Further observations on Pareiasaurus / by H.G. Seeley.

  • Harry Govier Seeley
Date:
1892
Catalogue details

Licence: Public Domain Mark

Credit: Further observations on Pareiasaurus / 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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    of the shoulder girdle was supported. It is possible that the specimen is imperfect at the base since the bone is there 2| inches thick, and narrows anteriorly. The posterior half of the coracoid forms the great semi-cylindrical concavity for the humerus, which is notched at the basal margin, both in front and behind, but marked inferiorly by an elevated border, similar to the edge of the scapular part of articulation. The bone becomes rapidly thinner in front, so that at the anterior border, which is convex in outline, the thickness is more than half an inch, and it is thin toward the junction with the precoracoid. It terminates toward the interclavicle in a sharp border, rounded from above downward. There is no certain evidence whether it met the interclavicle at the margin, or passed behind it as in Ich thyosaurus/' The clavicular arch Clavicular arch of Pareiasaurus Baini, seen from the front, in natural union with the shoulder girdle as found, ic. interclavicle, cl. clavicles, sc. scapula, pc. precoracoid, cor. coracoid, f. foramen. consists of a clavicle, interclavicle, and epi-clavicle. The interclavicle (ic.) is a strong T-shaj^ed bone, broadly expanded at the superior transverse bar, and giving attachment upon this flattened surface to the clavicles (cL), which extend outward and backward in a curve to the scapulte (sc.). T here is no indication that the clavicle was embedded in the interclavicle in the way shown in P. hombidens. The transverse bar of the inter- clavicle measures round the convex curve 19 inches ; its median depth, as preserved, in about 9 inches. The interclavicle was prolonged downward and backward in a flat, wide, median bar, comparable to that seen in the interclavicle of Procolophon and Keirognathus. It therefore may be anticipated in all Anomodonts, though not * [A similarly thin median margin to the coracoid is found in Mesosmirus, which may possibly imply overlap of those hones.—July, 1892.]