Licence: In copyright
Credit: On the primitive reptile Procolophon / by H.G. Seeley. Source: Wellcome Collection.
Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.
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![not exposed. Among the materials for which I am indebted to Dr. Schonland is a slab (showing no conclusive evidence of the characters of Procolophon) with remains of vertebrae and ribs of a young animal, in which the humerus, ulna and radius, and scattered bones of the extremity are preserved. The proximal end of the humerus is but little seen, the shaft is twisted, and the distal end of the bone expanded as in Anomodonts, with a large entepicondylar foramen, and on this side of the distill articulation the bone is rounded in contour as in Dicynodonts. The ulna and radius are slightly shifted in position, but are parallel bones which are shorter than the humerus. I suppose the bone which is stouter proximally to be the ulna, and that the slender bone is the radius, which appears to widen distally. Conclusion. The evidence from all parts of the skeleton points towards similar conclusions. The skull, with its general affinity with Anomodont reptiles, comes closer to the Pareiasauria in the relation of the quadrate region to the back of the head, and closer to the Theriodonts in dentition. The shoulder-girdle is also suggestive of the Pareiasauria, but the permanent separation of all the bones and the great anterior development of the pre- coracoid are distinctive characters. There is a similar affinity in the pelvis and in the hind limb and fore limb, but the differences point in all cases to a relation with groups which have Labyrin- thodont affinities. The evidence is too imperfect to justify a final determination of relationship with all the Permian and Triassic Iteptilia, but it sustains the conclusion that the order Procolo- phonia was based upon substantial differences of this type from its allies. [14]](https://iiif.wellcomecollection.org/image/b2241292x_0018.jp2/full/800%2C/0/default.jpg)
