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A new Lower Cretaceous ichthyosaur from Russia reveals skull shape conservatism within Ophthalmosaurinae

Published online by Cambridge University Press:  01 March 2013

Geology Department, University of Liège, B-18, Allée du 6 Août, 4000 Liège, Belgium Palaeontology Department, Royal Belgian Institute of Natural Sciences, 29, Rue Vautier, 1000 Brussels, Belgium
Ecology Department, Geological Faculty, Saratov State University, Ulitsa Astrakhanskaya, 83, 410012, Saratov, Russia
Natural Science Museum, Ulyanovsk State University, Ulitsa L.Tolstogo, 42, 424320 Ulyanovsk, Russia
Ulyanovsk Regional Museum of Local Lore named after I. A. Goncharov, 3/4, Prospekt Novy Venetz, 432601, Ulyanovsk, Russia
Palaeontology Department, Royal Belgian Institute of Natural Sciences, 29, Rue Vautier, 1000 Brussels, Belgium
Author for correspondence:


Ophthalmosaurinae is a recently recognized clade of derived ichthyosaurs (marine reptiles) ranging from the Bajocian (Middle Jurassic) to the late Albian (late Early Cretaceous). Whereas the Middle–Late Jurassic ophthalmosaurine Ophthalmosaurus is often regarded as a hyperspecialized deep diver, very little is known about the anatomy, evolutionary history and ecology of Cretaceous ophthalmosaurines because of the scarcity of the fossils and the lack of well-preserved skull material. Here, we describe the skull of a new basal ophthalmosaurine ichthyosaur, Leninia stellans gen. et sp. nov., from the lower Aptian of western Russia, and compare the ocular characteristics of ophthalmosaurids. Leninia is recovered as a basal ophthalmosaurine; it possesses unique traits such as a star-shaped frontal–parietal suture as well as features previously thought to be unique to Ophthalmosaurus such as a supratemporal–stapes contact. A large sclerotic aperture – significantly larger than in platypterygiine ophthalmosaurids and similar to that of the largest-eyed modern animals (giant and colossal squids) – and reduced dentition appear widespread within ophthalmosaurines. This conservatism suggests ophthalmosaurine ophthalmosaurids occupied similar ecological niche(s) throughout their long evolutionary history.

Original Articles
Copyright © Cambridge University Press 2013 

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