Proximal end of ulna.

<p><b>A</b>, medial view of proximal end of left ulna and radius of <i>B</i>. <i>feinbergorum</i>, AMNH FR 30554; <b>B</b>, cranial view of proximal end of left ulna and radius of <i>B</i>. <i>feinbergorum</i>, AMNH FR 30554; <b>C</b>, lateral view of proximal end of right ulna of <i>D</i>. <i>antirrhopus</i>, MCZ 8791; <b>D</b>, cranial view of proximal end of right ulna of <i>D</i>. <i>antirrhopus</i>, MCZ 8791; <b>E</b>, cranial view of proximal end of adult <i>D</i>. <i>antirrhopus</i> ulna YPM 5230. <b>Abbreviations</b>: <b>ar</b>, articulating facets; <b>br + hr (?)</b>, possible insertion areas of the M. brachialis and M. humeroradialis from Ostrom [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0121476#pone.0121476.ref001" target="_blank">1</a>]; <b>mf</b>, minute foramina; <b>o</b>, olecranon; <b>R</b>, radius; <b>scas</b>, smooth cortical articular surface; <b>U</b>, ulna.