G. ETMNH 18440, cf. Alilepus sp.; H. ETMNH
13805, Leporinae indeterminate. Calcaneum: I. ETMNH 8054, cf. Alilepus sp.; J. ETMNH 9708,
Leporinae indeterminate. Scale bar equals 2 mm.
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
11
Table 3. Postcranial measurements (in mm) of leporines from the Gray Fossil Site, and a comparative sample of Neogene leporid species. Measurements of Lepus
californicus, Sylvilagus floridanus, Sylvilagus obscurus, and Brachylagus idahoensis directly measured from specimens in the ETMNH collection. Measurements
for Alilepus vagus from Campbell (1969), Trischizolagus dumitrescuae from Averianov (1995), and Hypolagus beremdensis, Oryctolagus cuniculus, Pentalagus
furnessi, and Lepus europaeus from Fostowicz-Frelik (2007).
Taxon Source Specimen # HEW HartW TibDW TibDD TibSW AstL AstW CalL CalW CalTL CalTW CalBL
cf. Alilepus
sp.
Gray Fossil
Site, TN
ETMNH
20502
8.18 6.57
ETMNH
18440
9.05 4.92 4.91
ETMNH
18434
5.05
ETMNH
8054
23.57 8.54 10.72 5.55 9.20
Alilepus
vagus
Campbell
1969
Various 8.6-9.3 10.5-
13.2
6.2-7.5 11.4-
11.9
5.6-6.1 23.5-
24.5
5.8-6.6
Leporinae
Indeterminate
Gray Fossil
Site, TN
ETMNH
9709
6.90 5.94
ETMNH
20497
5.82
ETMNH
20498
5.05
ETMNH
20518
6.57 5.62
ETMNH
13805
8.37 4.36 4.61
ETMNH
9700
6.51 6.56 4.07
ETMNH
9708
17.23 6.74 7.43 4.18 6.77
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
12
Taxon Source Specimen # HEW HartW TibDW TibDD TibSW AstL AstW CalL CalW CalTL CalTW CalBL
ETMNH
21229
6.39 6.65 3.99
ETMNH
22421
9.42 4.14
Trischizolagus
dumitrescuae
Arverianov
1995
14.4 6.4 28.0
Hypolagus
beremendensis
Fostowicz-
Frelik 2007
13.1 6.6 6.8 14.1 6.4 26.4 9.5 12.4 6.3 10.2
Oryctolagus
cuniculus
Fostowicz-
Frelik 2007
12.4 5.3 5.9 11.9 6 23.0 8.1 11.2 6.2 8.5
Pentalagus
furnessi
Fostowicz-
Frelik 2007
15.9 6.8 7.6 13.7 8.1 27.0 11.8 13.0 7.6 9.0
Lepus
europaeus
Fostowicz-
Frelik 2007
16.4 8.8 7.6 17.3 8.1 34.5 11.7 17.4 8.3 12.6
Lepus
californicus
Various
(n=2)
10.70-
10.90
8.89-
9.16
13.65-
14.25
7.67-
7.91
6.45-
6.65
13.55-
14.00
6.79-
6.96
29.21-
30.20
9.24-
10.75
13.59-
15.08
7.11-
7.52
10.80-
10.99
Sylvilagus
audobonii
Various
(n=5)
6.67-
7.22
5.52-
6.19
8.61-
10.42
4.23-
4.94
4.47-
4.93
8.08-
9.69
4.21-
4.54
16.67-
19.59
6.21-
7.26
7.27-
8.28
4.06-
4.71
6.07-
7.73
Sylvilagus
floridanus
Various
(n=2)
7.68-
7.83
6.37-
6.53
10.52-
11.11
5.18-
5.31
4.64-
5.1
10.11-
10.47
4.90-
5.18
20.4-
22.06
6.80-
7.43
8.87-
8.99
4.63-
5.31
7.79-
7.85
Brachylagus
idahoensis
Various
(n=2)
5.49-
5.76
4.73-
4.75
7.29-
7.45
3.58-
3.96
3.43-
3.56
7.31-
7.36
3.48-
3.60
13.37-
13.46
4.87-
5.49
4.93-
5.25
2.97-
3.27
5.35-
5.54
Table 3, continued.
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
13
The right calcaneum (ETMNH 8054) is complete (Figure 3I), and similar in both size and
morphology to extant leporines studied. Notable differences between the calcaneum of ETMNH
8054 and extant taxa studied can be seen in the ectal prominence, ectal facet, and cuboid facet.
The ectal prominence of ETMNH 8054 is relatively larger than in extant taxa studied. In ETMNH
8054, the ectal facet is relatively mediolaterally narrow and ovoid in shape, which is actually fairly
similar to specimens of Brachylagus, and distinct from studied specimens of Sylvilagus and Lepus
where the ectal facet is rather triangular and broad. The cuboid facet of Sylvilagus and Lepus is
more concave (has a smaller radius of curvature) and the cuboid facet of Brachylagus is more
broad than that of ETMNH 8054. As in other leporids, there is a clear calcaneal canal, though
in ETMNH 8054 it has two medial openings adjacent to and proximal to the sustentaculum, and
a single lateral opening adjacent to the lateral surface of the ectal prominence. Interestingly, the
calcaneum from GFS falls within the range of lengths for the specimens of A. vagus described
from Idaho (Table 3), but the element is generally more elongate and slender than the specimens
noted by Campbell (1969).
Remarks—Postcranial remains of leporids from GFS are fairly abundant, including multiple
elements that clearly come from two distinctly different size taxa (Figure 3). The sizes of these
postcranial remains (Table 3) are consistent with observed dental material, with a clearly larger
taxon distinct from the smaller one. The fact that two of the larger specimens, the tibiofibular
(ETMNH 18440) and astragalus (ETMNH 18434) are capable of articulation with one another,
despite originating from different samples at GFS suggests they are from the same taxon. Based
on both size and morphology, we refer larger specimens to cf. Alilepus sp.; the overall size of
these specimens are comparable to larger specimens of Sylvilagus floridanus studied (Table 3).
