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Life Sciences Contributions "IHC 
Royal Ontario Museum I \\J 



Tertiary Mammals 
of Saskatchewan 
Part IV: The Oligocene 
Anthracotheres 



LorisS. Russell 



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Kayser, C. 

1965 Hibernation. In Mayer, W.V. and R.G. Van Gelder, eds. Physiological Mammalogy. 
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LIFE SCIENCES CONTRIBUTIONS 
ROYAL ONTARIO MUSEUM 
NUMBER 115 



LORis S.RUSSELL Tertiary Mammal s 

of Saskatchewan 
Part IV: The Oligocene 
Anthracotheres 



Publication date: 20 March 1978 

ISBN 0-88854-210-0 

ISSN 0384-8159 

Suggested citation: Life Sci. Contr.. R. Ont. Mus. 



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Tertiary Mammals of Saskatchewan 
Part IV: The Oligocene Anthracotheres 



Abstract 

The new species Bothriodon advena is described on the basis of 
the maxillae with both tooth rows, a left maxilla with teeth, and 
an incomplete mandible with most of both tooth rows. These are 
from the Lower Oligocene Cypress Hills Formation of Sas- 
katchewan. The species can be distinguished by dental charac- 
ters from B. rostratus and the various European species, but has 
its closest resemblance to B. velauniis (von Meyer) from the 
Oligocene of Ronzon, France. The two North American species 
clearly belong to Bothriodon, as distinct from Aepinacodon 
Troxell, known from at least two other American species. 



Introduction 

The Anthracotheriidae are a family of "bunoselenodont" artiodactyls known 
from the Late Eocene to Early Miocene of Europe, the Early Oligocene to 
Early Miocene of North America, and the Miocene of Africa and Asia. They 
are distinguished by relatively small, well-spaced anterior teeth, and large, 
close-spaced, more or less rectangular molars. In both upper and lower molars 
the labial cusps are crescentic or V-shaped, whereas the lingual cusps are 
conoid or pyramidoid. The upper molars have a well-developed protonocule 
but no metaconule. The shape of the skull and the spacing of the teeth vaguely 
suggest the camels, but there is nothing cameloid in the limbs, which have four 
short digits, with small, almost pointed ungual phalanges. 

Because of bibliographic confusion in the European literature, North Ameri- 
can students of this family have used a variety of generic names in trying to 
place American species in European genera. The first attempt to introduce 
some order was by Troxell (1929), who noted that the name Bothriodon 
Aymard (1846), contrary to long-standing assumption, had chronological prior- 
ity ovQV Ancodon (Ancodus) Pomel (1847) and Hyopotamiis Owen (1848). The 
last-mentioned name had already been shown by Matthew (1909) to have been 
preoccupied by Kaup in 1844. Troxell cited a number of differences between 
the American species referred to Bothriodon (or Ancodus) and the European 
species of that genus, and proposed that the former be separated in a new 
genu s , A epina codon . 

Troxell's conclusions were accepted in part by Scott (1940), who recognized 
various differences between the European and American species of Both- 
riodon, but concluded that these did not justify separation of the latter as a 
distinct genus, Aepinacodon. However, Macdonald (1956) revived TroxelFs 



genus on essentially the same grounds as that author used, and included A. 
amcncaniis (Leidy), A. dejiectus (Marsh), and A. rostratus (Scott) as the 
constituent species. 

In comparing the American and European species that have been referred to 
Bothriodon or Aepimicodon, I find that the main distinctions are between B. 
amcriccinits and B. deflect us on the one hand, and B. rostratus and the Euro- 
pean B. velaunus (von Meyer), B. leptorhynchus Aymard, ^. ciymardi (Pomel), 
and B. hovinus (Owen) on the other. I would therefore restrict the genus 
Aepincicodon to include A. deflectus (type) and A. americanus, and assign B. 
rostratus to Bothriodon s.s. along with the European species. The new species 
from Saskatchewan, described below, is also referred to Bothriodon s.s. 

