Ferganasaurus verzilini, gen. et sp. nov., a new neosauropod (Dinosauria, Saurischia, Sauropoda) from the Middle Jurassic of Fergana Valley, Kirghizia

ABSTRACT

A partial sauropod skeleton from the Middle Jurassic (Callovian) Balabansai Formation in Kirghizia, comprising two dorsal and 16 caudal vertebrae, pelvis and limb bones is described and referred to Ferganasaurus verzilini, gen. et sp. nov. The manus is known only from drawings as original material has been lost; foot bones, except the astragalus, are unknown. Ferganasaurus forms an unresolved polytomy with neosauropods Jobaria, Diplodocoidea (Nemegtosauridae, Rebbachisauridae, Diplodocidae, and Dicraeosauridae), and Macronaria (Camarasaurus, Haplocan-thosaurus and Titanosauriformes). The neosauropod characters of Ferganasaurus include five coossified sacral vertebra, metacarpal proximal ends subtriangular, composite proximal articular surface of metacarpus U-shaped, tibia with sub-circular proximal end, astragalar ascending process extends to the posterior margin of the astragalus, and astragalus wedge-shaped in anterior view. Ferganasaurus is one of the oldest known neosauropods, and possesses two primitive characters unusual for a neosauropod (femur shaft with sigmoid curve, and fourth trochanter of the femur blade-like with acuminate apex).