What are ichthyosaurs?

ichthyosaurs, whose name means "fish lizard" in Greek, were large naval reptiles who lived between 230 and 90 million years. They were superficially similar to fish or dolphins. Ichthyosaurs shared a sea of ​​land with sharks, fish and other sea plas, such as Plesouurs and Pliosaurs. Ichthyosaurs were first described from fossil fragments dug in 1699 in Wales.

ichthyosaurs developed only 21 million years after the largest mass extinction in history and disappeared about 25 million years before the mass extinction killed by dinosaurs. Although the ichthyosaurs are sometimes incorrectly called dinosaurs, they were not. The structure of a body similar to ichthyosaur fish led biologist Stephen Jay Goulda to call them his favorite example of parallel development. Not so much flies as a small tail fin. The earliest ichthyosaurs were small (about a meter in length) and lacked long fins of later ichthyosaurs, instead swimming with a wavy movement of a similar eel.

Most ichthyosaurs were about 2 to 4 m (6.6 to 13.2 ft), with a head -like head, long snout and sharp teeth. Some reached a length of 55 ft (17 m), such as Shonisaurus , state fossils Nevada, although it was very large and much less typical. The largest was Shonisaurus sikanniensis , the largest known sea reptile at 21 m (69 ft). The largest ichthyosaurs died out at the end of the Triassical period.

Most ichthyosaurs had large, convex eyes. They ate meat, especially fish and occasional seafood or youthful sea reptile. Heydey of Ichthyosaurs was in trias and evolved at about the same time the dinosaurs did. Potriassic and morning Jurassic, their diversity went downhill and half of Jurassic all ichthyosaurs were one of the only ones. The ithyosaurs then disappeared into chalk, one of the only main groups that died out in itself and not because of mass extinction at the end of the period.