The first report of anthracothere remains from Saskatchewan was by Lambe 
(1905), who later described and illustrated the specimens in detail (Lambe, 
1908). These consisted of a well-preserved right M-, a left P\ a right lower 
canine, and two left lower incisors. Lambe referred the molar to Ancodus 
brachyrhynchus (Osborn and Wortman), and the other teeth with question to 
the same species. He also described and illustrated an incomplete tooth which 
he designated as the upper molar of Anthracotheriuml pygmaeum, sp. nov. 
The elongate outline of the crown and the broadly concave lingual margin, as 
well as the small size, make it unlikely that this specimen represents an 
anthracothere, but at present I am unable to offer a more appropriate reference. 

In recent years good anthracothere dentitions have been collected from the 
Cypress Hills Formation (Lower Oligocene) in the valley of Calf Creek, Sas- 
katchewan, and these are the principal subjects of the present contribution. 



Systematic Description 



Order Artiodactyla 

Family Anthracotheriidae Leidv 



Bothriodon Ay mar d 1846 

SYNONYMS. Ancodon {Ancodus) Pomel 1847; Hyopotamus Owen 1848. 

GENERIC DIAGNOSIS 

Anthracotheres of medium size. Snout elongate, concavely attenuate between 

canines and cheek teeth; cheek region expanded laterally. Dentition ' ; 

incisors subequal, bluntly spatulate; canine small to tusk-like, more or less 
compressed, long diastema between C and P'; P' and P-^ trianguloid in side 
view, compressed, with short diastema between; P"* ovoid to trianguloid in 
crown view, with large principal cusp; P'* short, with large labial and smaller 
lingual cusp. Upper molars rectanguloid, with rounded corners, outline wider 
transversely than anteroposteriorly; paracone and metacone high, pointed, 
each with narrow V-shaped crest, the posterior arms of which terminate at the 



labial margin; protocone conoid, with weak crests; hypocone also conoid but 
with V-shaped crest having flattened area between arms; protoconule (unworn) 
as high as protocone, with crest extending anterolabiad; labial margin trilobate, 
with small, pointed parastyle, large mesostyle bulging prominently labiad, and 
small metastyle; little or no external cingulum; moderate anterior and posterior 
cingulum, extending a short distance onto lingual side; deep, almost straight 
transverse valley between protocone, protoconule, and paracone in front, 
hypocone and metacone behind, this valley extending into the mesostyle as a 
broadly rounded or bluntly pointed notch; sides of principal cusps vertically 
striated, especially the protocone. 

Mandible attenuate, but unlike maxillae, the tooth rows are nearly parallel 
for entire length. Canine procumbent in socket but with dorsad-curved crown; 
P, single-rooted, with moderate diastema between it and canine; P2 double- 
rooted, crown trianguloid in side view, relatively long diastema between it and 
?,; P3 similar to P2 but larger, with incipient talonid and strong posterolabial 
cingulum; no diastema between P2 and P3; P4 a little wider than P3, with slightly 
larger talonid; M, with high, conoid metaconid and entoconid, and lower, 
V-shaped protoconid and hypoconid; transverse valley between trigonid and 
talonid opens lingually as well as labially ; M2 similar to M, but a little larger; M3 
similar to M2 but with large hypoconulid spur, which is directed posterolabiad, 
the hypoconulid being similar to, and almost as large as, the hypoconid. 

TYPE SPECIES. Anthracotherium velaunus von Meyer; Oligocene, Ronzon, 
Haute Loire, France. 

DISCUSSION 

The genus Aepinacodon, proposed by Troxell (1921) for the American species 
referred to Bothriodon, is here restricted to ''Bothriodon'' deflectiis (Marsh) 
and ''B'\ americanus (Leidy). The most distinctive feature of /I c^p/Vic/co^o/? as 
compared with Bothriodon is the much shorter anterior portion of the maxillae 
("snout"). From the canines the lateral margins of the palate curve mediad, 
then laterad, without the long, nearly straight portion between the two curves. 
Associated with this feature are the much shorter relative lengths of the C-P^ 
and P^-P- diastemata, although the latter gap is much shorter than the former, 
as in Bothriodon. Differences that have been mentioned in the molar structure 
are the less bulging mesostyle and the posterad curvature of the lingual part of 
the transverse valley. Absence of a diastema between P- and P^ has been 
suggested as a distinctive character, but it is also absent in some European 
species of Bothriodon. Other characteristics listed as distinctive by Troxell and 
Macdonald should be checked against the European material. 

