Iguanodon

Abstract

SINCE I wrote the account of M. Dollo's researches on Iguanodon, which appeared in NATURE of September 6 (p. 439), I have had the advantage of some conversation with Prof. Marsh on the subject, and am anxious to state one or two matters which I learned from him concerning questions raised in my review. Prof. Marsh has visited Brussels since I was there, and since M. Dollo's memoirs referred to by me were in print, and has examined the Iguanodon skeletons with M. Dollo, this being the second occasion on which he has seen the collection. After having examined the specimens now available he is of opinion that the question whether the bones considered by M. Dollo to be sternal are in reality such, or clavicles, is still an open one. The form of the bones, which are undoubtedly identical with those in the British Museum specimen determined by Prof. Marsh to be clavicles, is exactly that of clavicles and unlike that of any known sternal bones. There can be no doubt that they belong to the pectoral arch, but the position in which they have been found in two Bernissart specimens points to their belonging rather behind than in front of the coracoids. It is, however, Prof. Marsh believes, just possible that they may have fallen forward into the position in which they there occur, and he awaits the results to be attained from their examination in the other Bernissart specimens before making up his mind. In the closely-allied Hypsilophodon the sternum is a single broad-keeled plate. In the case of the British Museum specimen one of the bones is attached to the scapula. At all events, he points out that, should these bones really prove to be sternal, it does not follow that Iguanodon had no clavicles at all, for there is a process on the scapula indicating the presence of a clavicle, and such a bone, possibly very small and rudimentary, may yet be found to exist.