Recent Progress in Vertebrate Paleontology
W. D. Matthew
 . . . A most important contribution has been added by Gerrit S. Miller 25 to the controversy that has raged around the famous Piltdown skull. Dr. Miller analyzes with care the evidence for and against the association of the skull fragments with the lower jaw and compares the latter with a large series of chimpanzee jaws in the National Museum. He comes to the conclusion that the jaw is in every respect within the limits of individual variation of the chimpanzees, and displays no distinctively human characters, while the skull fragments display in every particular the characters of the genus Homo. Not only is there an entire lack of blending of these two distinct types of skull, but in such parts as should show coordinated characters and adjustment of one to the other, such conformity is wholly lacking.
In the present viewer's opinion [W.D.M.] Dr. Miller's argument is convincing and irrefutable; the jaw belonged to a chimpanzee and the skull to a species of man comparable with that represented by the Heidelberg jaw. It is hardly to be expected, however, that this conclusion will be readily accepted by the European writers, who have with few exceptions committed themselves more or less deeply to the opposite view.
It is quite true, as Professor Boule has observed, that nature affords many instances of unexpected combinations of different types, and no one need be surprised to see an ape-like dentition combined with a man-like brain-case. Indeed, Elliot Smith had adduced excellent reasons why we may well expect to find such a combination. But it is necessary here to distinguish between the concepts of resemblance and identity. The Piltdown jaw is not simply a jaw similar in adaptive specialization to that of an ape, it is a jaw identical with that of the chimpanzee in every particular. The skull is not merely similar in brain-case to that of man, it is the skull of Homo in every particular. For such a combination as this, with its  utter lack of blending, correlation or coordination of interrelated parts, one set of fragments identical with one, the other set identical with another animal of diverse type, not merely similar each to eachsuch a combination is without parallel and is not reasonably possible. To cite a familiar instance, the teeth of the chalicotheres have a general adaptive resemblance to the titanotheres, the skull and neck to the horses, the claws to the edentates. This is a combination quite unexpected, but nevertheless a quite possible one, and of course well proven. But if one should find a jaw identical in every particular with that of Equus and claw-phalanges agreeing in all respects with Mylodon, it would not be reasonably possible that they could belong to a single animal, no matter what arguments of association and distribution were adduced to support such a conclusion.
C. R. Eastman
W. K. Gregory
W. D. Matthew
25 Smithson. Misc. Coll., Vol. 65, No. 12.