630 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



massive than in the type of L. laticeps; the ulna, 

 including the olecranon, measures 288 millimeters; 

 the radial shaft 220. Distally the combined radio- 

 ulnar facets for the carpus measure 70 millimeters. 

 A part of the left manus is also preserved. 



Hind limb. — The hind lunb from the head of the 

 femur to the ankle joint measures 642 millimeters. 

 The pes is unfortunately unknown. The femur is a 

 long (376 mm.), rather slender bone, greatly exceed- 

 ing the tibia (270 

 mm.) in length, as in 

 all slow-moving ani- 

 mals. Both these 

 bones are readily 

 distinguished from 

 those of Palaeosyops 

 leidyi by their more 

 slender proportions. 

 The femur has the 

 long, straight form 

 characteristic of 

 titanotheres gener- 

 ally, with the second 

 and third trochan- 

 ters nearly opposite 

 each other in the 

 upper portion of the 

 shaft; distally the 

 patellar trochlea 

 points obliquely for- 

 ward. Thepatellais 

 a relatively smaller 

 element than in 

 Palaeosyops leidyi 

 (transverse 40 mm., 

 vertical 56). The 

 tibia also exhibits a 

 slender shaft. In 

 general these limbs 

 are distinguished 

 from those of Pal- 

 FiGURE 550.— Right hind limbs of aeosyops leidyi by 



their greater slen- 

 derness, from those 



Palaeosyops major and P. copei? 



A, P. major, Am. Mus. 13116; Bridger B 3; femur 

 and tibia. B, P. copei?, Am. Mus. 12205; Bridger 

 D 1; femur, tibia, and fibula. One-sixth natural of LimnohyopS lati- 



^'^'^' ceps by their inferior 



length. The astragalus (fig. 547) is of palaeosyopine 

 type. 



Another more adult skeleton (Am. Mus. 12205) 



Another skeleton (Am. Mus. 12205) was found with 

 the one described above, at Lone Tree, Henrys Fork 

 Bridger Basin, Wyo., level Bridger D 1. It is larger 

 and belongs to a fully adult individual, the tibia 

 measuring 300 millimeters as compared with 270 in the 

 specimen just described. 



Fore limb. — By far the most important part of this 

 skeleton is the fore limb. The total length of the ulna 



is 326 millimeters, that of the radius 235; the transverse 

 radio-ulnar carpal facets measure 85. 



Manus. — Three very distinctive characters are 

 found in the manus as compared with that of Palaeo- 

 syops leidyi — (1) the abbreviation of Mtc V; (2) the 

 relatively elongate form of the distal phalanges as 

 compared with those of Palaeosyops; (3) the broader 

 displacement of the lunar on the unciform and its 

 narrower facet on the magnum. These features are 

 correlated with narrower hoofs, somewhat greater 

 speed, and slightly more mesaxonic disposition of the 

 metacarpals. The transverse measurement across the 

 top of the carpus is 89 millimeters. The scaphoid 

 rests on the trapezoid and magnum only, because the 

 trapezium, though well developed, articulates with 

 Mtc II and the trapezoid only. The lunar is narrower 

 (32 mm.) superiorly than that of P. leidyi and in- 

 feriorly is readUy distinguished by its narrow and 

 nearly vertical facet for the magnum and relatively 

 broad and horizontal facet on the unciform. The 

 cuneiform measures 40 millimeters superiorly. The 

 magnum is a much smaller bone than in Palaeosyops 

 leidyi, subquadrate in form, with a short (16 mm.) 

 oblique continuous facet for the lunar and unciform. 

 The metacarpals measure, Mtc II, 96 millimeters; 

 Mtc III, 106; Mtc IV, 93; Mtc V, 74. This animal 

 was therefore decidedly short-footed ; the median meta- 

 carpal in the contemporary Palaeosyops leidyi meas- 

 ures 116 millimeters. The form of the distal pha- 

 langes is somewhat more elongate and less expanded 

 distally than in Palaeosyops. 



Femur. — The femur exhibits the lesser and third 

 trochanters directly opposite each other; distally it 

 measures 90 millimeters across the condyles. 



Tibia. — The tibia is finely preserved. The femoral 

 facets measure 87 millimeters (tr.), the astragalar 

 facets 43 (tr.) the shaft 31 (tr.) by 33 (ap). 



Measurements of limb bones referred to Palaeosyops, in Tnillimeters 



P. leidyi, 



Am. Mus. 



1544 (com- 

 posite 



slceleton), 

 Bridger 

 C(?), D 



Humerus, length 



Radius, length 



Radius, breadth, proximal end 



Radius, breadth, distal end 



Ulna, length 



Carpus, width 



Mtc II, height 



Mtc III, height 



Mtc III, greatest width, distal. 



Mtc IV, height 



Mtc V, height 



Femur, length 



Tibia, length 



325 

 235 



63 



67 

 315 



96 

 106 

 113 



45 

 102 



75 

 370 

 290 



