Champsosaurs were reptiles that lived during the Late Cretaceous Turonian time (90 mya) and into early Eocene time (56 mya). Thus, they lived during the time of some large dinosaurs. Also, they were the largest vertebrate to have survived the extinction crisis at the end of the Cretaceous Period. They occupied freshwater (rivers and swamps) and possibly estuaries. They resembled gharials (with their long narrow snouts used for catching fish) and, to a lesser degree, they resembled alligators. Nevertheless, they are not regarded as belonging to neither one of those two groups.
Figure 1. Two views (left side and dorsal) of Champsosaurus laramiensis.
Champsosaurs were up to 3 m in body length, and their bodies were streamlined, flattish, and covered in small scales. Their eyes were on top of the their head, and their ears were on the underside. Individuals had sexual dimorphism. The females had limb bones for land use, whereas the males were likely fully aquatic.
Ten species of champsosaurs have been named (whether or not all of these names are valid needs investigation). Champsosaurs lived in both freshwaters and salt waters, at the western edge of the Western Interior Seaway in coastal south-central Canada and north-central western USA. Also, a few early Cenozoic species are known from Belgium and northern France.
Classification
Kingdom Animali
Phylum Chordata
Class Reptilia
Order Choristodera
Genus Champsosaurus; [note: this word is derived from an ancient Greek source].
Type Species C. annectens Cope (nomen dubium)
Figure 2. Champsosaur sketch.
Figure 3. Gharial sketch---for comparative purposes.
Figure 4. Alligator sketch---for comparative purposes.
References Consulted
Abdale, J.R. 2020. Champsosaurus: The Croc-Lizard of the Cretaceous. https://dinosaursandbarbarians.com
Brown, B. 1905. The osteology of Champsosaurus Cope. Memoirs of the American Museum of Natural History, v. 9, pt. 1, 26 pp, 5 pls. [see digitallibrary.amnh.org]
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