The morphologies of the bones referred to cf. Alilepus sp. are consistent with the postcrania of
Alilepus vagus described from the Glenns Ferry Formation of Idaho (Campbell, 1969), though,
with the exception of the calcaneum, the GFS specimens are all slightly smaller than those from
Idaho (Table 3). We consider it likely that these specimens are actually from Alilepus vagus, but
the absence of associated cranial and postcranial elements at the site prevents definitive attribution.
There are several interesting features of the referred postcranial specimens that warrant
discussion. The distal humerus (ETMNH 20502) has several features that suggest slightly different
locomotor habits in cf. Alilepus sp. than those of extant leporids like Lepus and Sylvilagus. While
the morphology of this taxon is still clearly consistent with cursoriality, the larger medial epicondyle
of the humerus reflects relatively larger areas of muscle attachment for the wrist and digital flexors
(Reese et al. 2013, Samuels and Van Valkenburgh 2008) and the more shallow groove in the trochlea
indicates less resistance to dislocation of the elbow joint (Hildebrand and Goslow 2001, Winkler et
al. 2016), features that may suggest more terrestrial or burrowing habits. The apparent lesser degree
of cursoriality in A. vagus was previously recognized by Campbell (1969). The presence multiple
of calcaneal canal openings (as is seen in ETMNH 8054) has been noted for extant leporids, but
not in any described fossil taxa (Bleefeld and Bock 2002).
Genus NOTOLAGUS Wilson 1937
Notolagus lepusculus Hibbard 1939
(Figure 4, Tables 1–2, Supp. Tables 1 and 2)
Referred Specimens—ETMNH 20524, right dentary with incisor, unerupted p3, dp4, unerupted p4,
m1; ETMNH 13808, 20520, 20523, 21071, 21072, 21228, 21233, 22422, p3; ETMNH 9693, 9705,
20509, 20602, 20606, lower molariforms (p4–m2); ETMNH 21232, L dp3, dp4; ETMNH 9697, P2;
ETMNH 9696, 12289, 12292, 18429, 20605, 20607, 21226, 21227, 21230, upper molariforms (P3–M2).
Locality—Gray Fossil Site, Washington County, Tennessee.
Age—Early Pliocene (earliest Blancan).
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
14
Description—There are only two dentaries of this taxon from the GFS sample; ETMNH 21233 is
a small jaw fragment with the p3 (Figure 4 E–F) and ETMNH 20524 is a fairly complete specimen
from a relatively young individual, and bears a small incisor, an unerupted p3 with little wear, a
heavily worn and loose dp4, an unerupted p4, and slightly worn m1 (Figure 4 G–H). In ETMNH
20524, the masseteric fossa extends anteriorly to below the trigonid of the m2. In both specimens,
the diastema does not dip strongly anterior to the p3, and bears a relatively gentle curvature. The
incisor is relatively narrow, dorsally flattened, and enamel extends about halfway onto its lateral surface.
All p3 specimens from the GFS sample are distinctly anteroposteriorly elongate and
mediolaterally narrow (Figure 4 A–E). The enamel reentrants of all specimens are cement filled.
In worn p3 specimens (ETMNH 20520, 20523, 21071) the paraflexid (AIR) is deep and curves
distally, the protoflexid (AER) is shallow, the hypoflexid (PER) crosses about half the tooth, and
the mesoflexid (PIR) is absent or shallow. The paraflexid (AIR) is crenulated and its posterior
margin is adjacent the hypoflexid (PER) in nearly all specimens, though it is variably forked. The
Figure 4. Specimens of Notolagus lepusculus from the Gray Fossil Site, Tennessee. A. ETMNH 20520,
R p3; B. ETMNH 21071, L p3; C. ETMNH 20523, R p3; D. ETMNH 21228 L p3, E-F. ETMNH 21233,
L dentary with p3: E, occlusal view; F. lateral view; G-H. ETMNH 20524, L dentary with m1, unerupted
p3 and p4: G, occlusal view; H. lateral view; I. ETMNH 21232, L dp3, dp4; J. ETMNH 9697, R P2.
Scale bars equal 1 mm for A-D and I-J and 2 mm for E-H.
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
15
paraflexid and protoflexid nearly meet in ETMNH 20520, but in other specimens (ETMNH 20523,
21071, 21072) the two flexids are fairly widely separated. In ETMNH 20523 the paraflexid (AIR) is
not crenulated at the occlusal surface, but it is at the base of the tooth. Both the protoflexid (AER)
and hypoflexid (PER) are variably crenulated, with pronounced crenulation evident in ETMNH
20520 and 21071, and subtle crenulation in ETMNH 20523. The mesoflexid (PIR) is absent in
some specimens (ETMNH 20520, 21071), but it changes with wear in others, it is very shallow at
the occlusal surface of the crown and absent from the base of ETMNH 20523.
In the relatively unworn p3 specimens (ETMNH 13808, 21228, 22422) there are distinct
differences between the reentrant pattern on the occlusal surface of the tooth and the tooth base.
On the occlusal surface, the protoflexid (AER) and paraflexid (AIR) meet (in ETMNH 13808) or
nearly meet (ETMNH 21228) in some specimens, which isolates the anteroconid; in the completely
unworn ETMNH 22422 the two reentrants do not meet, as they seem to actually originate slightly
below the apex of the trigonid. The hypoflexid (PER) is deep, crossing more than halfway across
the tooth in all specimens. The mesoflexid (PIR) is shallow (in ETMNH 13808, 20523, 22422) or
absent (ETMNH 21228). At the base of each of these teeth, the paraflexid (AIR) is deep, crenulated
and forked, the protoflexid (AER) is shallow, the hypoflexid (PER) is deep and crosses more than
halfway across the tooth, and the mesoflexid (PIR) is missing and only evident from some cementum
on the posterolingual surface of the tooth.
In addition to the juvenile dentary and eight p3 specimens, five lower molariform teeth are
referred to this taxon. As in the m1 in the dentary of ETMNH 20524, these other referred lower
molariform teeth (p4–m2) lack crenulations. The widths of these teeth are similar to the widths of
the sample of p3 specimens from GFS, as well as m1 of ETMNH 20524.
