EVOLUTION OF THE SKELETON OF EOCENE AND OLIGOCENE TITANOTHERES 



653 



SUBFAMILY TEEMATHEEIINAE 



Telinathedum ultimum (referred) 



The hind limb of Telmatherium ultimum (Am. Miis. 

 1942), from Uinta C, indudes the femur, tibia, and 

 pes. It is evidently of palaeosyopine rather than 

 manteoceratine affinity. Its association with the 

 genus Telmatherium of the palaeo- 

 syopine group is provisional and 

 rests mainly on the characters of 

 the femur, tibia, and pes, especially 

 on the short neck and facets of 

 the astragalus, which are of the 

 palaeosyopine rather than of the 

 manteoceratine type. The tibio- 

 femoral ratio is 70. 



The entire length of the hind 

 limb from the head of the femur 

 to the extremity of Mts III is 

 estimated at 965 millimeters, 

 distributed as follows: Femur, 

 crushed, estimated, 400; tibia, 

 actual length, 323 ; pes, estimated, 

 240. 



The femur exhibits a very prom- 

 inent third trochanter, which is 

 considerably lower down on the 

 shaft than the second trochanter. 

 The palaeosyopine character is 

 seen especially in the broad patellar 

 facet, which is elongate and faces 

 anteriorly. The tibia presents a 

 slight anterior depression in the 

 cnemial crest. 



The pes (fig. 593) is more dis- 

 tinctive. It is of an advanced 

 type in many details; its refer- 

 ence to Telmatherium rather than 

 to any of the Manteoceratinae is 



Figure 592. Hind ^ue to the character of the astrag- 



limb referred to Te?- alus, which is of the short-necked 

 matherium tilHvium type, with a broad oval susten- 

 Am. Mus. 1942; Uinta c. tacular facet; the very large tibio- 

 one-sixth natural size. ^stragalar trochlea is broad and 

 flat, presenting anteriorly; the navicular facet spreads 

 well on the front face of the astragalus; the cuboidal 

 facet is narrower than in Protitanotherium. The navic- 

 ular and ectocuneiform are also low and broad 

 elements of graviportal type. 



All these bones are deep anteroposteriorly, and all 

 facets are subhorizontal or subvertical rather than 

 oblique. The metatarsals are likewise broad and in 

 detailed characters suggest those of the Bridger 

 Palaeosyopinae on a larger scale. The proximal 

 facets of the metatarsals are deeply extended antero- 

 posteriorly, as in the Palaeosyopinae, and unlike those 

 of Dolichorhinus, which are shallow, as in the Manteo- 

 ceratinae. 



Skeletal remains originally referred to Diplacodon elatus by 

 Scott and Osborn 



In 1890 parts of four separate skeletons from Uinta 

 C 1 (Princeton Mus. 10393, 10395, 10396, 10396a) 

 were described by Scott and Osborn (1890.1) and were 

 all attributed to Diplacodon elatus. It has been dem- 

 onstrated in Chapter V that Marsh's type of D. elatus 

 shows affinities to both Menodus and Brontofherium. 

 The elongate proportions of the skeletons now to be 

 described, moreover, resemble those of the Oligocene 

 Menodus rather than those of the Oligocene Brontops; 

 consequently it appears improbable that they belong 

 to Protitanotherium, which in cranial characters resem- 

 bles Brontops. The generic and specific references are 

 therefore uncertain. 



The principal characters are as follows: (1) Short 

 neck, cervical vertebrae flattened and abbreviated; (2) 

 long limbs, pelvis and feet elongated as in Menodus; (3) 

 prominent and recurved hook on the humerus; (4) meta- 

 podials of manus elongated, stilted, functionally tetra- 

 dactyl in proportion; (5) radius long and slender (Am. 

 Mus. 2035); (6) tibiashort and massive(Am. Mus. 2056). 



Cervicals. — It is noteworthy that the cervical centra, 

 although belonging to an animal nearly double the size 

 of Palaeosyops in height and breadth, are only a trifle 

 longer, a fact which points to the 

 progressive abbreviation of the 

 neck. The axis (Princeton Mus. 

 10396a) exhibits a broad spine 

 overhanging the postzygapoph- 

 yses, laminae very slightly 

 notched, postzygapophyses of 

 elongate oval form, transverse 

 processes hooked and perfo- 

 rated at the base, centrum with 

 a sharp inferior keel. The re- 

 maining cervicals and dorsals 

 (Princeton Mus. 10396) prob- 

 ably belong to a single indi- 

 vidual. The cervicals are prob- 

 ably the third, fourth, fifth, and 

 sixth. Of these C. 5 is the most 

 complete, spine pointed, verti- 

 cally placed and grooved pos- 

 teriorly, zygapophyses very 

 stout, facets placed at angles 

 of 45°, vertical diameter of 

 the centra much greater than 

 the transverse, opisthocoelous, 

 transverse processes not ex- 

 tending below the level of the centrum. The centra 

 of seven dorsals are preserved. Figure 594 repre- 

 sents one between the seventh and tenth exhibiting 

 the following characters: Centrum opisthocoelous 

 and considerably excavated at the sides; anterior, 

 posterior, and transverse diameters about the same; 

 lower half of the spine triangular, indicating a con- 

 siderable elongation and strongly oblique inclination; 



Figure 693.— Pes of Tel- 

 matherium? ultimum? 



Doubtfully referred left pes, Am. 

 Mus. 1942; Uinta C. One-third 

 natural size. 