Bothriodon advena, n. sp. 
Figs. 1-4 

ETYMOLOGY. Latin advena, immigrant or foreigner. 

TYPES. Holotype, Royal Ontario Museum, Department of Vertebrate Palaeon- 



tology (ROM) 2 1744, skull fragment mostly consisting of the maxillae, with left C 
to M^ and right P^ and P"^ to M\ Paratype, rom 21745, incomplete mandible 
with left Pi toP4, M.and M3, and right P2toP4, M2and M3, and alveoli for three 
incisors and a canine on each side and for right P,; probably from same 
individual as rom 21744; Saskatchewan Museum of Natural History (smnh) 
P 1063. 1 , incomplete left maxilla with P' to M"* and trace of alveolus for canine. 

PROVENIENCE. Cyprcss Hills Formation, Lower Oligocene. Calf Creek valley, 
sees. 7 and 8, tp. 8, rge. 22, W. 3rd merid., Saskatchewan. 

SPECIFIC DIAGNOSIS 

Upper canines moderately large for the genus. P^ present; P- simple, without 
posterior cusp; P*^ without lingual cingulum; transverse valley of upper molars 
terminating labially as a pointed end on M' and M-, as a rounded U-shape on 
M^; posterior cingulum near midwidth on M\ In lower dentition, P3 and P4 are 
widest posteriorly, the latter tooth having an incipient talonid; M3 with 
hypoconulid almost as high as hypoconid. 

DESCRIPTION 

The holotype of the species (rom 21744) consists almost entirely of the two 
maxillae. Anteriorly there may be a small fragment of the left premaxilla, and 
posteriorly the anterior portion of the palatines extends in the median area as 
far forward as the anterior margin of M\ The dorsal side of the specimen is 
shattered and encrusted, but further preparation might lead to collapse. The 
roof of the nares is visible posteriorly, as is the anterior floor of the orbital 
cavities. The anterior portion of the maxillae is bent downward between P' and 
P-, but this is evidently a post-mortem distortion. Seen in ventral view the most 
striking feature is the contrast between the narrow, elongate anterior portion of 
the maxillae and the abrupt lateral expansion from P"* posterad. This is em- 
phasized by the small and well-spaced teeth from incisors to P^ and the 
relatively massive and close-spaced teeth from P^ to M\ The spoon-like 
expansion of the premaxillae and anterior part of the maxillae, characteristic of 
the genus, is obscured in this specimen by breakage and distortion. 

None of the six incisors is represented, not even by portions of the alveoli. 
The left canine is prominent but not tusk-like. It emerges from its alveolus at a 
low angle, then curves forward, outward, and downward. The crown makes up 
about half of the tooth presently exposed. It is pointed, recurved, and laterally 
compressed, with no serrations on either edge. 

There is a long diastema between the canine and the first premolar. The latter 
tooth is small, with a low, compressed, trianguloid crown, from the apex of 
which a blunt, nonserrate edge extends fore and aft. The two roots are swollen, 
and divergent dorsally. 

Between P' and P- there is a moderately long diastema, less than half the 
length of that between C and P'. P- is like P' but larger, and with a less 
compressed crown. The apex is slightly in front of midlength, and a strong but 
worn ridge extends from it posterodorsad to the posterior margin. Anterior to 
the apex there are two low ridges, diverging anterodorsad. External and inter- 
nal cingula are present, weak anteriorly, strong and denticulate posteriorly. 