Two deciduous teeth found associated with one another, a dp3 and dp4 (ETMNH 21232, Figure
4I), are also referred to this species. Though deciduous teeth have not been described for Notolagus
previously, the size and morphology of the dp4 in ETMNH 21232 closely matches that of the worn
dp4 associated with ETMNH 20524, which also includes an unworn p3 that allows identification
of the specimen. The dp3 (ETMNH 21232) has a prominent anteroconid that is separated from
and larger than either the metaconid or protoconid, which are about the same size. The trigonid of
the dp3 is centrally joined to the talonid by a narrow ridge of enamel. The dp4 (ETMNH 21232)
has subtle anteroconid along the anterior margin of the trigonid, a large protoconid, and slightly
smaller metaconid. The trigonid of the dp4 is separated from the talonid at the current level of
wear (no “bridge” of enamel is present).
The only P2 (ETMNH 9697, Figure 4J) in the sample has two anterior reentrants, the lingual
portion (hypercone) is triangular in shape and particularly broad anteroposteriorly, and the labial
portion (lagicone) is rounded and narrower. The paraflexus (MAR) is particularly deep (extends
over half the length of the tooth) and is oriented primarily anteroposteriorly, curving only slightly
laterally. The mesoflexus (EAR) is very shallow. No internal anterior reentrant (IAR) is evident
on the P2, though there is a subtle concavity to the anterointernal surface of the lingual portion of
the tooth. While the paraflexus is cement-filled, the mesoflexus is not, and the rest of the anterior
surface of the tooth completely lacks cementum. In addition to the single P2, nine upper molariform
teeth are referred to this taxon. The widths of these upper teeth are similar to the widths of the
sample of p3 and lower molariform teeth from GFS.
Remarks—The specimens of Notolagus from GFS are referred to N. lepusculus based on
having a p3 with a posteriorly deflected AIR, AIR and AER not merged in any worn specimens,
and variably present PIR (White 1991a). The p3 of N. velox has a relatively laterally oriented AIR,
the AIR and AER are fused in most specimens, and the PIR is absent (Moretti 2018, White 1991a).
It is important to note that the AIR and AER do merge in the unworn crown of ETMNH 13808
and isolate the anteroconid, though the two reentrants are clearly separate at the base of the tooth.
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
16
Another difference of the GFS sample from the diagnosis of N. lepusculus by White (1991a) is that
the P2 (ETMNH 9697) has two anterior reentrants, whereas previously reported P2 specimens of
the species had 3 reentrants.
The GFS sample of Notolagus lepusculus is characterized by considerable variability in
size and p3 morphology (Figure 4 A–E). Overall, the GFS sample (Table 1) is comparable to
and broadly overlaps with the range of p3 sizes for N. lepusculus reported by White (1991a) and
Moretti (2018). The largest and most worn p3 specimens in the GFS sample are over 25% larger
than the smallest worn specimens. The cheek toothrow length of ETMNH 20524 is smaller than in
previously reported specimens of N. lepusculus (Table 2), but this is not surprising given the young
age of this individual and the fact that dental dimensions of lagomorphs can change dramatically
through the course of wear (Bair 2007, Kraatz et al. 2010).
Several morphological features used to distinguish Pronotolagus from Notolagus, like lack of
crenulation on the paraflexid (AIR) and presence of a mesoflexid (PIR), are variably present among
specimens in the GFS sample. White (1991a) actually noted that the PIR was present in two of the
specimens of N. lepusculus he examined. Some of these features are even variable between the
occlusal surface and base of teeth in the GFS sample (ETMNH 13808, 20523). Overall, the teeth
show a pattern of increasing complexity through wear, with: 1) the protoflexid (AER) and hypoflexid
(PER) clearly evident in all individuals, 2) the paraflexid (AIR) highly variable and becoming
deeper, more crenulated, and variably forked through wear, and 3) the mesoflexid (PIR) present in
some specimens, primarily those with lower wear. That variability has important implications for
the taxonomic placement of the genus and for identification of fossil leporid specimens.
Wilson (1937) originally described Notolagus as an archaeolagine based on the fact that the
p3 bore an AIR rather than PIR. Later White (1991a) assigned the genus to the Leporinae because
of the presence of an AIR, an assignment which was followed by Moretti (2018) among others.
However, Dawson (2008) suggested that it be considered a highly derived archaeolagine since
leporines are characterized by possession of a PIR or remnant thereof (Hibbard 1963). Given
the fact the PIR is variably present among specimens the GFS sample, this supports assignment
of the genus to Leporinae, placing it among the most primitive members of the subfamily along
with Pronotolagus (Dawson 2008, White 1991a). The large degree of dental variability observed
here suggests caution should be used when studying isolated specimens of fossil leporids, and
points to risk of incorrect identifications if only small samples are examined. For example, a
specimen like ETMNH 20523 (Figure 4C) could be incorrectly referred to Pronotolagus based
on the reentrant pattern if only its occlusal surface were preserved or examined, which could
easily happen if that tooth were preserved sitting within a dentary or as an isolated tooth with
its base missing.
The P2 referred to Notolagus from GFS (ETMNH 9697, Figure 4J) is clearly distinct from
the other GFS leporid, based on the structure of its anterior reentrants and lack of cementum on its
anterior surface. The size of ETMNH 9697 is also fairly similar in width to the smaller and less
worn p3 specimens of N. lepusculus in the sample (Supplemental Table 1). ETMNH 9697 has two
anterior reentrants, in contrast to the three reentrants noted by White (1991a) in his diagnosis of
N. lepusculus. While there is no internal anterior reentrant (IAR) evident on the P2, the presence
of a subtle concavity to the anterointernal surface of the lingual portion of the tooth suggests it
may have been evident at a lower stage of wear, or variably present. Other species of Notolagus,
namely N. velox, have been described as having only two anterior reentrants (Wilson 1937). White
(1991a) also described N. lepusculus as having “MAR deeper than EAR” and N. velox as having
“MAR slightly deeper than EAR”; in ETMNH 9697 the paraflexus (MAR) is particularly deep
and the mesoflexus (EAR) is very shallow, which resembles N. lepusculus.
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
17
Leporinae Indeterminate
(Figure 3, Table 3)
Referred Specimens—ETMNH 9709, 20497, 20498, 20518, distal humeri; ETMNH 13805, distal
left tibiofibula; ETMNH 22421, left astragalus; ETMNH 9700, 9708, 21229, calcaneum.
Locality—Gray Fossil Site, Washington County, Tennessee.
