The characters of Pteranodon / by G.F. Eaton.

  • Eaton, George Francis, 1872-1949.
Date:
1903
Catalogue details

Licence: In copyright

Credit: The characters of Pteranodon / by G.F. Eaton. 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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    paleontologists. Three diagrams of this specimen are here given, showing the side, top, and bottom views (Plate VII, fig- ures 1, 2, and ,3, respectively). It is not my intention at this time to enter into a detailed description of the pelvic charac- ters. Indeed, at present, it is necessary to publish little more than the diagrams, which may prevent any further serious misinterpretation of the pelvis. _ Ten vertebne firmly anehylosed together form the sacral series, using this term in its broader sense. The upper ends of the neural spines of all these vertebrm are united in a con- tinuous ridge about 9™' wide and about 0™' in vertical depth (Plate VII, figure 1). The general form of the transverse pro- cesses of the three anterior vertebrm in this series, aTid their union with the ilia, are sutficiently well shown in the accom- panying diagrams (Plate VII, figures 2 and 3). The first verte- bra bears anterior zygapophyses for articulation with the last free dorsal; and the transverse processes of the first tlu-ee vertebrae have on their lower surfaces small facets for the sup- port of ribs. One of these posterior ribs still lies upon the third vertebra, with little displacement from its original position. The transverse processes of vertebrae 4, 5, 6, and 7, de])art widely from the foregoing simple arrangement. They are likewise separated by large foramina, but they unite again laterally and form a continuous support for the ilia. The lower ends of the transverse processes of vertebi’a 4 extend downward and backward, as stout buttresses, finally becoming confiuent with the inferior margins of the ilia. The three remaining vertebrae, nund)ers 8, 9, and 10 of this series, bear short transverse processes, separate at their distal ends, upon which the ilia rest posteriorly. The ilia extend forward as broad, thin blades, supported, at their inner margins, by the transverse processes of tlie anterior sacral vertebrfe. Posteriorly they unite over the neural spines of the last three sacrals, and are anehylosed to them as well as to the transverse processes. The united pubes and ischia are directed downward and backward, and meet belou^ iii a long median symphysis. The obturator foramina lie just beneath the imperforate acetabula. They are circular in form, of about half the diameter of the acetabula, and may be considered as marking the theoretical line of fusion between the true pubic and ischial elements. On the anterior border of these ischio- pubic expansions are small facets, which undoubtedl}^ served for the attachment of prepubes. In no specimen in the Yale Collection has a prepubis yet been found in place. Paleontologists will perhaps disagree on the number and position of true sacrals in Pteranodon. It will be remem- bered that Huxley, when confronted with a similar problem in