On Protorosaurus speneri (Von Meyer) / by H.G. Seeley.

  • Seeley, H. G. (Harry Govier), 1839-1909.
Date:
1887
Catalogue details

Licence: Public Domain Mark

Credit: On Protorosaurus speneri (Von Meyer) / 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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    such as is seen in Crocodiles and Lizards, but the great oblong plate which extends outward to the quadrate bone must have been attached along much of the length of that bone. The quadrate bone.—Posterior to the pterygoid bone is a much stronger bone, imperfect at both ends, which I regard as the quadrate bone. As preserved, it is 1’4 centim. long. It is somewhat compressed, constricted in the middle, and expands proximally to a width of 4 millims. It has an internal expansion which is not fully seen, which is wide, thin, and oblique, and appears to be the pterygoid process. The surfaces of the quadrate bone are smooth, and concave in length in every direction in which exposed. The loiver jaw.— The lower jaw has its constituent bones displaced. As preserved, it is about 9 centims. long, and measures 8 5 centims. from the articulation for the quadrate bone to the extremity of the dentary bone. There is no indication of a coronoid process. It is long and narrow, increasing a little in depth as it extends backward, but becomes less deep again towards the posterior articulation. The out- line is straight along the dentary border, and slightly convex below. Both dentary bones are present, and show that they had only a narrow union at the extremity of the jaw, and were not anchylosed together. The e.xtreme length of the dentary bone was probably about G-5 centims. The angular and surangular were both elongated bones. The splenial bone appears to have lapped along the inner side of the jaw and extended forward to near the extremity of the dentary bone. The articular bone is lunate, 8 millims. long; not unlike this bone in the Crocodile, with a transverse concave articulation. The bone, though now exposed, was probably imbedded. Twenty-seven teeth can be counted apparently anchylosed to the dentary bone, extending along a border of more than 4 centims. Other teeth may have been present further back. Hyoid bones.—Between the articular end of the lower jaw and the displaced quadrate and pterygoid bones are slender, delicate, straight, cylindrical bones, very imperfectly displayed, which are jointed. Their slenderness and position are suggestive of the hyoid elements. The length exposed is 2*2 centims. The structure apparently consists of a rod measuring 1'8 centim. and two short joints of about 2 millims. each. The terminal joint is conical. The vertebral column.—The vertebrae extend in a continuous curve, with the neck bent round so as almost to meet the sacrum ; beyond which the tail extends, at first gently curved, and then almost straight. About 59 centims. of the vertebral column are preserved, but a portion of the tail, of unknown length, is lost. The cervical vertebrce.—The cervical vertebrae are conspicuously elongated (Plate 14, 2-7). Six are preserved in connected sequence. Measured round the curve, they have an aggregate length of 13 centims. The Atlas does not appear to be preserved, or, if preserved, is broken, and the fragment out of position and imbedded in matrix. As the first of the series is the short Atlas, this animal appears to have had seven cervical vertebrae. Being in close union by means of the several articular processes,