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P^ is a much larger tooth , trianguloid in crown view, the posterolabial portion 
bulging labiad in conformity with the changing orientation of the maxillary 
margin. The apex of the tooth is slightly in front of midlength. From this a ridge 
extends anterodorsad to the anterolingual angle of the crown. There is an 
elongate wear facet on the anterior slope of the crown but this is in the midline 
of the tooth and does not obliterate any of the anterolingual ridge. On the 
posterior side of the apex there is a strong ridge extending posterolabiad to join 
with a distinct cusp (''tritocone'') and continue to the posterolabial angle of the 
crown. The posterior face of the crown is a broad, flat wear facet, which has 
been formed by the destruction of most of the posterior cingulum, but leaving 
part of the enamel surface. There is a weak, striate, external cingulum, and a 
denticulate internal cingulum. 

P"* is a very different tooth, ovoid in outline, distinctly wider than long, and 
resembling the anterior half of the first molar. The crown consists of two cusps, 
an outer, principal cusp (paracone analogue) with a V-shaped crest, and a 
somewhat smaller and conoid inner cusp (''deuterocone''). The labial margin 
of the crown is slightly sinuous, with distinct anterior and posterior angles, but 
the lingual margin is rounded. The cingulum is vestigial on the labial margin, 
weak anteriorly and posteriorly, and absent from the lingual margin. 

M' was evidently a slightly smaller version of M-, but it has been heavily 
worn. The protocone-paracone-metacone area has been reduced to a large, 
horizontal facet, while the hypocone, metacone, and posterior margin have 
been entirely removed, leaving a slightly concave facet that slopes posterad. 
The only diagnostic feature preserved is the labial end of the transverse valley, 
which is a pointed re-entrant on the lingual side of the mesostyle. 

M- is somewhat larger than M^ It is rectanguloid in crown view, except for 
the metastyle angle, which protrudes posterad. Wear has reduced the pro- 
tocone and protoconule to a large, triangular facet. The hypocone, although 
worn, still retains its V-shaped crest. Paracone and metacone also have their 
V-shaped crests partially preserved. The mesostyle, although worn, preserves 
the pointed end of the transverse valley. The anterior and posterior cingula 
have been mostly removed by wear. 

M^ is slightly larger than M-, and is only moderately worn. The pyramidoid 
protocone is still pointed, but the protonule shows some wear. The postero- 
lingual slope of the protocone is radially ribbed. The V-shaped crest of the 
hypocone is worn anteriorly, intact posteriorly. The V-shaped crests of the 
paracone and metacone are variously worn, the posterior arm in each case 
being more truncated than the anterior. The transverse valley has numerous 
cross-crenulations; it terminates on the lingual side of the mesostyle as a 
broadly rounded notch. The labial and lingual cingula are vestigial. There is a 
strong anterior cingulum from the parastyle to a point anterior to the protocone 
apex. The posterior cingulum is confined between points posterior to the apices 
of the metacone and hypocone, respectively. 

The paratype maxilla (smnh P1063. 1) has almost unworn teeth, but unfortu- 
nately only the left P' to M^ are present. Compared with the holotype, and 
allowing for the excessive wear of the latter, the differences are of minor 
degree. The rim of the canine alveolus is not preserved, but about 50 mm of the 
C to P' diastema remains. 

10 



P^ P^, and P"^ are almost identical in the two specimens. P^, which is unworn 
posteriorly on the paratype, shows a strong posterior and lingual cingulum. On 
P^ the lingual cusp ("deuterocone") is a little more anteriorly placed than on 
the holotype; there is a distinct ridge extending anterolabiad from the apex of 
this cusp to the anterior cingulum. The labial margin of the crown is shallowly 
concave. 

M' is the only worn tooth on the paratype. Protocone and protoconule have 
been reduced to a concave facet. The hypocone, paracone, and metacone 
retain most of their V-shaped crests. The mesostyle bulges broadly, and the 
labial end of the transverse valley is bluntly pointed. There are distinct but 
narrow anterior and posterior cingula, and vestiges of an internal cingulum. 

