Cymbospondylus

Cymbospondylus (meaning "cupped vertebrae") is an extinct genus of large ichthyosaurs, of which it is among the oldest representatives, that lived during the Anisian stage of the Middle Triassic in what are now North America and Europe. The first known fossils of this taxon are a set of more or less complete vertebrae which were discovered in the 19th century in various mountain ranges of Nevada, in the United States, before being named and described by Joseph Leidy in 1868. It is in the beginning of the 20th century that more complete fossils were discovered through several expeditions launched by the University of California, and described in more detail by John Campbell Merriam in 1908, thus visualizing the overall anatomy of the animal. While many species have been assigned to the genus, only five are recognized as valid, the others being considered synonymous, doubtful or belonging to other genera. Cymbospondylus was formerly classified as a representative of the Shastasauridae, but more recent studies consider it to be more basal, view as the type genus of the Cymbospondylidae.

As an ichthyosaur, Cymbospondylus had flippers for limbs and a fin on the tail. Like other non-parvipelvian ichthyosaurs, Cymbospondylus has a very slender profile, unlike later ichthyosaurs which have a morphology similar to those of dolphins. The different species of Cymbospondylus vary greatly in size, with the smallest reaching around 4 to 5 metres (13 to 16 ft) in length. The largest known species, C. youngorum, is estimated over 17 metres (56 ft) long, making Cymbospondylus one of the largest ichthyosaurs identified to date, but also one of the largest animals known of its time. The animal has a skull with a long, thin snout, proportionally small eye sockets, an elongated trunk, and a less pronounced tail than in later ichthyosaurs. The teeth are conical and pointed, having longitudinal ridges, indicating a diet of fishes and cephalopods, and possibly other marine reptiles for larger species.