. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 256 Bulletin Museum of Comparative Zoology, Vol. 139, No. 5. 5 cm A B Figure 8. Pelves of one varanopsid pelycosaur and one protero^uchian thecodont. A, Varanops brevirostris (Williston) (from Romer and Price); B, Vjushkovia frip/icosrafa von Huene (from von Huene). the position where the entepicondylar fora- men should be placed, which suggests that such a foramen might be present in this genus, its external bridge of bone being broken in the specimen. An ectepicondylar notch is also evident. The anterior epipodials
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 256 Bulletin Museum of Comparative Zoology, Vol. 139, No. 5. 5 cm A B Figure 8. Pelves of one varanopsid pelycosaur and one protero^uchian thecodont. A, Varanops brevirostris (Williston) (from Romer and Price); B, Vjushkovia frip/icosrafa von Huene (from von Huene). the position where the entepicondylar fora- men should be placed, which suggests that such a foramen might be present in this genus, its external bridge of bone being broken in the specimen. An ectepicondylar notch is also evident. The anterior epipodials are short and subequal in size both in pelycosaurs and proterosuchians. The former have a well- developed olecranon on the ulna, which is apparently lacking in the proterosuchians. But, as Romer and Price have indicated (1940: 46), the extreme lag in ossification of the olecranon during ontogeny makes this character untrustworthy in problems of phylogeny. It is suggestive that the ulna of Varanops looks very much like that of Chasmatosaurus described and figured by Young (1936), especially as regards the proximal end, which in both is massive and has a relatively weakly developed ole- cranon area. We have already said that the pelvic girdle of the primitive proterosuchians may be better described as incipiently triradiate, the triradiate condition being more evident in such advanced forms as Erythrosuchus. Earlier forms retain many primitive char- acteristics, such as a reduced but fairly continuous puboischiadic plate. The pubis in Varanops (Fig. 8) has a very strong upper border directed forwards and down- wards, and can be described as a twisted plate of bone, as is the case in the protero- suchians. The ischium also shows a strong upper border directed backwards and downwards, and the puboischiadic plate is reduced. These features are closely com- parable to those in primitive protero- suchians and suggests that the archosaurian trend toward a triradiate pelvis was beginnin
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