Sauropods were a very successful group of dinosaurs during the Jurassic and
Cretaceous periods, but their earlier history is poorly known. Until now,
the earliest reported sauropod bones were from the Early Jurassic(1-3), and
the only tentative evidence of earlier sauropods was in the form of contro
versial footprints(4,5). Here we report the discovery of an incomplete saur
opod skeleton from the Late Triassic period of Thailand, which provides the
first osteological evidence of pre-Jurassic sauropods. This dinosaur is ma
rkedly different from prosauropods and substantiates theoretical prediction
s that there was a fairly long period of sauropod evolution during the Tria
ssic.