Additions to the Early Cretaceous dinosaur fauna of Transbaikalia, Eastern Russia

Abstract

Eight dinosaur taxa are currently known from the Early Cretaceous (Barremian-Aptian) Murtoi Formation in the Lake Gusinoe Depression of western Transbaikalia: the theropod Richardoestesia sp.* and indeterminate therizinosauroid, ornithomimosaur and dromaeosaurid material; a titanosauriforme sauropod (cf. Euhelopus), and cf. Mongolosaurus sp.; and an indeterminate ornithopod* and the ceratopsian Psittacosaurus sp. (taxa marked with an asterisk were not reported previously). In the more easterly Chikoi-Khilok Depression the Early Cretaceous (Aptian) Khilok Formation has produced fragmentary remains of four dinosaur taxa: the theropod ‘Prodeinodon’ sp. and an indeterminate dromaeosaurid, an indeterminate titanosauriform (cf. Nemegtosaurus) and an indeterminate ornithopod. The most notable differences between the two faunas are the absence of large carnivorous theropods in the Murtoi Formation and the different composition of the sauropod and, perhaps, the ornithopod faunas in each basin.