Page:Notes on Osteology of Baptanodon. With a Description of a New Species.pdf/8

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With specimen 603 in the collection of the Carnegie Museum is a portion of a bone which at the time of preparing my  on Baptanodon I was unable to identify but since have concluded that it represents the acetabular end of the ilium. This end is expanded into a thickened head somewhat roughened on the acetabular surface. The shaft above the head is constricted up to the fractured end, both antero-posteriorly and internally. One side of the bone is flattened and probably represents the internal surface. The fractured end is nearly half oval in cross-section. (See (3), Fig. 11.) If correctly determined this is the first evidence we have of the character of the pelvic region in Baptanodon and it appears to indicate a weak posterior extremity as compared with the strong anterior limb. It also furnishes additional evidence that Professor Marsh was mistaken in his identification of the limb in the type of B. discus (1955) as a posterior extremity, a question dis-cussed in my previous paper. This element resembles somewhat the ilium of , a Ichthyosaurian described by Dr. J. C. Merriam.

The type material of this species includes a fairly well-preserved, a series of ten cervical vertebræ beginning with the atlas ; a second series of eleven vertebne from the anterior dorsal region commencing back of the point where the diapophysis becomes distinct from the articular surface ; a third section of eleven posterior dorsals beginning just back of the first vertebræ having the diapophysis and parapophysis united to form a single -like articulation for the single headed- of this region. The fourth and last section contains parts of twelve anterior caudals. These show the rapid decrease posteriorly in the size of the centra, which has been previously pointed out by Knight.

This specimen, No. 919, is from the Red Fork of, ,