Huxley, Dinosaurs, and Birds, 1868
It was Thomas Huxley who first brought recent dinosaur discoveries to the service of Darwinian evolution. Huxley had already argued, because of anatomical similarities, that birds and reptiles were descended from common stock. Now he had fossil evidence that dinosaurs might have provided the link. In a lecture in 1868, Huxley explained how to read the evidence. Iguanodon had three strong toes on its hind limbs and could clearly support itself on those toes; moreover, Beckles had found footprints the right size and distance apart for an Iguanodon. Therefore, Iguanodon could evidently walk on its hind legs.
Archaeopteryx was another piece of evidence for Huxley; it appeared to be a bird, but it was a transitional bird, with many reptilian features.
But it was Compsognathus that really impressed Huxley. It was an extremely bird-like dinosaur.
"It is impossible to look at the conformation of this strange reptile and to doubt that it hopped or walked, in an erect or semi-erect position, after the manner of a bird."
Huxley's lecture was published immediately, but the printed paper was not illustrated. However, when Huxley later went on a lecture tour of the United States, he evidently prepared a drawing of how he would reconstruct Compsognathus, because Othniel C. Marsh made a copy, and he finally published the drawing in 1895. The illustration thus shows Marsh's version of Huxley's restoration of Compsognathus.