M^ is the best-preserved tooth on the paratype. All of the cusps retain a 
pointed apex, although the protocone shows incipient wear. The posterior 
slope of the protocone has numerous distinct radiating ridges. The transverse 
valley ends labially in the mesostyle as a more narrowly pointed notch than on 

M^ shows no signs of wear, but the posterior third of the crown has been 
fractured and slightly spread. The protoconule is higher than the protocone. 
The mesostyle is large, and the labial end of the transverse valley is U-shaped, 
rather than rounded or pointed. The anterior cingulum is wide adjacent to 
protocone and protoconule; the posterior cingulum is restricted. 

The paratype mandible (rom 21745), as noted, could be from the same 
individual as the holotype. This is suggested not only by the common proveni- 
ence but also by the analogous state of wear of the teeth. The anterior end of the 
mandible is narrowly rounded, and the symphysis is long and shallowly 
trough-shaped. For the entire length as preserved the two rami are almost 
parallel, gradually becoming more massive posteriorly, but showing nothing 
like the abrupt divergence of the maxillary margins. 

The incisors and canines are represented by their alveoli, which are directed 
more anterad than dorsad. P, is represented on the left side by the single root, 
the crown having been worn away. The diastema between C and P, is relatively 
short. In contrast, the diastema between P, and P2 is almost twice as long. The 
dorsal rim of the rami in the P1-P2 diastema is an acute edge. 

P2 has a compressed crown, trianguloid in side view, with a single cusp and a 
posterolingual denticle. The ridges from the principal cusp have a convex slope 
in front, concave behind, giving the tooth a slightly recurved appearance in side 
view. The two roots are large and divergent, but not swollen. 

P3 is similar to P2 but larger. The rudimentary talonid is worn. There is a 
distinct lingual cingulum, which rises up the side of the crown just behind the 
apex. 

P4 is badly worn, but evidently had a high principal cusp and a distinct 
talonid. In crown view the outline tapers obliquely in front of the principal cusp 
but is broadly rounded behind. There is a strong lingual cingulum. 

M, is missing on both sides. Judging from the extreme wear of M2, the MM, 
must have been reduced to their roots during life, and may have been dis- 
carded. M2 is very badly worn, the protoconid being completely removed, and 
the metacone reduced to a remnant. The talonid on the left M2 is as worn as the 
trigonid, but on the right M2 there is a large remnant of the hypoconid. 

// 



M3 is moderately worn, there being curious discrepancies between this tooth 
on the right ramus and that on the left. Thus the metaconid is high and pointed 
on the right, truncated on the left. In contrast, the entoconid is less worn on the 
left than on the right. Protoconid and hypoconid have oblique V-shaped crests, 
whereas metaconid and entoconid are conoid. The hypoconulid lobe is well 
developed, curving posterolabiad. It is only slightly worn, the posterior trunca- 
tion on the right M3 being a post-mortem break, not a wear facet. 



DIMENSIONS 

Vertical 

Holotype, rom 21744 

Left canine 15.2 mm 

Diastema, C to P' 

Maxillae between dentigerous margins at PP' 

Left P' at base of crown 

Diastema, P' to P- 

Left P-, at base of crown 

Left P^ 

Left P'* 

LeftM' 

Left M- 

Left M^ 

Maxillae and palatines between dentigerous mar- 
gins at MM^ 



t-post. Tf 


•ansverse 


10.9mm 


7.9 mm 


67.7 






36.0 


8.5 


4.8 


21.0 




14.0 


7.8 


17.8 


17.3 


17.3 


20.5 


21.4 


24.9 


28.3 


31.0 


30.8 


31.4 



113 



Paratype, smnh P1063.1 

Diastema, left C to P'. . . 

