Leninia

• Ulyanovsk Oblast, Russia

Leninia Stellan is a type of ichthyosaur from the family of Ophthalmosaurinae. So far, an incomplete skull from the Lower Cretaceous (Lower Albian ) is only known to the Russian Ulyanovsk Oblast comes.

Characteristics and lifestyle

Like other ichthyosaurs to Leninia recorded probably by a dolphin -like body, a long snout and large eyes in proportion. Tradition has it, the rear portion of the skull; the majority of the snout is missing. The fossil is preserved in three dimensions, the skull bones are still in their anatomical network. Teeth are not preserved in the resulting nose section; Leninia was probably either toothless or had a greatly reduced dentition. In the left eye socket, a complete and non- suppressed scleral ring is obtained. These bone reinforcement of the eye consists of 14 interlocking arranged to form a ring trapezoid bones. The scleral ring shows a diameter of about 18 centimeters - that he is in the order of Ophthalmosaurus and today's giant squid, the animals with the largest known eyes. The large eyes suggest that Leninia hunted in deep water at low light intensity.

Systematics and significance

Ichthyosaurs occupied a wide range of different ecological niches. Only a few representatives show adaptations to hunting in deep water - the most famous is the genus Ophthalmosaurus. Ophthalmosaurus was often regarded as highly specialized exception. Today, various close relatives of Ophthalmosaurus are known which show the same specialized adaptations; together with Ophthalmosaurus they are summarized as Ophthalmosaurinae. Leninia one of the last representatives of this group shows that the Ophthalmosaurinae during their long evolutionary history from the Middle Jurassic to the end of the Cretaceous hardly changed.

Fund and naming

The fossil was discovered southeast of the village Kriuschi on the right bank of the Volga. It was found within a loosely encountered Kalkkonkretion, but probably comes from a particular local rock layer which can be based on their ammonite fauna assigned to the Lower Albian.

The name Leninia refers to the Lenin memorial- and school complex in Ulyanovsk ( the birthplace of Lenin ), where the museum is located, which houses the fossil. The second part of the species name, Stellan, refers to the suture between the frontal and parietal bone, which appears in a star pattern Leninia.