Elasmosaurus

Abstract: The type specimen of Elasmosaurus platyurus Cope, 1868 from the Upper Cretaceous (lower Campanian) of Kansas, U.S.A. is redescribed. It consists of part of the skull (e. g., both premaxillae, parts of the maxillae, the occipital condyle and parts of the dentaries), the almost complete vertebral column, including the atlas-axis complex, as well as the pectoral and pelvic girdles (although the latter are now lost). The genus Elasmosaurus can be defined by two unambiguous autapomorphies, the presence of six premaxillary teeth and the high number of 71 cervical vertebrae. It also exhibits a number of advanced features, which are discussed and compared with other elasmosaurs.

Abstract: The material here described includes 1.) A Plesiosaurian pubis (fig. 1) from the Lower Campanian at Onnestad, N. E. Scania. The bone is with great probability referable to Scanisaurus cf. nazarowi (Bogolubov 1911).— This specimen is the first known Reptile remnant from Onnestad. 2.) A Plesiosaurian humerus (fig. 2) from the Lower Campanian of the island of Ivo, N. E. Scania. 3.) An incomplete Plesiosaurian vertebral centrum, a fragment of another centrum, and a fragment of a limb bone, all from the Upper Campanian of Hanaskog, N. E. Scania. The limb bone fragment (fig. 3) is a part of the >shaft> of a very large propodial bone, possibly belonging to Elasmosaurus? cf. gigas (Schroder 1885).— Plesiosaurian remains are rare in the Upper Campanian of Scania, and the bones here mentioned are the first ones known from Hanaskog. 4.) Mosasaurian tooth crown from the Upper Campanian of Hanaskog. The specimen is provisionally referred to Leiodon sp. 5.) A Plesiosaurian vertebral centrum from the glacial dr...

Abstract: When E.D. Cope described the type specimen of Elasmosaurus platyurus 1868 more completely in 1869, he noted that a number of dorsal vertebrae were missing, along with the gastralia, the limbs, and most of the skull. Although the military surgeon who discovered the remains, Dr. Theophilus H. Turner, made additional searches the missing material was never located. Interest in the specimen eventually faded as dinosaurs were discovered further west, and portions of the specimen, including the pectoral and pelvic girdles, were mysteriously lost. More recently, three collections of associated plesiosaur material, including dorsal vertebrae, ribs, gastralia, and large gastroliths were made from a second site near the type locality of E. platyurus. The additional material is curated in the Sternberg Museum of Natural History, Hays, KS, the University of Kansas Museum of Natural History, Lawrence, KS, and the Cincinnati Museum Center, Cincinnati, OH. Examination the more recently discovered remains in these three repositories, and comparisons with the those of the type specimen at the Academy of Natural Sciences of Philadelphia, a review of the letters and other historical documents related to the discovery of E. platyurus, and on–site evaluation of the stratigraphy of the both localities suggest that the more recently collected remains were originally part of the type specimen and were separated prior to burial when the floating carcass began to fall apart. Contents