The holotype, IGM 100/84, was collected in the Bayan Shireh Formation (=Baynshirenskaya) in Khara Khutul, southeastern Mongolia, dating from the Cenomanian and the Turonian stages, around 98-89.3 million years ago. It was first reported in 1979.[1] It consists of a partial skeleton, lacking the skull, which includes a nearly complete pelvis with part of the right ischium missing.