Gobi Desert of Inner Mongolia turns up evidence of a 90-million-year-old grave­yard

An expedition in the Gobi Desert of Inner Mongolia turns up evidence of a 90-million-year-old grave­yard, including the remains of more than a dozen fossilized ostrich like dinosaurs.
 

Evidence at the site points to a unique and rare conclusion: the dinosaur fossils were not deposited at the site over millennia. Instead the dinosaurs all met their fate at the same time.

The sudden death of the herd in a mud trap provides a rare snapshot of social behavior. Composed entirely of juveniles of a single species of ornithomimid dinosaur (Sinornithomimus dongi), the herd suggests that immature individuals were left to fend for themselves when adults were preoccupied with nesting or brooding.