Ichythosaurs, the dolphin-shaped, marine-dwelling reptiles of the Mesozoic Era, shared the Mesozoic seas with other reptile predators, like mosasaurs and plesiosaurs, but the discovery of a 10-meter long ichthyosaur from 240 million year old rocks in Nevada lays claim to top carnivore in Early Mesozoic marine ecosystems.
The Nevada ichythosaur has serrated teeth, previously unknown in ichythosaurs from this age. Other ichythosaurs of this time had conical teeth fit for grabbing fish and swallowing them whole, or blunt teeth suited for crushing shelly invertebrates like ammonites.
Later ichthyosaurs had serrated teeth, but did not reach the size of the Nevada specimen. This new find indicates that ichythosaurs were ecologically more diverse early in their evolutionary history than previously suspected.
Source: Nadia Frobisch, September 23, 2010, Society of Vertebrate Paleontology meeting.
Illustration from : http://www.marshalls-art.com/images/ipaleo/paleopg17/Ichthyosaurs_final.jpg
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