Caudal vertebrae of titanosaurian sauropod dinosaurs from the Lower Cretaceous Ilek Formation in Western Siberia, Russia

Three sauropod middle caudal vertebrae are described from the three different localities within the Lower Cretaceous (Barremian-Aptian) Ilek Formation in Krasnoyarsk Territory, Western Siberia, Russia. All vertebrae are strongly procoelous and can be referred to Lithostrotia indet. LMCCE 005/40 from Bol'shoi Kemchug 3 locality has a ventral groove on centrum and a very large neural spine that projects posteriorly far beyond the centrum. This specimen also lacks postzygapophyses and bears a heavily sculptured neural spine suggesting high degree of development of the interosseous ligaments. The structure of the neural spine LMCCE 005/40 is similar to that of the saltasaurine Neuquensaurus from the Late Cretaceous of South America. However, the Siberian specimen lacks camellate bone texture characteristic for the caudal vertebrae of Saltasaurinae and its similarity with Neuquensaurus in development of the neural spine likely was independently acquired. These new findings increase the known diversity of sauropod dinosaurs in the Early Cretaceous of Siberia, which includes three taxa of Lithostrotia indet. described herein, lithostrotian Tengrisaurus, and titanosauriform Sibirotitan. (C) 2019 Elsevier Ltd. All rights reserved.