LeftP' 

Diastema, left P' to P- . 
Left P^ at base of crown 
LeftP^ 



Left P"* 
LeftM' 

Left M- 
LeftM^ 



+ 53 
8.7 

±19 
16.2 
18.6 
15.6 
22.3 
29.3 

±30 



5.1 

8.5 
17.6 
20.1 
24.3 
30.9 
33.3 



Paratype, rom 2 1745 

Mandibular symphysis 94. 1 

Diastema, left C and Pi 25.3 

Left Pi , as preserved 8.5 

Diastema, left Pi to P2 46.5 

Right P2, at base of crown 12.1 

Right P3, at base of crown 19.2 

Right P4 19.6 

Right M2 22.5 

Right M3 38.0 



5.5 

6.1 

8.9 

12.8 

18.0 

19.4 



12 



DISCUSSION 

The anthracothere dentition usually shows much difference in the degree of 
wear between teeth of the same series, but in the holotype maxillae and the 
paratype mandible of this species the condition reaches an extreme, not 
equalled by the paratype maxilla. This suggests either an unusually harsh diet 
or an exaggerated time interval between the eruption of successive teeth. Thus 
the first molar, both above and below, appears to have had the crown almost 
completely obliterated before the last molar and the fourth premolar were 
entirely functional. 

The nature of the wear facets is also noteworthy. Most of these facets on the 
upper cheek teeth have a nearly horizontal transverse axis with a posterad or 
anterad slope. This suggests that most of the jaw motion in chewing was 
transverse. We can visualize the animal stripping, rather than cropping, vegeta- 
tion with its well-spaced but weak anterior teeth, then working it back to the 
wide cheek region for comminution by side-to-side motion of the lower denti- 
tion against the upper. Such movement would have to be wide because of the 
much greater lateral distance between the tooth rows on the maxillae and those 
on the mandible. In this motion the anterior portion of the mandible would have 
to swing widely on the pivot of the glenoid cavities, but as the anterior teeth 
were not interlocking, this motion was evidently no problem. The general 
effect would be an exaggerated "chewing-the-cud'' motion comparable to that 
of ruminants. 

The well-preserved right M^ referred by Lambe (1908, p. 24) to Ancodus 
{Hyopotamus) brachyrhynchus Osborn and Wortman is of about the same size 
as that tooth in Bothriodon advena. There are, however, a number of differ- 
ences. The V-shaped crests on paracone and metacone are less acutely angu- 
late on Lambe's specimen, and there is a posterolabial crest from the pro- 
tocone. The transverse valley is more shallow, and its labial half is deflected a 
little posterad, instead of being directed strictly labiad. In these features the 
tooth closely resembles a left M^ (rom 973) identified as Elomeryx annatus 
(Marsh), from the Brule Formation of South Dakota. It was obtained in ex- 
change from the American Museum of Natural History. As Ancodus 
brachyrhynchus is now regarded as a synonym of Elomeryx armatus (Mac- 
donald, 1956), Lambe's identification was very good and cannot be improved 
upon in spite of the greater geological age of the Cypress Hills specimen. 

Lambe also referred, with question, to Ancodus brachyrhynchus a left P"^ 
that is very unlike the P"^ of Bothriodon advena. In addition to being smaller, 
Lambe's specimen has a broad, shallowly concave shelf projecting posterolin- 
guad, in place of a simple cingulum. Lambe also described two lower incisors 
and a lower canine, but as these teeth are missing from the type material of ^. 
advena, no comparisons can be made at present. 

Comparison of the dentition oi Bothriodon advena with that of other species 
definitely belonging to that genus shows only minor differences. The other 
North American species, B. rostratus (Scott), differs most conspicuously in the 
absence of P'. Macdonald (1956, p. 622) suggested that this might be only an 
individual variation, but Scott (1940, p. 465) noted that this tooth was com- 
pletely unrepresented in both the specimens that he studied. The handsome 

13 



skull of B. rostratus in the Princeton University Museum that was figured by 
Scott (op.cit., pi. 46) has a spoon-like outline of the anterior palate, a feature 
seemingly less developed in B. aclvcna. Another difference is the presence of a 
complete internal cingulum on P^ in B. rostratus. In that species the transverse 
valleys of all of the upper molars, not just M\ have a rounded labial end. 

