10. The New Jersey Hadrosaurus, 1858
The teeth identified by Joseph Leidy in 1856 were valid but scanty evidence of North American dinosaurs. Much more dramatic evidence was forthcoming in 1858, when several large limb bones, numerous vertebrae, some jaw fragments, and a few teeth were discovered at Haddonfield, New Jersey, and presented to the Academy of Natural Sciences in Philadelphia. Leidy recognized the fossils as belonging to a dinosaur like Iguanodon, and he named it Hadrosaurus foulkii, after the discoverer and benefactor. More remarkably, Leidy noted the disparity between the long hind legs and the short front legs and concluded: "The great disproportion of size between the fore and back parts of the skeleton of Hadrosaurus, leads me to suspect that this great extinct herbivorous lizard may have been in the habit of browsing, sustaining itself, kangaroo-like, in an erect position on its back extremities and tail." This is the first suggestion anywhere that some dinosaurs might have been, at least on occasion, bipedal.
Leidy's 1858 paper was not illustrated, but in 1865 he published a large monograph that did contain a fairly complete series of plates depicting most of the hadrosaur bones.
Around 1868, Benjamin Waterhouse Hawkins made a restoration of the skeleton for the Academy of Natural Sciences; click here to see a photograph of this restoration.
Leidy, Joseph. "[Remarks concerning Hadrosaurus]," in: Proceedings of the Academy of Natural Sciences of Philadelphia, vol. 10 (1858), pp. 215-218. This work was on display in the original exhibition as item 10.