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

作者：Fischer Valentin^*; Arkhangelsky Maxim S; Uspensky Gleb N; Stenshin Ilya M; Godefroit Pascal

来源：Geological Magazine, 2014, 151(1): 60-70.

DOI：10.1017/S0016756812000994

• Ophthalmosauridae
• Aptian
• Ulyanovsk
• vision
• ecology

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.

• 出版日期2014-1