On the affinities of the Stereognathus ooliticus (Charlesworth) : a mammal from the oolitic slate of Stonesfield / by Professor Owen.

  • Owen, Richard, Sir, 1804-1892.
Date:
1857
Catalogue details

Licence: Public Domain Mark

Credit: On the affinities of the Stereognathus ooliticus (Charlesworth) : a mammal from the oolitic slate of Stonesfield / by Professor Owen. 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.

    4/14 (page 4)
    three cusps, as in the Stereognathus; but the middle pair of cusps in the Hyracotherium are very small, appearing, in fact, as mere conical tubercular elevations of the middle of the ridge connecting the fore part of the base of the outer and inner principal cones. In the Hyopotamus and Anthracotherium*, the intermediate cone between the outer and inner principal cones of the anterior half of the molar tooth is developed to equality of size with them, and three cusps or cones are thus seen on the same transverse line of the crown. But there is no trace of the middle cone or tubercle (like that seen in fig. 5, i, between the outer, o', and inner, p', hinder cones), an- swering to the rudimental cusp in Hyracotherium and to the cone i in Stereognathus. In the little Microtherium or Cainotherium of the miocene de- posits of Germany and France the middle lobe or cone is developed between the pair at the back part of the upper molar, answering to cone i in fig. 5 ; but the cone answering to h, fig. 5, is not developed between the front pair of cones. This tendency, however, to lobes, cones, or cusps, in threes, in the older tertiary Mammals, is very significant evidence, as it* seems to me, of the affinities of the small oolitic mammal having the above-described regular sex-cuspid molars. The molars of the lower jaw of the Hyopotamus and other An- thracotherioids show no trace of a lobe or cone intermediate between the outer and inner cones of each transverse pair. The structure of the lower molars of the Hyracotherium is unknown : it is most pro- bable, however, that the lower molars of the Chceropotamus would most resemble those of the Hyracothere; and in the penultimate and last grinders of the Chceropotamus a rudimental cusp appears between the outer and inner principal cusps. The proportional size, and regularity of form, of the cones of the grinding teeth of the Stereognathus give a quite different character of the crown from that of the multicuspid molars of the Insectivora, and cause it to resemble more the quadricuspid or pentecuspid molars of the Artiodactyle non -ruminant extinct genera above cited. I conclude, therefore, that, like the Bichobunes, Xiphodon, Mi- crotherium, Rhagatherium, Hyopotamus, and Hyracotherium, the Stereognathus ooliticus was a diminutive form of the great Ungu- late order of Mammalia, and that it most probably belonged to the artiodactyle or even-toed division of that order, and to the non-rumi- nant section of that division, the food of which, if we may judge from the existing hogs and peccaries, was of a mixed nature. The interest which the above-described fossil from the Stonesfield oolitic slate excites is not exclusively due to its antiquity, its unique- ness, or its peculiarity : much arises out of its relations as a test, in the present state of Palaeontology, of the actual value of a single tooth in the determination of the rest of the organization of an animal, or of so much of it as serves for a recognition of the place of the ex- tinct species in the zoological series: the attempt, at least, to ana- lyse the mental processes by which one aims at the restoration of * Quart. Journ. Geol. Soc. vol. iv. pi. 7. figs. 1, 6, & 9.