Fig. 10. A in Quadrupedal dinosaurs did not evolve fully pronated forearms: New evidence from the ulna

Fig. 10. A comparison of the semi-pronated distal antebrachial epiphyses of select archosauromorphs and basal archosaurs. A. Archosauromorph, Trilophosaurus buettneri Case, 1928 (TMM 31025-140), reversed. B, F. Phytosaur, Machaeroprospus pristinus (Mehl, 1928) (B, UCMP 121989; F, UCMP 121982). C. Phytosaur, Heterodontosuchus ganei Lucas, 1898 (USNM 2159). D. Aetosaur, Typothorax coccinarum Cope, 1875 (NMMNH L-5806). E. Rauisuchid, Postosuchus alisonae Peyer, Carter, Sues, Novak, and Olsen, 2008 (cast of UNC 15575). G. Aetosaur, Typothorax antiquum Lucas, Heckert, and Hunt, 2002 (NMMNH P-36075). H. Aetosaur, Desmatosuchus haplocerus Cope, 1892 (UCMP 25838). I. Rauisuchid, Postosuchus kirkpatricki Chatterjee, 1985 (TTU P9000). Phytosaur elements oriented after M. pristinus (UCMP 27235), aetosaur elements oriented after T. coccinarum (NMMNH L-5806). Note that nearly all specimens possess torsion of the distal ulnar diaphysis that effectively supinated the distal ulnar articular surface, and that most (except A, B) also exhibit pre-axial elongation of the distal radial epiphysis. Note also, however, that specimen A possesses distorted radial and ulnar diaphyses, so the orientation of the distal ulnar epiphysis may not be vertical as shown. Not to scale.