25. Sprawling Diplodocus, 1910
Not everyone agreed with Osborn, Cope, and Knight that dinosaurs were nimble browsers and agile hunters. Oliver Hay, in particular, thought that making dinosaurs stand and act like mammals was an abuse of anatomical fact.
Hay argued that ornithopods like Trachodon must have had a very wide stance, so that the legs could clear the pendulous abdomen, and consequently they must have waddled rather than strode. And he took particular issue with reconstructions of Diplodocus--not just Knight's rearing version, but also Hatcher's upright, elephantine restoration.
After studying the structure of the upper leg and the pelvis, Hay concluded that the legs of Diplodocus must have splayed out like those of a crocodile. For this paper he commisioned a drawing from Mary Mason Mitchell to reflect his views of diplodocid posture.
There are four individuals in all in the drawing; the two in the foreground are quite unmistakable; there is a third that is swimming in the water, with just its head and back visible, and a fourth lies sprawled out on the distant bank (see detail at left).
Hay first proposed his ideas on Diplodocus posture in 1908, and he received ardent, and perhaps unwelcome, support from an anatomist in Germany, Gustav Tornier.
Tornier and Hay were then attacked rather scathingly by William J. Holland in 1910.
Hay, Oliver P. "On the manner of locomotion of the dinosaurs, especially Diplodocus, with remarks on the origin of the birds," in: Proceedings of the Washington Academy of Sciences, vol. 12 (1910), pp. 1-25. This work was on display in the original exhibition as item 25.