676 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



The appendicular skeleton 



Fore limh. — While both scapulae are incomplete, the_v supple- 

 ment each other so that our knowledge of them is fairly perfect. 

 The proximal half of the left with its spine is well preserved, 

 while of the right nearly the entire distal border is present. 



The glenoid is deeply concave anteroposteriorly and is broadly 

 elliptical in outline. The coracoid process is conical, somewhat 

 downwardly curved at the tip, separated by a deep notch from 

 the glenoid border, and not arising directly from it, as in 

 Palaeosyops, but separated by an interval of 38 millimeters. 

 The spine is high in the middle, with a broad roughened border. 

 It lowers insensibly into the general level of the scapular face 

 above and below, with no indication of an acromion. The tuber- 

 osity is not very pronounced, and the distal border is nearly 

 straight. 



Millimeters 

 Breadth of shaft 85 



Fore-and-aft diameter of shaft 77 



The radius. — That of the left side is well preserved, except 

 that its distal end is somewhat weathered. It is not notably 

 heavy and has a well-rounded shaft, bat sUghtly compressed 

 fore-and-aft at the distal end. The radioscaphoid facet is pro- 

 longed upward on the posterior face, indicating a considerable 

 range of flexion of the wrist. 



The principal dimensions of the radius are: 



Millimeters 



Length 490 



Anteroposterior diameter of mid shaft 60 



Lateral diameter of mid shaft 65 



Lateral diameter of lower end 110 



Figure 610. — Mounted skeleton of Brontops hrachycephalus? 



la the Victoria Memorial Museum, Ottawa, Canada. Collected on Sage Creek, Niobrara County, Wyo., probably 

 from the lower Titanotherium zone (Chadron A). One complete individual except the left femur, right radius and 

 ulna, and a few foot bones. Maximum height 6 feet 6 inches. Courtesy of Charles M. Sternberg. Less than one- 

 twentieth natural size. 



The dimensions of the scapula are: 



Millimeters 

 Total length (estimated) 690 



Width of superior border (estimated) 405 



Fore-and-aft diameter of glenoid fossa 133 



Height of spine 95 



The humerus. — The distal portions of both humeri are pre- 

 served, but of the proximal portions that of the right only, 

 and as there is a portion of the shaft missing, the length can 

 not be measured. The distal end is broad and heavy, the ex- 

 ternal condyle being especially prominent and roughened for 

 muscular attachment. The inner trochlear is much the larger 

 and is higher than the outer one, thus indicating an outward 

 flexing of the elbow joint. The aconeal fossa is large and deep, 

 but there is no foramen. The breadth of the extremity meas- 

 ured at right angles to the axis of the shaft is 210 millimeters. 



The ulna. — The entire left and fragments of the right are 

 preserved, except for the distal end of the former, which is 

 badly weathered. The ulna is notable for its huge compressed 

 olecranon, which widens out distally into a heavy roughened 

 tubercle. 



The ulna measurements are as follows: 



Millimeters 



Length (estimated) 620 



Anteroposterior diameter of olecranon from 



the humeral facet 170 



Lateral diameter of olecranon tubercle 140 



Fore-and-aft diameter of mid shaft 80 



Lateral diameter of mid shaft 80 



The maniis (PI. IV, figs. 1-3). — The general proportions, well 

 shown in the figure, are somewhat broad rather than slender 

 and in direct correlation with the proportions of the skull. 



