Notice of new reptiles from the Laramie formation / by O.C. Marsh.

  • Marsh, Othniel Charles, 1831-1899.
Date:
[1892]
Catalogue details

Licence: Public Domain Mark

Credit: Notice of new reptiles from the Laramie formation / by O.C. Marsh. 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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    hitherto amon^,^ J3inosaurs, only in the genus Oeratosaurus dosenbecl by the writer from the Jurassic of Wyominj?.* The present pelvis resembles that of Ceratosauruis in its general features, but there is no foramen in the pubis. There are live vertebnx^ in the sacrum, firmly coossified with each other, as are also the sacral spines.- The saci-al vertebrjc are grooved below, with the sides of the centra excavated. The caudals have the diplosphenal articulation, and the first caudal bears a chevron. All the bones preserved are very delicate, and some of them, at least, are apparently pneumatic. The sacrum measures fifteen inches in length, and the twelve caudals following occupy a space of thirty-one inches. The known remains indicate a reptile about eight or ten feet in length. In the same horizon occur the remains of a very minute species, which agrees in all its characters, so far as determined, with the members of this genus. The most characteristic portions secured are the metatarsal bones, and these show the same features exhibited in the type species of the genus, 0. velox. They are, however, so much smaller as to suggest that they may pertain to a bird. Various portions of the second, third, and fourth metatarsals are known, and the distinctive feature is seen in the third, which has the upper part of the shaft so attenuated that it may not reach to the tarsus. The second and fourth metatarsals are very long and slender. This unique fossil, when alive, was about the size of the common fowl. The, species may be called OrniiJiomimxis ininutus. The large species described by the writer as Ornithomimiis gi'cvrtdis belongs in essentially the same horizon. Portions of two other skeletons have since been obtained, which apparently pertain to this species. In one of these, the femur, tibia, and fibula are in good preservation, and they clearly demonstrate that this reptile was one of the largest of the Therojyoda. The femur and tibia have each a very large cavity in the shaft, with well-defined -walls. Even the fibula has a cavity in its upper portion. In the other specimen, the second metatarsal is in fair preservation, and shows the same form as in the type of the genus. There is much probability that this gigantic carnivore was one of the enemies of the Geratopsidm, and the discovery of the entire skull and skeleton will be awaited with interest, as they will doubtless show special features for offense, which the peculiar defensive armor of the Ceratopsidm was designed to meet. The known remains of all the above species are from the Ceratops beds of Wyoming.