Ischyrotherium Explained

Ischyrotherium is an extinct genus named by Joseph Leidy in 1856 for fossils from the lignite deposits in Nebraska. Originally considered an herbivorous cetacean, Leidy then reassigned it to Sirenia as a relative of manatees, before Edward Drinker Cope reclassified it as a non-mammalian, suggesting the new name Ischyrosaurus to better identify its reptilian origins, as he considered it a sauropterygian.^{[1] [2] [3]} Ischyrotherium was found alongside material from the hadrosaur Thespesius and turtles Compsemys and Emys, and the fish Mylognathus.^[2] The name Ischyrosaurus was also used by John Whitaker Hulke for the sauropod now known as Ornithopsis manseli, as he was unaware it was preoccupied by Cope.^[4]

Notes and References

1. Leidy. J.. 1856. Notice of extinct Vertebrata, discovered by F. V. Hayden during the expedition to the Sioux country under the command of Lieut. G.K. Warren. Proceedings of the Academy of Natural Sciences of Philadelphia. 8. 89.
2. Leidy. J.. 1860. Extinct Vertebrata from the Judith River and Great Lignite Formations of Nebraska. Transactions of the American Philosophical Society . New Series. 11. 139–154. 10.2307/3231936. 3231936.
3. Cope. E.D.. 1869. Synopsis of the extinct Batrachia, Reptilia, and Aves of the United States. Transactions of the American Philosophical Society. 14. 1–252. 10.2307/1005355. 1005355.
4. Book: Martill. D.M.. Earland. S.. Naish. D.. 2006. Dinosaurs in marine strata: evidence from the British Jurassic, including a review of the allochthonous vertebrate assemblage from the marine Kimmeridge Clay Formation (Upper Jurassic) of Great Britain. ColectivoArqueológico-Paleontológico Salense. Actas de las III Jornadas sobre Dinosaurios y su Entorno. 1–31.