The Middle-Late Jurassic transition period is a critical period for the evolution
of terrestrial vertebrates, but the global fossil record from this time is relatively
poor. The Shishugou Fauna of this period has recently produced significant fossil
remains of dinosaurs and other vertebrate groups, some representing the earliest known
members of several dinosaurian groups and other vertebrate groups and some representing
the best-known specimens of their group. These discoveries are significant for our
understanding of the origin and evolution of several vertebrate lineages. Radiometric
dating indicates that the fauna is aged approximately 159-164 Ma. Comparisons with
other similarly-aged terrestrial faunas such as Shaximiao and Yanliao show both taxonomic
similarities and differences between these faunas and indicate that the Junggar deposits
might have preserved the most complete vertebrate fossil record for a Middle-Late
Jurassic Laurasian terrestrial fauna.