Age—Early Pliocene (earliest Blancan).
Description—The referred humeri (ETMNH 9709, 20497, 20498, 20518) are all from the left
side and preserve only the distal end of the bone (Figure 3B); the only specimen that includes
more than the distal extremity is ETMNH 20498. Each of the fossil specimens have morphology
similar to studied specimens of Sylvilagus, similar in size to smaller specimens of S. audobonii
and substantially smaller than extant S. floridanus. The distal articulation (trochlea) is like that of
extant leporids studied, with a prominent and deep central groove flanked by a pair of raised splines,
which contrasts with the shallower groove described for the referred specimen of cf. Alilepus sp.
(ETMNH 20502). The epicondyles of the distal humerus are small (HEW/HartW = 1.162 and
1.169), similar in morphology and size to smaller individuals of S. audobonii studied.
The left tibiofibula (ETMNH 13805) only has its distal-most portion preserved; there is no
evidence of an epiphyseal plate, indicating the specimen is from an adult individual (Figure 3H).
Overall, the morphology of the tibia closely resembles that of studied specimens of Sylvilagus,
slightly smaller than S. audobonii and substantially smaller than S. floridanus, and larger than
Brachylagus. The distal articular facets of the tibiofibula are like those of extant leporines studied,
with a distally extended medial astragalar articular facet, deeply depressed lateral astragalar articular
facet, and distally extended calcaneal articular facet. The articular facets are the same width and
capable of articulation with the astragalus to this taxon (ETMNH 22421), but much smaller than
in the astragalus referred to cf. Alilepus sp. (ETMNH 18434). The medial malleolus has a deep
sulcus for the tibialis posterior muscle, and that sulcus extends more proximally on the diaphysis
than in Sylvilagus, Lepus, or Brachylagus. The lateral malleolus is prominent and the sulcus for
the peroneus longus tendon is clear and prominent, but narrower than in Sylvilagus or Lepus, more
similar to that of studied specimens of Brachylagus.
The left astragalus (ETMNH 22421) is complete (Figure 3E, F), and the morphology is similar
to that of extant leporines studied. The overall morphology and size of the bone is similar to that of
Sylvilagus audobonii. As described in the astragalus of cf. Alilepus sp. above, the posterior calcaneal
articular facet is triangular in shape with its apex extending laterally approximately half-way across
the bone, similar to extant leporines. The neck of the astragalus does not show a deep and prominent
constriction, contrasting with archaeolagines like Hypolagus (Campbell 1969, Fostowicz-Frelik
2007). The neck of the astragalus in ETMNH 22421 is relatively long, and the ratio of width of
the astragalus relative to its length for this specimen (AstW/AstL = 0.439) is smaller than in any
of the extant taxa studied (AstW/AstL range from 0.461 to 0.531).
Three calcanea are referred to this taxon, one right (ETMNH 9708) and two left (ETMNH
9700, 21229). The most anterior portions of both ETMNH 9700 and 21229 are missing, thus the
only specimen with a complete cuboid facet is ETMNH 9708. These are similar in morphology
to extant leporines studied, in the range of size of studied specimens of Sylvilagus audobonii,
but smaller than Sylvilagus floridanus. Unlike the calcaneum of cf. Alilepus sp. (ETMNH 8054),
the ectal prominence of these specimens is similar in proportions to that of extant taxa studied,
and the ectal facet is relatively broad and either round or triangular. The cuboid facet of these
specimens has a relatively smaller radius of curvature, like that of Sylvilagus and Lepus. As in
other leporids studied, there is a clear calcaneal canal, with a single medial opening adjacent to
and proximal to the sustentaculum, and a lateral opening adjacent to the lateral surface of the
ectal prominence.
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
18
Remarks—As mentioned above, leporid postcranial remains at GFS are from two distinctly
different size taxa (Figure 3, Table 3), consistent with observed dental material, and have some
differences in aspects of their morphology. The larger specimens, here referred to cf. Alilepus sp.,
are quite similar to previously described material of Alilepus, but there are quite a few smaller
and morphologically distinct specimens from GFS. Those smaller remains are similar in size to S.
audobonii, smaller than S. floridanus and larger than Brachylagus idahoensis (Table 3). It is important
to point out that among those smaller specimens, the tibiofibula, astragalus, and calcaneum described
above all are capable of articulation with one another, despite originating from different samples
at GFS. Consequently, these specimens are considered to be from a single leporine species. The
smaller postcranial remains have a number of morphological features that distinguish them from
the specimens of cf. Alilepus sp. and extant leporines studied (Sylvilagus, Lepus, Brachylagus),
indicating they are from a leporine distinct from any of those taxa. In particular, the lateral and
medial malleolus of the tibia and the neck of the astragalus are distinct from extant and fossil
leporines studied, and the ectal prominence and ectal facet of the calcaneum are distinct from the
described specimen of cf. Alilepus sp.
Based upon their size, abundance, and morphological differences from other studied taxa, the
smaller GFS leporine remains are considered to most likely belong to Notolagus. Since there are no
associated cranial and postcranial specimens yet recovered from GFS, we cannot confidently make
a more precise attribution than Leporinae here. These specimens do represent the first postcranial
remains described as possibly attributed to that genus.
Several aspects of the morphology of the smaller GFS leporine suggest it had a locomotor
ecology similar to relatively cursorial extant members of the family. The prominent splines and
deep groove in the trochlea of the humeri and the relatively small epicondyles indicate the smaller
GFS leporine was relatively cursorial, with an elbow morphology adapted to resist dislocation
and lacking prominent muscle attachments for wrist and digital flexors. Similarly, the relatively
elongate astragalus in the smaller GFS leporine would yield a relatively high velocity ratio for the
muscles responsible for plantar flexion of the foot, which is a morphology characteristic of more
cursorial leporids (Fostowicz-Frelik 2007).
