A Pliocene fauna from Western Nebraska / by W.D. Matthew and Harold J. Cook.

  • Matthew, William Diller, 1871-1930.
Date:
1909
Catalogue details

Licence: In copyright

Credit: A Pliocene fauna from Western Nebraska / by W.D. Matthew and Harold J. Cook. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    1009.] tubercular dentition into a transverse blade. Corresponding divergence in adaptation may be seen in the .Eluroid group between the Yiverrine and Feline extremes, also traceable back (structurally) to the Miacid type of dentition. Measurements of T. hippopahgus. Type, No. 13836. mm. Lower jaw, canine to condyle inclusive Lower dentition c-m3 . “ premolars, pi_j ... “ true molars, mi-s . 11S. 79. 33. 35.8 p2, anteroposterior 8.5; transverse p» it 9.4 p4 if 12. M, ft 19.7 M, 11 10.3 o. 6. 6.S 9. Depth of jaw beneath m2 . It it it fi n Fs • Height from angle to tip of coronoid process 25.2 21.3 56. No. 13834 Upper molars m1'2, anteroposterior M1, anteroposterior, along line of outer cusps “ transverse, across metacone .... “ oblique across paracone M„ “ “ 12.; anteroposterior 21. 14.2 15.8 18. 8. We are disposed to regard Tephrocyon as approximately ancestral to Canis on the one hand and .Flu rod on on the other, and to refer to it a num- ber of the later Tertiary dogs which have been heretofore placed in the modem genus Canis. They retain a number of primitive features, most of which are also retained by JElurodem, but they differ from that genus in the absence or rudimentary development of the anteroexternal cusp or parastvJe (protostyle of Scott’s nomenclature) of the upper camassial, in the less re- duction of the premolars and in other more generalized features. The skull is known only in the type species, which, as Merriam observes, may be approximately ancestral to JElurodon. The species from the Upper Miocene and Pliocene are somewhat nearer to Canis, but the direct ancestors of the modern species of wolves, jackals and true foxes will more probably be found in the Pliocene and Pleistocene of Northern Asia and Arctic America. Some of the smaller species of Tephrocyon from the' later Tertiary of North America may however be direct ancestors of the modern dog-foxes of South and Central America.