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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    inff Mammalia. All three have certain points of resemblance, but differ widely in other respects. Their exact relations to each other and to other mammals are still uncertain, but future discoveries may at any time olear the matter up. One fact is becoming more and more evident, the near affinity of the early Primates, Carnivores, Ungulates, and Rodents, with each other and with the Insectivores, and more remotely with Marsupials. The key to the mystery lies con- cealed in the great break between the lower Wahsatch, at the base of the Eocene as now known, and the Laramie beds of the Cre- taceous. In the latter, none of the above placental mammals have been found, but in the early Eocene occur, side by side, Carnivores, Rodents, and Ungulates, the last represented by both typical Perissodactyles and Artiodactyles, and even some of their subdivisions. The AmUydactyia of large size, the Tillodontia also large, and the diminutive Mesodactyla, all apparently lived together in this period, and a comparison of their special characters points out their probable lines of descent. The convergence of these lines makes every discovery in the earlier geological horizons of importance, and a connection with the Mesozoic Mammalia may at any moment be demon- strated. The Edentates are evidently a later development, as are also the Sirenians and Cetaceans. New Haven, Conn.. April 16, 1892. Notice of New Reptiles from the Laramie Formation', by O. C. Marsh. Among the extensive collections of vertebrate fossils secured during the last few years from the Ceratops beds along the eastern base of the Rocky Mountains, remains of reptiles largely predominate, and many have already been described by the writer. A number of new forms of much interest have recently been secured, and some of these are briefly noticed below. The presence of Ophidians and true Lacertilians among the gigantic forms of Dinosauria is especially note- worthy, as their discovery has long been expected. The new Dinosaurs described confirm previous indications, that this subclass, before its extinction, developed into many highly specialized forms, of which suggestions, at least, were seen in those from lower horizons. The large number and variety of these specialized forms could hardly have been anticipated, and they make prominent the probability that the Reptilian age reached its culmination near the close'of the Cretaceous.