On the Order Theriodontia, with a Description of a new Genus and Species ( Ælurosaurus Felinus, Ow.)

Abstract

Of Permian and Triassic Reptilia the most interesting, those that help to fill the hiatus separating the mammalian Marsupials from the cold-blooded Vertebrates, seem to me to be the extinct species constituting, or referable to, the Order Theriodontia . To the characters of this Order given in my ‘Catalogue of the Fossil Reptilia of South Africa’†, viz. “Dentition of the Carnivorous type, incisors defined by position and divided from molars by a large laniariform canine on each side of both upper and lower jaws,” may now be added “dentition ‘monophyodont’”‡. At least I have not had evidence of an immature specimen showing a milk-series of teeth to be succeeded by a permanent series; but if such should be found in any of the extinct Reptiles of the present Order, such Order will be “Diphyodont,” like the Mammalian Carnivora; for there is no evidence of any third set of teeth to follow those which may have been preceded (though I doubt it) by a first or deciduous set. Of the adult dentition, whether it be “first” or “second,” the molars, as a rule, are inferior in size to the incisors, as both are markedly less than the canines. Add to these characters, “humerus perforated by an entepicondylar foramen”§. The Reptiles sodistinguished or characterized are already referable to several genera; and although I fully recognize the artificial character of a more or less forward extension of the ossified ‘septum narium,’ there was a convenience in disparting the Theriodont genera known in 1876 into