On Patricosaurus merocratus from the Cambridge Greensand.
- Harry Govier Seeley
- Date:
- 1887
Licence: Public Domain Mark
Credit: On Patricosaurus merocratus from the Cambridge Greensand. 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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![On Patricosaurus merocratus, Seeley, a Lizard from the Cam- bridge Greensand, preserved in the Woodwardian Museum of the University of Cambridge. By H. G. Seeley, F.E.S., F.G.S., Professor of Geography in King’s College, London. [Plate XII.] Ko Iacertilian has hitherto been recorded from the Cambridge Greensand. The comparative rarity of this gronp of animals in the deposit is evidenced by the fact that only two fragments of lizard- bones are known to me to have been fonnd during the whole period in which its fossils have been collected. One of these is a sacral vertebra with the transverse processes broken away, which was, I believe, collected by the Ilev. H. G. Day prior to 1859. The other is the proximal end of a femur obtained recently by Mr. A. F. Griffith. Slight as is the material, it is worth recording as evidence of a terrestrial animal of a relatively large size, and more nearly allied to existing lizards than are the other Cretaceous representa- tives of this order of animals. Eight Femur (PI. XII. figs. 9, 10). The proximal end of the right femur now described is larger than the corresponding bone in the largest existing Monitor. It was unfortunately fractured, subsequently to being mineralized, at a point below the articular head, just where the shaft becomes trian- gular, so that the length of the bone and its distal characters are entirely conjectural. The shaft consists of dense bony tissue, as in existing lizards, with a small medullary cavity. The fragment is about 3 centim. long. It has the characteristic vertical compression and forward curvature of the convex articular head, and the usual front-to-back compression of the inferior trochanter, which, however, extends further proximally than in existing lizards. The fragment has experienced a little attrition, and a thin external epiphysial layer of bone is partly removed from the proximal articular surface— a character of some interest as repeating the epiphysial growth which is often seen in existing lizards, but in a form no thicker than in the limb-bones of some breeds of domestic fowls, like Bramahs, when a week or two old. The proximal articular surface is semicircular from front to back; it is 2 centim. wide. Its superior outline, viewed from the proximal end, is comma-shaped, being a centimetre wide in front, and becoming narrower as it extends backward. From above downward the articulation is convex, about 12 millim. thick in the middle, and narrowing away behind. The convexity of the anterior part of the smooth rounded articular head is suggestive of the limb having been carried in a position well raised from the ground. The axis of the articular head of the bone is directed inward and very slightly](https://iiif.wellcomecollection.org/image/b22412578_0004.jp2/full/800%2C/0/default.jpg)
