BY
E. RAYMOND HALL and WALTER W. DALQUEST
A study of a right maxilla bearing P3-M1 and part of a right
mandibular ramus bearing m2 (see figures) reveals the existence of
an unnamed species of cynarctine carnivore. It may be known as:
Holotype.—Right maxilla bearing P3, P4, and M1, No. 11353 KU; bluff
on west side of Turkey Creek, approximately 75 feet above stream, Raymond
Farr Ranch, Center NE, NE, S. 48 Blk. C-3, E. L. and R. R. Ry. Co.,
Donley County, Texas [approximately 6.5 miles north and 1 mile east of
Clarendon], Clarendon fauna, Early Pliocene age. Obtained by W. W. Dalquest,
on June 25, 1960.
Referred material.—Fragment of right lower mandible bearing m2, No.
11354 KU (see fig. 2), found about two feet horizontally distant from the
holotype in the same stratum as the holotype and on the same date by the
same collector (a staff member of the Department of Biology of Midwestern
University, Wichita Falls, Texas).
Fig. 1. Cynarctus fortidens, No. 11353 KU (Midwestern Univ. No. 2044).
Lateral view of holotype × 1, and occlusal view of check-teeth × 2.
Fig. 2. Cynarctus fortidens, No. 11354 KU (Midwestern Univ. No. 2045).
Lateral view of right lower mandible and m2 × 1 and oblique occlusal view
of m2 × 2.
Diagnosis.—Size large (see measurements); no accessory cusp between
protocone and paracone of fourth upper premolar; first upper molar longer than
broad and lacking cingulum on part of tooth lingual to protocone.
Comparisons.—From Cynarctus crucidens Barbour and Cook (see page 225
of Two New Fossil Dogs of the Genus Cynarctus from Nebraska. Nebraska
Geol. Surv., 4(pt. 15):223-227, 1914; also pages 330 and 338 of Dental
Morphologie of the Procyonidae with a Description of Cynarctoides, Gen.
Nov. Geol. Ser. Field Mus. Nat. Hist., 6:323-339, 10 figs., October 31, 1938)
C. fortidens differs in lacking, instead of having, an accessory cusp between
the protocone and paracone of the fourth upper premolar and in lacking, instead
of having, a cingulum on the part of P4 that is internal (lingual) to the
protocone.
Remarks.—The lower jaw and its second molar seem to be from an individual
significantly larger than the holotype. Possibly the lower jaw and
upper jaw are from two species but the lower jaw probably is from a male
and the upper jaw from a female of the same species.
Reasons for regarding Cynarctus as belonging to the family Canidae instead
of to the family Procyonidae have been stated recently in detail by E. C.
Galbreath (Remarks on Cynarctoides acridens from the Miocene of Colorado.
Trans. Kansas Acad. Sci., 59(3):373-378, 1 fig., October 31, 1956) and need
not be repeated here. Although some uncertainty remains as to the familial
position of Cynarctus, we favor Galbreath's view that the genus belongs in
the family Canidae.
The holotype of Cynarctus crucidens is from Williams Canyon, Brown
County, Nebraska. According to C. B. Schultz (in litt., December 6, 1961),
Williams Canyon is a tributary of Plumb Creek; the upper part of the Valentine
formation and the younger lower part of the Ash Hollow formation are
exposed in Williams Canyon; which one of these formations yielded the holotype
of C. crucidens is unknown.
On the basis of the correlation chart (Pl. 1 in Nomenclature and Correlation
of the North American Continental Tertiary. Bull. Geol. Soc. Amer.,
52(pt. 1):1-48, 1941) by H. E. Wood 2nd et al., C. fortidens and C. crucidens
are equivalent in age or C. fortidens is the younger.
The rounded summits of the principal cusps of the teeth of C. fortidens
suggests that it was mainly frugivorous instead of carnivorous—more frugivorous
by far than the living gray fox, Urocyon cinereoargenteus, that is
known to eat substantial amounts of fruits and berries. Indeed, no other
canid that we know of has teeth so much adapted to a frugivorous diet as
are those of C. fortidens. Its degree of adaptation to a frugivorous diet is
more than in the procyonid genus Nasua but less than in the procyonid genus
Bassaricyon.
Measurements (of crowns) of C. fortidens.—P3-M1, length, 25.8 (millimeters);
P4-M1, 18.9; P3, length, 6.2; P3, breadth, 2.8; P4, length of outer
border, 9.3; P4, breadth, 7.05; M1, length, 9.7; M1, breadth, 9.3; m2, length,
10.3; m2, breadth, 6.6; depth of mandible at posterior end of m2, 17; thickness
of mandible, 7.1.
Transmitted February 21, 1962.
29-2890