666 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



narrow unciform facet (14 mm.) (this facet is broader 

 in B. roiustus); Mtc IV occupying main portion of 

 unciform; Mtc V articulating chiefly with the outer 

 side. 



The linear measurements of the metacarpals are as 

 follows: Mtc II, 155 milUmeters; Mtc III, 176; 

 Mtc IV, 174 (?); Mtc V, 137. The proximal phal- 

 anges are very broad and large; the median phalanges 

 are short. The distal phalanges are relatively smaller 

 than in B. roiustus, expanded transversely and of 

 short linear dimensions; the widths are, Ph II, 43 

 millimeters; Ph III, 45; Ph IV, 46; Ph V, 38. 



Pelvis and hind limb. — Massive as the pelvis is, its 

 intermediate character is indicated by the fact that 

 the total length of the innominate bone is 809 milli- 

 meters, as compared with the total breadth of 925 

 millimeters across the two ilia; the posterior opening 

 is correspondingly elongate vertically. The hind 

 limb as compared with the fore limb is long and 

 slender, with the following principal characters: 

 Femur with projecting head, feebly marked third 

 trochanter directly opposite second trochanter, and 

 both well down on the shaft, inner patellar facet 

 much more elevated than outer, patella vertically 

 elongate, inner condyle of the femur much the largest. 

 Tibia relatively elongate and less massive than in B. 

 roiustus, shaft of fibula much reduced superiorly. 

 Pes as a whole decidedly slender; tarsus having a 

 breadth of 110 millimeters across cuboid and navic- 

 ular; tuber calcis not placed transversely; astragalu.i 

 with a relatively long neck; navicular and cuboid 

 relatively deep; metatarsals of medium length and 

 slenderness, surprisingly light in structure; Mts II 

 not abutting against ectocuneiform as in B. roiustus; 

 Mts III with a very oblique lateral facet for cuboid 

 (differing widely from the broad facet in B. roiustus) ; 

 proximal phalanges long and rather narrow; distal 

 phalanges moderately broad. 



Brontops robustus Marsh 



Type specimen. — Our knowledge of Brontops roiustus 

 is based on the superb type specimen in the Peabody 

 Museum at Yale University (Yale Mus. 12048) which 

 was discovered and unearthed by Mr. H. C. Clifford 

 in 1875 in the upper Titanotherium zone near Chadron, 

 Nebr. It was appropriately made the type of Brontops 

 roiustus by Marsh, and it is very fully illustrated in 

 Plates XCVI-CIII, CXCV-CCXXIX of this mono- 

 graph. As noted in detaQ below, certain of the plates 

 and the very remarkable restoration by Berger under 

 Marsh's direction (PI. CCXXIX) include bones that 

 were derived from other specimens. In 1916 this skel- 

 eton was mounted under the direction of Prof. R. S. 

 Lull, who gives the following measurements: Height 

 at shoulder, 8 feet 23^ inches ( = 2.502 meters)*"; 



« In Professor Lull's judgment this measurement is probably 3 or 4 inches too 

 great — that is, the backbone as mounted is too high. 



length over all, following vertebral column, 15 feet 

 2}/^ inches ( = 4.635 meters); length between per- 

 pendiculars to base of tail, 11 feet ( = 3.353 meters). 



Of the presacral vertebrae 26 are preserved — 7 

 cervicals, 17 dorsals, and 2 lumbars — in a continuous 

 series, the third or posterior lumbar being apparently 

 missing. 



The characters of the cervicals in lateral view are 

 accurately represented in the restoration forming 

 Plate CCXXIX and in Figure 610, A. 



The atlas (PI. CXCV, figs. 1-5) measures 465 milli- 

 meters transversely, 158 vertically, 278 across the 

 axis facets; the neural arch is perforated at the side 

 for the exit of the first cervical nerve, which passes 

 down anteriorly in a deep notch between the junction 

 of the condylar cup with the transverse process (figs. 

 2, 4); the transverse processes (ribs) are moderately 

 robust, not very widely expanded anteroposteriorly, 

 somewhat truncate or square distally; the neural 

 spine is sessile and slightly grooved but not bifid 

 posteriorly. The axis (PI. CXCVI) measures 270 milU- 

 meters transversely, 290 vertically, the outside 

 measurement of the posterior face of the centrum 

 being transverse 137, vertical 119; the superior bor- 

 der of the spine is acutely convex and slopes obliquely 

 backward, slightly overhanging the centrum pos- 

 teriorly; the antero-inferior face is abruptly trun- 

 cate; the odontoid is short; the atlanteal facets are 

 continuous, the median area being transverse, the 

 lateral areas oblique and flaring. In C. 3-7 (PI. 

 CXCVII) the neural spines increase regularly in height, 

 that in C. 7 being pointed but entirely different in 

 character from the spine of D. 1 ; the prezygapophyses 

 and postzygapophyses are flattened and face upward 

 and inward, and downward and outward; the lami- 

 nae of the neural arches increase gradually in width 

 as seen from above in C. 3-C. 7. The cervical 

 transverse processes or ribs (pleurapophyses) in C 3 

 exhibit a broad, thin plate; in C. 4 a rugose superior 

 and small flat inferior lamella; in C. 5 rugose and 

 subequal superior and inferior lamellae; in C. 6 a 

 rugose superior lamella and widely expanded, antero- 

 posteriorly flattened inferior lamella; in the im- 

 perforate 'C. 7 the inferior lamella is entirely wanting. 



Proportions of presacral centra. — The comparative 

 measurements on page 667 bring out the following char- 

 acters in the proportions of the centra. The short, 

 deeply opisthocoelous cervical centra (C. 3-7) range 

 from 650 to 700 millimeters in length, from 107 to 114 

 in width, and from 106 to 113 in height, practically 

 as high as broad. The dorsal centra are less deeply 

 opisthocoelous; they are longer than the cervicals, 

 ranging from 73 to 88 millimeters in length; in the 

 anterior dorsals (PI. CXCVIII) the vertical exceed 

 the transverse measurements, correlated perhaps with 

 the spines; in the middle and posterior dorsals the ver- 

 tical are less than the transverse measurements. 