Discussion
The two leporids known from the Gray Fossil Site are well-known taxa with limited stratigraphic
ranges (Supplemental Table 3); Alilepus vagus was previously known to have a broad geographic
range, within the Pacific Northwest (WA and ID), Great Basin (NV), and Great Plains (NB),
and now into the southern Appalachian region. With the specimens described here, the range of
Notolagus lepusculus is also much broader, extending from the Southwest (AZ and NM), to the
Great Plains (KS and TX), and now into Appalachia. These are the first records of both species
east of the Mississippi River. Several extant rabbits in North America have particularly expansive
ranges; for example, the respective ranges of Lepus americanus and Sylvilagus floridanus today
encompass the fossil distributions of A. vagus and N. lepusculus, and more (Bittner and Rongstad
1982, Chapman et al. 1980, Chapman and Ceballos 1990, Murray 2003).
These two taxa are biostratigraphically useful and were recently used to help refine the
interpreted age of the Gray Fossil Site (Samuels et al. 2018), prior records of these species are listed
in Supplemental Table 3. The earliest records of Alilepus vagus are from the Santee Local Fauna of
Nebraska (White 1987), which has recently been discussed as representing the early Pliocene (latest
Hemphillian NALMA), likely between 5.3 and 5.0 Ma (Martin et al. 2017). The most abundant
and well-dated records of this species are from the Hagerman Local Fauna, between 4.18 and 3.11
Ma, from the Glenns Ferry Formation of Idaho (Ruez 2009). The latest records of A. vagus are
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
19
from the early Pleistocene (late Blancan) age Grand View Fauna in Idaho, dating to between 2.6
and 2.1 Ma (White 1987, White and Morgan 1995). All known records of Notolagus lepusculus
are from the Blancan NALMA (Moretti 2018), with the earliest being the early Pliocene age Truth
or Consequences fauna of New Mexico (White 1991a). Most other records of N. lepusculus are
from the late Pliocene, though the record from Roland Springs Ranch in Texas is early Pleistocene
in age (Moretti 2018). Based on the inferred age of the Gray Fossil Site, between 4.9 and 4.5 Ma
(Samuels et al. 2018), the record of N. lepusculus there may be the earliest record of the species.
While both GFS leporids are relatively well-known in the fossil record of North America,
the forest ecosystem preserved at the site is in sharp contrast to that of other sites where they
occur. Floral evidence from the site along with the abundance of arboreal mammals point to the
presence of an oak, hickory, pine forest habitat (Ochoa et al. 2016), likely densely wooded with at
least a partially-closed canopy. Rabbits do commonly occur in such habitats today (Chapman et
al. 1980, Chapman and Ceballos 1990, Murray 2003), but every other site that records these fossil
taxa represent much more open environments, as evidenced by the abundance of large cursorial
mammals. The lack of records of these Neogene rabbits from sites that preserve forest habitats is
at least, in part, a consequence of the biases in the late Cenozoic fossil record of North America,
which is characterized by the presence of many arid sites from the western and central US and
relatively few eastern sites (Bell et al. 2004, Tedford et al. 2004).
It is important to point out that while most of the specimens from GFS described here are
isolated teeth and fragmentary postcranial bones, very few show evidence of pitting or erosion
consistent with digestion by predators. Fragmentation of bones may indicate predation and transport
of specimens (Hockett 1989, 1995; Lloveraas et al. 2008a, b; Schmitt and Juell 1994). However,
the compacted sedimentary deposits in the sinkhole at GFS are also characterized by complete
fragmentation of nearly everything preserved at the site, thus fragmentation of specimens alone
is not good evidence of predation. Only a few of the GFS leporid specimens, like ETMNH 18434
and 20502, show taphonomic modification like pitting and erosion consistent with digestion by
predators (Lloveras et al. 2008a, 2008b; Schmitt and Juell 1994). The majority of leporid specimens
recovered at GFS were likely from individuals that lived in the local area around the site, rather
than having been transported to the site from another area by predators. This suggests the GFS
leporids were actually inhabiting the oak, hickory, pine forest habitat preserved at the site, rather
than some more open habitat farther afield.
As was noted by Dawson (1958), there seem to be two size classes of leporids present at many
fossil sites and in recent faunas. The two rabbits at GFS represent a larger, less abundant Alilepus
and smaller, more abundant Notolagus; this is similar to the co-occurrence of the larger Lepus
and smaller Sylvilagus observed in many modern communities (Dawson 1958). In the southern
Appalachian region today, two different cottontails (Sylvilagus floridanus and S. obscurus) cooccur
with snowshoe hares (Lepus americanus) at higher elevations (Bittner and Rongstad 1982).
Based on their morphological similarity to extant leporines studied, the two GFS leporids likely
filled similar niches in the past.
While the cranial and dental morphology of the two species do not provide any evidence
of apparent niche partitioning, the postcranial morphology of the two taxa preserved at the site
are somewhat different. Despite being limited to a few fragmentary specimens, they can offer
some interesting insights into how these extinct rabbits may have lived. Living lagomorphs vary
substantially in their degree of cursoriality and in some aspects of their limb morphology, with
the limbs of the more cursorially-specialized Lepus generally showing elongation of elements and
reduced mechanical advantage of joints relative to those of the somewhat less-cursorial Sylvilagus
(Young et al. 2014). The smaller rabbit at GFS (possibly Notolagus) displays features that suggest it
was relatively cursorial, including elbow joint morphology characteristic of preventing dislocation
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
20
(Hildebrand and Goslow 2001) and a smaller medial epicondyle of the humerus, along with a
particularly elongate neck of the astragalus. In contrast, the larger cf. Alilepus sp. has an elbow joint
morphology reflecting less specialization for resisting dislocation and larger wrist and digital flexors,
suggesting greater mobility and power at the elbow joint, as is typical of burrowers (Reese et al.
2013, Samuels and Van Valkenburgh 2008, Winkler et al. 2016). This sort of difference in running
adaptation among co-occurring leporids in the Pliocene was also previously observed in rabbits
from the Hagerman Local Fauna (Campbell 1969), and is evident in many modern communities.
Acknowledgements
Specimen collection at the Gray Fossil Site in Tennessee was partially funded through a National Science
Foundation Grant (NSF Grant #0958985) to S.C. Wallace and B.W. Schubert. The remainder of the funding
for the project was provided by internal funding from the Don Sundquist Center of Excellence in Paleontology
at East Tennessee State University. The following curators and collection managers kindly allowed access
to specimens in their care: A. Nye and B. Compton (ETMNH). These specimens were collected through the
important efforts of many volunteers at the Gray Fossil Site, led by S. Haugrud, and some assistance with
preparation of specimens was provided by K. Bredehoeft. Review by two anonymous reviewers and the
suggestions of R. Hulbert substantially improved the quality of this manuscript.
