Archive image from page 109 of The dinosaurs of North America The dinosaurs of North America dinosaursofnort00mars Year: 1896 234 DINOSAURS OP NORTH AMERICA. worthy differeuce from all the existing crocodiles. The hind foot, how- ever, is of the crocodilian type, with the calcaueuin showing a posterior projection. In Belodon, only the pelvis of which is here represented (fig. 62), the pubis contributes a very important part to the formation of the acetabulum, and to the entire pelvic arch. The latter differs from the pelvis of a typical dinosaur mainly in the absence of an open acetabu- lum,
Archive image from page 109 of The dinosaurs of North America The dinosaurs of North America dinosaursofnort00mars Year: 1896 234 DINOSAURS OP NORTH AMERICA. worthy differeuce from all the existing crocodiles. The hind foot, how- ever, is of the crocodilian type, with the calcaueuin showing a posterior projection. In Belodon, only the pelvis of which is here represented (fig. 62), the pubis contributes a very important part to the formation of the acetabulum, and to the entire pelvic arch. The latter differs from the pelvis of a typical dinosaur mainly in the absence of an open acetabu- lum, but a moderate enlargement of the fontanelle at the junction of the three pelvic elements would practically remove this difference. A more erect position of the limb, leading to a more distinct head on the femur, might possibly bring about such a result. The feet and limbs of Belodon are, crocodilian in type. Bearing these facts in mind, the diagram representing the restored fore and hind limbs of the diminutive Hallonus (figs. 59-GO) shows first Fig. 62.—Diagram of pelvis of Belodon Kapfi von Meyer; seen from tlie left. One-fourth natural size. «, acetabular surface within dotted line; il, ilium; is, ischium;, pubis. of all the true dinosaurian pelvis, with the pubic bone taking part in the open acetabulum, and forming an important and distinctive element of the pelvic arch. The delicate posterior limb and foot, evidently adapted mainly for leaping, as the generic name suggests, are finite unique among the Reptilia, but the tarsus, especially the calcaneum, recalls strongly the same region in the orders already passed in review. Just what this posterior extension of the calcaneum signifies in this case it is difficult to decide from the evidence now known. It may be merely an adaptive character, as Hallopus appears in nearly every other respect to be a true carnivorous dinosaur. It may, however, be an inheritance from a crocodilian ancestry, preserved by a peculiar mode
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