12. Bird-Footed Iguanodon, 1857
While Leidy and Cope were discovering fossil bones in the United States, suggesting that dinosaurs were bipedal, naturalists in England were beginning to have similar thoughts. In England, however, fossil footprints played a more important role as a driving force. In 1854, Samuel Beckles had reported finding a number of three-toed footprints in the Weald formations on the Isle of Wight. Beckles was ambivalent as to the source of the tracks; they looked like bird tracks, but he did not rule out the possibility of "ornithic" dinosaurs.
Shortly thereafter, the fossilized hind limb of a young Iguanodon was found on the Isle of Wight by Beckles, who brought it to the attention of Richard Owen. The foot bones were decidedly three-toed, and of the same size as many of the stone footprints. Owen thought the fossil was important enough to warrant a natural-size folding lithograph in 1857. In this paper he did not explicitly connect the Iguanodon foot with the fossil footprints, but in 1858 he did. In a further discussion of this specimen, he said that we must be cautious in assuming that three-toed prints necessarily belong to birds, and he said that the three-toed Iguanodon foot "adds to the probability of Mr. Beckles' ideas" as to the "Iguanodontal nature" of the three-toed fossil prints that have been found in the Weald.
Owen, Richard. Monograph on the Fossil Reptilia of the Wealden Formation. Part IV. London: Paleontographical Society, 1857. Series: Paleontographical Society Volumes, vol. 10 (1856). This work was on display in the original exhibition as item 12.