Literature Cited
Armstrong, D.M., J.P. Fitzgerald, and C.A. Meaney. 2010. Desert cottontail. Pp. 264-266, In Mammals of
Colorado (Second Edition). University Press of Colorado. 704 pp.
Ashton, K.G., M.C. Tracy, and A.D. Queiroz. 2000. Is Bergmann’s rule valid for mammals? The American
Naturalist 156(4):390–415.
Averianov, A. 1995. Osteology and adaptations of the early Pliocene rabbit Trischizolagus dumitrescuae
(Lagomorpha: Leporidae). Journal of Vertebrate paleontology 15(2):375–386.
Bair, A. 2007. A model of wear in curved mammal teeth: controls on occlusal morphology and the evolution
of hypsodonty in lagomorphs. Paleobiology 33:53–75.
Bell C.J., E.L. Lundelius Jr., R.W. Graham, A.D. Barnosky, E.H. Lindsay, D.R. Ruez Jr., H.A. Semken Jr.,
S.D. Webb, R.J. Zakrzewski, and M.O. Woodburne. 2004. The Blancan, Irvingtonian, and Rancholabrean
mammal ages. Pp. 232–314, In M.O. Woodburne (Ed.). Late Cretaceous and Cenozoic mammals of
North America; biostratigraphy and geochronology. NY: Columbia University Press. 400 pp.
Bleefeld, A.R., and W.J. Bock. 2002. Unique anatomy of lagomorph calcaneus. Acta Paleontologica Polonica
47(1):181–183.
Bittner, S.L., and O.J. Rongstad. 1982. Snowshoe hares and allies. Pp. 146–163 In J.A. Chapman and G.A.
Feldhammer (Eds.). Wild Mammals of North America. Johns Hopkins University Press, Baltimore,
MD. 1232 pp.
Boardman, G.S., and B.W. Schubert. 2011. First Mio-Pliocene salamander fossil assemblage from the southern
Appalachians. Palaeontologia Electronica 14(2): Article 16A.
Bourque, J.R., and B.W. Schubert. 2015. Fossil musk turtles (Kinosternidae, Sternotherus) from the late Mioceneearly
Pliocene (Hemphillian) of Tennessee and Florida. Journal of Vertebrate Paleontology 35(1):e885441.
Brandon, S. 2013. Discovery of bald cypress fossil leaves at the Gray Fossil Site, Tennessee and their ecological
significance. Undergraduate honors thesis, East Tennessee State University, Johnson City, TN.
Campbell, K.E. Jr. 1969. Comparing postcranial skeletons of Pliocene rabbits. The Michigan Academician
1(1):99–115.
Carrasco, M.A., A.D. Barnosky, B.P. Kraatz, and E.B. Davis. 2007. The Miocene mammal mapping project
(MIOMAP): An online database of Arikareean through Hemphillian fossil mammals. Bulletin of the
Carnegie Museum of Natural History 39:183–188.
Čermák, S., C. Angelone, and M.V. Sinitsa. 2015. New Late Miocene Alilepus (Lagomorpha, Mammalia)
from Eastern Europe–a new light on the evolution of the earliest Old World Leporinae. Bulletin of
Geosciences 90(2):431–451.
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
21
Chapman, J.A., and G. Ceballos. 1990. The cottontails. Pp. 95–110, In J.A. Chapman and J.E.C. Flux (Eds.).
Rabbits, Hares and Pikas: Status Survey and Conservation Action Plan. IUCN/SSC Action Plans for
the Conservation of Biological Diversity. International Union for the Conservation of Nature. 168 pp.
Chapman, J.A., and J.E. Flux. 2007. Introduction to the Lagomorpha. Pp. 1–9, In P.C. Alves, N. Ferrand, and
K. Hackländer (Eds.). Lagomorph Biology: Evolution, Ecology, and Conservation. Springer, Heidelberg,
Germany. 414 pp.
Chapman, J.A., J.G. Hockman, and M.M. Ojeda C. 1980. Sylvilagus floridanus. Mammalian Species 136:1–8.
Crowe, C. 2017. Sciurids (Rodentia: Sciuridae) of the Late Mio-Pliocene Gray Fossil Site and the Late
Miocene Tyner Farm: implications on ecology and expansion of the sciurid record. Masters thesis, East
Tennessee State University, Johnson City, TN.
Dalke, P.D., and P.R. Sime. 1941. Food habits of the eastern and New England cottontails. Journal of Wildlife
Management 5(2): 216-228
Davis, S.J.M. 2019. Rabbits and Bergmann’s rule: how cold was Portugal during the last glaciation? Biological
Journal of the Linnean Society, blz098. https://doi.org/10.1093/biolinnean/blz098
Dawson, M.R. 1958. Later Tertiary Leporidae of North America. Vertebrata Vol. 6. University of Kansas
Paleontological Contributions. Pp. 1–75.
Dawson, M.R. 2008. Lagomorpha. Pp. 293–310, In C.M. Janis, G.F. Gunnell, and M.D. Uhen (Eds.). Evolution
of Tertiary Mammals of North America Small Mammals, Xenarthrans, and Marine Mammals Vol. 2.
Cambridge University Press, New York, NY. 802 pp.
DeSantis, L.R., and S.C. Wallace. 2008. Neogene forests from the Appalachians of Tennessee, USA:
geochemical evidence from fossil mammal teeth. Palaeogeography, Palaeoclimatology, Palaeoecology
266(1):59–68.
Dice, L.R. 1929. The phylogeny of the Leporidae, with description of a new genus. Journal of Mammalogy
10(4): 340-344.
Dice, L.R. 1931. Alilepus, a new name to replace Allolagus Dice, preoccupied, and notes on several species
of fossil hares. Journal of Mammalogy 12:159–60.
Farlow, J.O., J.A. Sunderman, J.J. Havens, A.L. Swinehart, J.A. Holman, R.L. Richards, N.G. Miller, R.A.
Martin, R.M. Hunt Jr., G.W. Storrs, and B.B. Curry. 2001. The Pipe Creek Sinkhole biota, a diverse late
Tertiary continental fossil assemblage from Grant County, Indiana. The American Midland Naturalist
145(2):367–378.
