Page:Quarterly Journal of the Geological Society of London, vol. 35.djvu/198

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148
R. OWEN ON THE PURBECK
10. On the Association of Dwarf Crocodiles (Nannosuchus and Theriosuchus pusilliis, e.g.) with the Diminutive Mammals of the Purbeck Shales. By Professor Richard Owen, C.B., F.R.S., F.G.S., &c. (Read November 6, 1878.)

[Plate IX.]

Agreeably with an intimation at the close of the Monograph (No. VIII.) "On the Fossil Reptilia of the Wealden and Purbeck Formations," which appeared in the volume of the Palæontographical Society issued in 1878 (p. 15), I communicated to the Geological Society of London[1] a paper in which ideas suggested by the subjects of that Monograph on certain relations of Mesozoic and Neozoic Crocodilia to their prey were more fully detailed, and an instructive discussion was thereupon raised agreeably with the writer's design.

To his assumption that the mammalian prey of Neozoic Crocodiles were non-existent in Mesozoic times, an experienced palæontologist objected that such were in existence at those periods, and coexisted with the Teleosaurs and other amphicœlian Crocodiles[2].

It had not occurred to me that the mammalian prey of the Neozoic Crocodiles[3], which I had in view, and which were exemplified in my mind and meaning by the Tiger, the Buffalo, and similarly large unguiculate and ungulate species, could be represented or suggested by the extinct mammals from the Purbeck and Stonesfield strata, in the restoration of which, and the vindication of their claims to warm-blooded and mammiferous eminence, no small proportion of past palæontological work had been submitted by me in former days to the Geological Society[4].

Subsequent additions to our knowledge of Mesozoic mammals have not revealed any species approaching in size to the Ichneumons[5], which haunt the banks of the Nile, the Indus, or the Ganges. Such Viverrines are disdained by the large Crocodilia of these rivers; at least the vermiform mammals are not known to fall a prey to them, or to call for the exertions, emerged or submerged, which the subduing of the struggles of a tiger or buffalo require. On the contrary, the attitude of the Crocodile to the small mammal is reversed; the Ichneumon is the enemy and destroyer, in relation, at least, to

  1. February 6, 1878; Quart. Journ. Geol. Soc. vol. xxxiv. p. 421.
  2. "Mr. Hulke observed that with respect to Prof. Owen's idea that warm-blooded animals were not preyed on by the Mesosuchian Crocodiles, it could not be doubted that such did actually exist contemporaneously with them."—Quart. Journ. Geol. Soc. 1878, vol. xxxiv. p. 428.
  3. "Large species of warm-blooded mammals," tom. cit. p. 423. "The advent in Tertiary time of large mammalian quadrupeds browsing or prowling along the shores," &c. p. 426.
  4. Trans. of the Geol. Soc. 4to, 2nd series, vol. vi. p. 47, pl. 5; Proc. of Geol. Soc. 8vo, 1838, p. 17; Quart. Journ. Geol. Soc. vol. x. p. 426 (1854).
  5. Herpestes ichneumon, Cuv., 5 feet in length.