A new Middle Jurassic diplodocoid suggests an earlier dispersal and diversification of sauropod dinosaurs

Abstract

The fragmentation of the supercontinent Pangaea has been suggested to have had a profound impact on Mesozoic terrestrial vertebrate distributions. One current paradigm is that geographic isolation produced an endemic biota in East As ia during the Jurassic, while simultaneously preventing diplodocoid sauropod dinosaurs and seve ral other tetrapod groups from reaching this region. Here we report the discovery of the earliest diplodocoid, and the first from East Asia, to our knowledge, based on fossil material comprisi ng multiple individuals and most parts of the skeleton of an early Middle Jurassic dicraeosaurid. The new discovery challenges conventional biogeographical ideas, and suggests that dispersal into East Asia occurred much earlier than expected. Moreover, the age of this new taxon indicates that many advanced sauropod lineages originated at least 15 million years earlier than previously realized, achieving a global distribution while Pangaea was still a coherent landmass.