OSTEOLOGY OF THE AKMOKED DINOSAUKIA. 



87 



Oalcaneum (c.) . — The calcaneum is represented in the Museum collections by five 

 specimens, of which three are articulated with the tibiae. Viewed externally it is a 

 small angularly rounded element, with the greatest diameter supero-inferiorly. 

 The external surface is compara- 

 tively smooth, being sHghtly con- 

 cave vertically. The tibial side is 

 deeply concave from above down- 

 ward, this surface in the articulated 

 limb closely unitiag with the distal 

 portion of the external malleolus. 

 The bone thins out ]iosteriorly, but 

 thickens anteriorly. The internal 

 border for articulation %vith the as- 

 tragalus is much roughened. The 

 anterior border is regularly rounded 

 from above downward and conforms 

 closely with the convex surface of 

 the astragalus. The proximal end 

 presents a roughenecl beveled ar- 

 ticular surface for the fibula, the 

 bevel being toward the tibial side. 



in figure 60. 



Measurements ofcalcanea 



Fig. 50.— Right calcaneum ok Stegosaueus sp. Cat. no. 

 7367, U.S.N.M. } NAT. size. (I) Lateral view; (2) front 

 view; c, border akticdlating with the astragalus; d, doe- 

 sal BORDER WHICH MEETS THE FIBULA; V, VENTRAL BOEDER. 



The chief features of this bone are well shown 



Greatest antero-posterior border 



Greatest transverse diametor 



Greatest height 



No. 7397, 

 right. 



No. 7398, 

 left. 



No. 6646, 

 right. 



No. 7368, 

 left. 



mm. 



mvi. 



mm. 



mm. 



07 



65 



75 



71 



34 



30 



38 



•11 



7(i 



80 



103 



87 



Metatarsus. — The metatarsus of Stegosaurus consists of four bones, of which 

 three are large and support functional toes, and one is rudimentary (figs. 52 and 53). 



The functional metatarsi are exceedingly stout, robust elements, the median one 

 being the longest of the three. Their proximal ends were evidently bound together 

 by strong ligaments, there being no interlocking articular facets as found on the 

 metatarsals of many of the bipedal Ornithopoda. 



Thefoot of specimen No. 42S0, shown asfound insitu, in plate21, figure 1, appears 

 to have one digit preserved in its entirety. This digit has two phalanges, and on the 

 analogy of other dinosaurian hind feet, as shown in the table below, would indicate 

 that it represents the innermost or firet digit. On the evidence of this one foot it 

 was so regarded when the drawing for figure 52 was made. 



