Comparison of the femora of hesperornithiforms in lateral view (left-to-right: Fumicollis hoffmani UNSM 20030; Hesperornis regalis YPM 1200; Baptornis advenus AMNH 5101).

1, arrow indicates the expanded bulge to the cranial surface of the distal shaft seen in F. hoffmani and H. regalis but not in B. advenus. 2, arrow indicates the narrowing of the distal lateral shaft into a neck proximal to the lateral condyle. The degree of narrowing is most extreme in F. hoffmani, present to a lesser degree in H. regalis, and nearly absent B. advenus. Insets are shown scaled to be of similar size to F. hoffmani. Abbreviations: g, scar for the gastrocnemial muscle; lc, lateral condyle.