On Pareiasaurus bombidens (Owen), and the significance of its affinities to amphibians, reptiles, and mammals / by H.G. Seeley.

  • Seeley, H. G. (Harry Govier), 1839-1909.
Date:
1888
Catalogue details

Licence: Public Domain Mark

Credit: On Pareiasaurus bombidens (Owen), and the significance of its affinities to amphibians, reptiles, and mammals / 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.

    4/76 (page 60)
    remarks,* it is a trace of a lower grade of vertebral structure, and ‘recalls the more widely perforated, still less ossified, centrums of the vertebrae of Ganocephalous Reptiles of the Carboniferous Series represented by Parabatrachus, Hylonomus, Dendrerpeton, &c/ The ribs are double-beaded, with a parapophysial articulation on the centrum, a diapophysial facet on the neural arch.t The scapula and coracoid are said to be anchylosed together. The humerus is described as relatively broader than in Omosaurus, rather suggesting the breadth of the bone in the Mole. The bone is solid. Other parts of the skeleton are identified ; but no further suggestions are made as to the organic relations of the type. About nine years ago the ‘ masons ’ in the British Museum, under the skilful direction of Mr. William Davies, F.G.S., removed the matrix from the skull and axial skeleton of an animal of this genus from Palinut Fontein, South Africa, sent to the Museum by Mr. Thomas Bain in May, 1878. The sjiecimen (Plate 12) gives more ample and exact evidence of the nature of Pareiasaurus than was previously available, and renders a re-examination of its affinities convenient. I have undertaken this description in the belief that the structures of Pareiasaurus throw more light upon the evolution of the Reptilia than any fossil that has been described. And I would express my thanks to Dr. Henry Woodward, F.R.S., Keeper of the Geological Department, for the facilities afforded me in making this examination. The Head. (Plates 13-16.) The skull has the general contours of the head of a Frog, being broad]y rounded in front, with the alveolar and jugal margins diverging posteriorly so as to form about two-thirds of an ellipse. The occipital border is transverse, and not evenly truncated. The upper surface of the head is flat, and the moderately deep post-orbital regions are obliquely inclined, so as to look outward and upward. The post-malar bones descend over the lower jaw in broader stronger processes than are seen in Rhyncho- saurus, but differently shaped from those seen in Edentates. The head is widest over the inferior extremities of these processes, where the width is about equal to the length, which measures 45 centims. The superficial bones, especially of the cheeks and upper part of the head, are sculptured with a pattern which combines radiating grooves of a Labyrinthodont type with Crocodilian pitting. In structure the skull, examined from above, is essentially Labyrinthodont ; but, seen from the palatal aspect, it is altogether Dicynodont. The dentition is distinctive, but on the whole makes a close approximation to that of Dinosaurs. The right side of the head is in less perfect preservation than the left side, especially along the roof-bones, but the specimen has suffered no distortion. * ‘ Geol. Soc. Quart. Journ.,’ vol. 32, 1876, p. 45. f ‘ Descriptive and Illustrated Catalogue of the Fossil Reptilia of South Africa,’ &c., 1876, p. 10.