Achillobator, Segnosaurus and Talarurus during the Bayan Shireh Formation of China.. Fauna of the Bayan Shireh Formation of China in what is now the eastern Gobi Desert. About 95-90 million years ago this area was lush and warm with floodplains and river systems. Achillobator is among the largest of Dromaeosaurs. Segnosaurus was a large Theriznosaur in the region and Talarurus an early Ankylosaurid.