Turning to the European species of Bothriodon, we find that the nomencla- 
ture and the specific identities are as confused as those for the genera. The first 
species to be recognized was "'Anthracotherium'^ veUiunus. This is usually 
credited to Cuvier, but he (1835) referred to it only in the vernacular, ''An- 
thracotheriums du Puy en Velay'\ Apparently von Meyer ( 1832) was the first to 
use a formal binomial for the species, translating Cuvier's name into An- 
thrcicotherium veUiuniim. Following this, various authors such as Aymard 
( 1846), Pomel ( 1847), and Owen (1848) added species, until Filhol (1882), using 
PomeFs generic name revised to Ancodiis, recognized four species: Ancodus 
velauiuis Pomel [sic], A. leptorhynchus (Aymard), A. hovinus (Owen), and 
A. porcinus Pomel. In 1885 Lydekker recognized a somewhat different set of 
species: Hyopotamiis velauniis (Cuvier) (including H. vectianus Owen), H. 
boviniis Owen, //. porcinus (Gervais), H. americanus (Leidy), H. picteti 
Lydekker, and H. giganteus Lydekker. He followed Filhol in assigning An- 
codus aymardi Pomel to A. leptorhynchus, and in turn synonymized A. lep- 
torhynchus with Hyopotcunus hovinus. 

Without access to European collections and to all of the literature I shall not 
attempt a critical review of the species of Bothriodon, but for comparison with 
the Cypress Hills species I shall recognize four species as distinct: B. velaunus 
(von Meyer), B. leptorhynchus Aymard, B. hovinus (Owen), B. vectianus 
(Owen). B. velaunus, on the basis of the skull described by Filhol, has the 
greatest resemblance to B. advena. Thus the canine appears to be moderately 
large, and close to the P. The diastema between C and P' is a little more than 
three times in length that between P' and P'. P^ is trianguloid, and P'* has a 
distinct lingual cusp. Differences to be noted are the absence of a posterolabial 
projection of P\ the relatively narrower P"^ (in B. advena this tooth is almost as 
wide as M'), and the broadly rounded or inflated labial ends of the transverse 
valley of the molars. The dental dimensions of ^. velaunus are about three- 
quarters those of ^. advena. 

The skull described by Filhol as Ancodus leptorhynchus has dimensions 
similar to those of Bothriodon advena but there are striking differences. The 
canine is large and recurved in suid fashion, and is well separated from V. The 
snout is extremely elongate, the distance from C to P-^ exceeding the length of 
P^ to M\ The diastema between P' and P' is relatively long, being about -/s that 
of the C-P' diastema compared to ^/-j in B. advena. In B. leptorhynchus the P^ is 
ovoid rather than trianguloid, and P'* is about as long as wide, with rudimentary 
lingual cusp but a distinct internal cingulum. The transverse valley of the 
molars is expanded at the labial end, especially on M^. 

B. aymardi was regarded by Filhol, with reservations, as the female of ^. 
leptorhynchus. In view of other differences in addition to smaller size and 
reduced canine, it seems better for purposes of comparison with B. advena to 
regard the two Ronzon species as distinct. In size, according to Filhol, B. 
aymard is about 0.6 that of ^. leptorhynchus and about 0.7 that of ^. velaunus. 

14 



On the basis of Filhol's plate 16, the dental dimensions ofB. aymardi are about 
two-thirds those ofB. advena. On B. aymardi there is a short diastema between 
P^ and P^, and the latter tooth is rounded-trianguloid, with no posterolabial 
projection. P'* is short and wide, as in B. advena, but the lingual cusp is less 
prominent. The labial ends of the transverse valleys of the molars are rounded 
but not inflated. 

Comparisons with Owen's species from the Isle of Wight are difficult, as the 
specimens on which they are based consist mostly of isolated teeth. Owen 
assembled some of these in supposed tooth rows, but as Lydekker pointed out, 
the associations are faulty. On the basis of the upper dentition, especially the 
dimensions, Lydekker referred ''Hyopotamus'' leptorynchus to "//." 
boviniis. As noted, Aymard's name has priority over Owen's. However, 
Bothhodon boviniis has a wide P^ with large lingual cusp, as in ^. advena, and 
the transverse valleys on the upper molars are broadly rounded but not inflated 
at the labial end. I think that Bothriodon leptorhynchiis and B. boviniis should 
be retained as distinct species until the discovery of associated tooth rows of 
the EngUsh species, when the question of their validity might be reconsidered. 

