fact was actually so; that reptiles once existed which walked upon their hind-legs as birds now do. The diagram is a faithful and accurate representation of an existing fossil except for this, that, whereas in the existing fossil the bones are twisted about and out of place, I
have put them here in the position that they must have had in nature. You see a creature with a long neck and bird-like head, with very small anterior extremities, and that compsognathus creature must assuredly have walked about upon its hind-legs, bird-fashion. Acid to this feathers, and the transition would be complete. Now to define it: The possession of teeth would, as we see, not separate this animal from the class of birds we have. We have had to stretch the class of birds so as to include birds possessed of teeth, and, so far as the character of the skeleton goes, we may fairly say that there needs here little more than the addition of feathers—and whether this creature had them or not we don't know—to convert it into a bird.
I have said that there can be no question, from their anatomical structure, that these animals walked upon their hind-legs, and, in fact, there are to be found in the Wealden strata of England gigantic foot-steps arranged in order like these of the Brontozoum, and which there can be no reasonable doubt were made by Dinosauria, the remains of which were found in the same rock. And, knowing that reptiles that walked upon their legs and shared many of the anatomical characters of birds did once exist, it becomes a very important question whether those tracks in Massachusetts—to which I referred just now, and which formerly used to be unhesitatingly ascribed to birds—may not all have been made either by reptiles similar to the Dinosauria, or whether, if we could get hold of the skeleton which made these