Fortelius, M. 2013. New and Old Worlds Database of Fossil Mammals (NOW). University of Helsinki,
Finland. Available at http://www.helsinki.fi/science/now/.
Fostowicz−Frelik, Ł. 2007. The hind limb skeleton and cursorial adaptations of the Plio−Pleistocene rabbit
Hypolagus beremendensis. Acta Palaeontologica Polonica 52(3):447–476.
Gazin, C.L. 1934. Fossil hares from the Late Pliocene of Southern Idaho. Proceedings of the United States
National Museum 83:111–121.
Gidley, J.W. 1912. The lagomorphs, an independent order. Science 36(922):285–286.
Graham, R.W, and E.L. Lundelius Jr. 2010. FAUNMAP II: New data for north america with a temporal
extension for the Blancan, Irvingtonian and early Rancholabrean. FAUNMAP II Database, version 1.0.
Available at http://www.ucmp.berkeley.edu/faunmap.
Gray, J.E. 1821. On the natural arrangement of vertebrose animals. The London Medical Repository Monthly
Journal and Review 15:296–310.
Hibbard, C.W. 1939. Four new rabbits from the upper Pliocene of Kansas. American Midland Naturalist
21(2):506–513.
Hibbard, C.W. 1963. The origin of the p3 pattern of Sylvilagus, Caprolagus, Oryctolagus, and Lepus. Journal
of Mammalogy 44(1):1–15.
Hibbard, C.W. 1969. The rabbits (Hypolagus and Pratilepus) from the upper Pliocene, Hagerman Local Fauna
of Idaho. Papers Michigan Academy of Sciences Arts and Letters 1(1):81–97.
Hildebrand, M., and G. Goslow. 2001. Analysis of vertebrate structure. Wiley, New York, NY.
Hockett, B.S. 1989. Archaeological significance of rabbit-raptor interactions in southern California. North
American Archaeologist 10(2):123–139.
Hockett, B.S. 1995. Comparison of leporid bones in raptor pellets, raptor nests, and archaeological sites in
the Great Basin. North American Archaeologist 16(3):223–238.
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
22
Hulbert Jr., R.C. 2001. Mammalia 4: Rodents and Lagomorphs. Pp. 226–241, In R.C. Hulbert Jr. (Ed.). The
Fossil Vertebrates of Florida. University Press of Florida, Gainesville. 384 pp.
Hulbert Jr., R.C., S.C. Wallace, W.E. Klippel, and P.W. Parmalee. 2009. Cranial morphology and systematics
of an extraordinary sample of the late Neogene dwarf tapir, Tapirus polkensis (Olsen). Journal of
Paleontology 83(2):238–262.
Jasinski, S.E. 2018. A new slider turtle (Testudines: Emydidae: Deirochelyinae: Trachemys) from the late
Hemphillian (late Miocene/early Pliocene) of eastern Tennessee and the evolution of the deirochelyines.
PeerJ 6 (2018):e4338.
Kraatz, B.P., J. Meng, M. Weksler, and C. Li. 2010. Evolutionary patterns in the dentition of Duplicidentata
(Mammalia) and a novel trend in the molarization of premolars. PLoS ONE 5(9): e12838.
Kraatz, B.P., E. Sherratt, N. Bumacod, and M.J. Wedel. 2015 Ecological correlates to cranial morphology in
Leporids (Mammalia, Lagomorpha). PeerJ 3:e844.
Linnaeus, C. 1758. Systema Naturae per Regna Tria Naturae, Secundum Classes, Ordines, Genera, Species,
cum Characteribus, Differentiis, Synonymis, Locis. Vol. 1: Regnum Animale. Editio Decima, 1758.
Stockholm: Societatis Zoologicae Germanicae.
Lloveras, L., M. Moreno-Garcia, and J. Nadal. 2008a. Taphonomic analysis of leporid remains obtained from
modern Iberian lynx (Lynx pardinus) scats. Journal of Archaeological Science 35(1):1–13.
Lloveras, L., M. Moreno-Garcia, and J. Nadal. 2008b. Taphonomic study of leporid remains accumulated by
the Spanish Imperial Eagle (Aquila adalberti). Geobios 41(1):91–100.
Martin, R.A., P. Peláez-Campomanes, and L. Viriot. 2017. First report of rodents from the late Hemphillian
(late Miocene) Zwiebel Channel and a revised late Neogene biostratigraphy/biochronology of the Sand
Draw area of Nebraska. Historical Biology 2017:1–10.
Mead, J.I., B.W. Schubert, S.C. Wallace, and S.L. Swift. 2012. Helodermatid lizard from the Mio-Pliocene
oak-hickory forest of Tennessee, eastern USA, and a review of monstersaurian osteoderms. Acta
Palaeontologica Polonica 57:111–121.
Meiri, S., and T. Dayan. 2003. On the validity of Bergmann’s rule. Journal of Biogeography 30(3):331–351.
Moretti, J.A. 2018. Early Pleistocene leporids (Mammalia, Lagomorpha) of Roland Springs Ranch Locality
1 and the rise of North American Quaternary leporines. Quaternary International 492:23–39.
Murray, D.L. 2003. Snowshoe hare and other hares: Lepus americanus and allies. Pp. 147–175, In G.A.
Feldhamer, B.C. Thompson, and J.A. Chapman. 2003. Wild mammals of North America: biology,
management, and conservation. JHU Press. 1232 pp.
Nowak, R. 1999. Order Lagomorpha. Pp. 1715–1738, In R Nowak (Ed.). Walker’s Mammals of the World,
Vol. 2, Sixth Edition. Baltimore and London: Johns Hopkins University Press. 2015 pp.
Ochoa, D., M. Whitelaw, Y.S. Liu, and M. Zavada. 2012. Palynology from Neogene sediments at the Gray
Fossil Site, Tennessee, USA: floristic implications. Review of Palaeobotany and Palynology 184:36–48.
Ochoa, D., M.S. Zavada, Y. Liu, and J.O. Farlow. 2016. Floristic implications of two contemporaneous inland
upper Neogene sites in the eastern US: Pipe Creek Sinkhole, Indiana, and the Gray Fossil Site, Tennessee
(USA). Palaeobiodiversity and Palaeoenvironments 96(2):239–254.
