The type locality belongs to the Blackstone Formation (Ipswich Coal Measures Group) and is dated to the Carnian age (228.0 - 216.5 million years ago) of the Triassic period.
Carnian |
The type species of Ansunsaurus, A. huangguoshuensis, was named in 1999 from the Ladinian or Carnian age Falang Formation in Guanling County.
The fossils came from a mudstone next to a river channel deposit, in Lithofacies Association II of the Deep River basin, part of the extensive Newark Supergroup, dated as pertaining to either the late Carnian or early Norian faunal stages of the Late Triassic.
It was collected in the Otis Chalk Quarry 2 (TMM 31099 locality) from the Colorado City Formation, Chinle Group, dating to the early Carnian stage of the Late Triassic, about 228-227.5 million years ago.