In summary, Bothhodon advena, 2i\ong with B. rostratiis (Scott), is a charac- 
teristic member of the genus Bothriodon, as distinct from Aepinacodon 
Troxell. The new species differs from the European members of Bothriodon in 
various minor details. Closest resemblances are to B. velaiinus, to which it 
would probably be referred if found in Europe. It is generally agreed that the 
anthracotheres originated in Eurasia and made their way into North America in 
Oligocene time. As the oldest-known American species geologically, and the 
closest geographically to the Bering connection, Bothriodon advena may be 
regarded as a relatively unmodified member of the immigrant stock, hence the 
choice of specific name. 



Acknowledgements 

Loan of anthracothere specimens in the vertebrate palaeontology collection of 
the National Museum of Natural Sciences, Ottawa, was arranged by Dr. D. A. 
Russell . The left maxilla described above as the paratype oi Bothriodon advena 
was lent by the Saskatchewan Museum of Natural History, courtesy of Dr. 
John E. Storer, Assistant Director. Loan of the rare volume cited under Filhol 
(1882) was arranged by Dr. Robert E. Carroll from the McGill University 
Library. Specimens and facilities in the Department of Vertebrate Palaeontol- 
ogy, Royal Ontario Museum, were provided by Dr. A. G. Edmund, Curator. 



15 



Literature Cited 



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1846 Essai monographique sur un nouveau genre de mammifere fossile trouve dans la 
Haute-Loire, et nomme Entclodon. Annales de la Societe d'agriculture, sciences, arts 
et commerce du Piiy. 12 (1842-46): 227-267, 1 pi. 

CUVIER, GEORGES 

1835 Recherches sur les ossemens fossiles, ou Ton retablit les caracteres de plusieurs 
animaux dont les revolutions du globe ont detruit les especes. Paris, Edmond 
d'Ocagne; 4th ed. , 5(3): 480, 48 1 . 

FILHOL, HENRI 

1882 Etude des mammiferes fossiles de Ronzon (Haut-Loire). Annales des sciences 
geologiques, Paris, 12(3): 1-271, 26 pis. 

LAMBE, L. M. 

1905 Vertebrate palaeontology. Geological Survey of Canada, Summary report of the opera- 
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1908 The Vertebrata of the Oligocene of the Cypress Hills, Saskatchewan. Geological 
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LYDEKKER. RICHARD 

1885 Catalogue of the fossil Mammalia in the British Museum (Natural History) Part II. 
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MACDONALD. J. R. 

1956 The North American anthracotheres. Journal of Paleontology, 30(3): 615-645, 16 figs. 

MATTHEW, W. D. 

1909 Observations on the genus Ancodus. Bulletin of the American Museum of Natural 
History, 26(1): 1-7. 

MEYER, H. VON 

1832 Palaeologica, zur Geschichte der Erde und ihrer Geschopfe. Frankfurt a.M., 560 pp. 

OWEN, RICHARD 

1848 Descriptions of teeth and portions of jaws of two extinct anthracotherioid quadrupeds 
(Hyopotamiis vectianns and Hyop. hoviniis) discovered by the Marchioness of Hast- 
ings in the Eocene deposits on the N.W. coast of the Isle of Wight: with an attempt to 
develop Cuvier's idea of the classification of pachyderms by the number of their toes. 
Quarterly Journal of the Geological Society of London, 4(1): 103- 141, 2 pis. 

POMEL, AUGUSTE 

1847 Note critique sur les caracteres et les limites du genre PaUwothcntiin. Archives des 
sciences physiques et naturelles, Geneva, 5: 200-207. 

SCOT I , W. B. 

1940 Artiodactyla. Part IV in Scott, W. B., and G. L. Jepsen, The mammalian fauna of the 
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IROXLLL, h. L. 

1921 The American bothriodonts. American Journal of Science, 201(21): 325-339, 7 figs. 



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