Parmalee, P.W., W.E. Klippel, P.A. Meylan, and J.A. Holman. 2002. A late Miocene-early Pliocene population
of Trachemys (Testundines: Emydidae) from east Tennessee. Annals Carnegie Museum 71:233–239
Peers, M.J.L., Y.N. Majchrzak, S.M. Konkolics, R. Boonstra, S. Boutin. 2018. Scavenging by snowshoe hares
(Lepus americanus) in Yukon, Canada. Northwestern Naturalist 99(3): 232-235.
Rasband, W.S. 2007. ImageJ. Bethesda, MD: US National Institutes of Health. Available at http://rsb.info.
nih.gov/ij/, 1997–2007.
Reese, A.T., H.C. Lanier, and E.J. Sargis. 2013. Skeletal indicators of ecological specialization in pika
(Mammalia, Ochotonidae). Journal of Morphology 274(5):585–602.
Ruez Jr, D.R. 2009. Revision of the Blancan (Pliocene) mammals from Hagerman Fossil Beds National
Monument, Idaho. Journal of the Idaho Academy of Science 45(1):1–144.
Samuels, J.X., and S.S.B. Hopkins. 2017. The impacts of Cenozoic climate and habitat changes on small
mammal diversity of North America. Global and Planetary Change 149:36–52.
Samuels, J. X., and B. Van Valkenburgh. 2008. Skeletal indicators of locomotor adaptations in living and
extinct rodents. Journal of Morphology 269:1387–1411.
Samuels, J.X., K.E. Bredehoeft, S.C. Wallace. 2018. A new species of Gulo from the early Pliocene Gray
Fossil Site (Eastern United States); rethinking the evolution of wolverines. PeerJ 6:e4648.
Eastern Paleontologist
J.X. Samuels and J. Schap
2021 No. 8
23
Schmitt, D.N., and K.E. Juell. 1994. Toward the identification of coyote scatological faunal accumulations
in archaeological contexts. Journal of Archaeological Science 21(2):249–262.
Shunk, A.J., S.G. Driese, and G.M. Clark. 2006. Latest Miocene to earliest Pliocene sedimentation and
climate record derived from paleosinkhole fill deposits, Gray Fossil Site, northeastern Tennessee, U.S.A.
Palaeogeography, Palaeoclimatology, and Palaeoecology 231:265–278.
Shunk, A.J., S.G. Driese, and J.A. Dunbar. 2009. Late Tertiary paleoclimatic interpretation from lacustrine
rhythmites in the Gray Fossil Site, northeastern Tennessee, USA. Journal of Paleolimnology 42:11–24.
Tedford, R.H., L.B. Albright III, A.D. Barnosky, I Ferrusquia-Villafranca, R.M. Hunt Jr., J.E. Storer, C.C.
Swisher III, M.R. Voorhies, S.D. Webb, and D.P. Whistler. 2004. Mammalian biochronology of the
Arikareean through Hemphillian intervals (late Oligocene through early Pliocene epochs). Pp. 169–231,
In M.O. Woodburne (Ed.). Late Cretaceous and Cenozoic mammals of North America; biostratigraphy
and geochronology. New York: Columbia University Press. 400 pp.
Trouessart, E.L. 1880. Catalogue des mammifères vivants et fossils; insectivores. Review Magazine Zoologie,
Paris, Series 3 7:219–285.
Wallace, S.C., and X. Wang. 2004. Two new carnivores from an unusual late Tertiary forest biota in eastern
North America. Nature 431:556–559.
Webb, S.D., R.C. Hulbert Jr., G.S. Morgan, and H.F. Evans. 2008. Terrestrial mammals of the Palmetto Fauna
(early Pliocene, latest Hemphillian) from the central Florida phosphate district. Natural History Museum
Los Angeles County Science Series 41:293–312.
White, J.A. 1987. The Archaeolaginae (Mammalia, Lagomorpha) of North America, excluding Archaeolagus
and Panolax. Journal of Vertebrate Paleontology 7:425–450.
White, J.A. 1991a. North American Leporinae (Mammalia: Lagomorpha) from late Miocene (Clarendonian)
to latest Pliocene (Blancan). Journal of Vertebrate Paleontology 11(1):67–89.
White, J.A. 1991b. A new Sylvilagus (Mammalia: Lagomorpha) from the Blancan (Pliocene) and Irvingtonian
(Pleistocene) of Florida. Journal of Vertebrate Paleontology 11(2):243–246.
White, J.A., and N.H. Morgan. 1995. The Leporidae (Mammalia, Lagomorpha) from the Blancan (Pliocene)
Taunton local fauna of Washington. Journal of Vertebrate Paleontology 15(2):366–374.
Wilson, R.W. 1937. A new genus of lagomorph from the Pliocene of Mexico. Bulletin of the Southern California
Academy of Sciences 36:98–114.
Winkler, A.J., L.J. Flynn, and Y. Tomida. 2011. Fossil lagomorphs from the Potwar Plateau, northern Pakistan.
Palaeontologia Electronica 14(3):36A:16p.
Winkler, A.J., D.A. Winkler, and T. Harrison. 2016. Forelimb anatomy of Serengetilagus praecapensis
(Mammalia: Lagomorpha): a Pliocene leporid from Laetoli, Tanzania. Historical Biology 28(1–2):252–263.
Worobiec, E., Y. Liu, and M.S. Zavada. 2013. Palaeoenvironment of late Neogene lacustrine sediments at the
Gray Fossil Site, Tennessee, U.S.A. Annales Societatis Geologorum Poloniae 83:51–63.
Young, J.W., R. Danczak, G.A. Russo, and C.D. Fellmann. 2014. Limb bone morphology, bone strength, and
cursoriality in lagomorphs. Journal of Anatomy 225(4):403–418.
Zobaa, M.K., M.S. Zavada, M. Whitelaw, A.J. Shunk, and F.E. Oboh-Ikuenobe. 2011. Palynology and
palynofacies analyses of the Gray Fossil Site, eastern Tennessee: Their role in understanding the basinfill
history. Palaeogeography, Palaeoclimatology, Palaeoecology 308(3–4):433–444.