Additional evidence as to the dentition and structure of the skull in the South African fossil reptile genus Diademodon / by H.G. Seeley.

  • Harry Govier Seeley
Date:
1908
Catalogue details

Licence: In copyright

Credit: Additional evidence as to the dentition and structure of the skull in the South African fossil reptile genus Diademodon / 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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    [From the Proceedings of the Zoological Society of London, 1908.J [Published October 1908.] Additional Evidence as to the Dentition and Structure of the Skull in the South African Fossil Reptile Genus Diademodon. By II. G. Seeley, F.R.S., F.Z.S., King’s College, London. (Text-figure 130.) The genus Diademodon was founded on the molar teeth and imperfect middle portions of small skulls. Four species were figured in Phil. Trans. Royal Society, 1894, B, pi. 89, referred to 1). tetragonus, D. brachytiara, D. mastacus, and D. broivni. They were the most remarkable evidences of dentition of mammalian type in extinct reptiles which have been found in South Africa. There would have been grounds, had the remains been mammalian, for referring them to three genera ; and in the description of plate 89, figure 11 is described as the left maxillary region of Diademodon (or Gomphognathus) mastacus. And in the original description of D. broumi (l. c. p. 1039) it is observed, “it is probably the type of a distinct genus.” Later in the same year the group Gomphodontia was defined as comprising animals with a Theriodont type of dentition, in which the molar teeth are expanded transversely, and as having more or less tuberculate crowns, of the type shown in Diademodon. In that group the genus Diademodon was included (l. c. 1895, B, p. 3). The types of Gomphognathus had the crowns of the molar teeth well worn, but the elevation of the external cusps or ridge in G. polyphagus made a suggestive resemblance to Diademodon mastacus; while the condition of the single well-preserved crown in Diademodon browni makes an equally suggestive approximation to Diademodon brachytiara. In 1896, in a short communication to the British Association at Liverpool, I briefly noticed another skull discovered by Dr. D. R. Kannemeyer. I have removed the matrix in the laboratory of King’s College, so as to demonstrate the sutures in the middle part of the skull and to expose the palate. The specimen is slightly squeezed so as to have a lateral obliquity towards the light side, from which the similar example of Diademodon broivni is not free. There is a coincidence in the anterior and posterior fractures being in identical positions in both specimens, favouring comparison. They are closely related species, but the snout in the new example is narrower and rather smaller, and the dentition being unworn favours the idea of specific difference, though the forms of the transversely ovate sections of the molar and premolar teeth are almost identical. As preserved the specimen is 2| inches long. It extends between an anterior transverse fracture through the two concave pits on the snout, which lie at the junction of the maxillary and nasal bones, which in Gomphognathus are situated midway between the orbits of the eyes and anterior nares, and a posterior fracture [1J