It was deposited during the Late Triassic in fluvial (river) and lacustrine (lake) environments that existed across much of what is now the American southwest.
Complete skull A metoposaurid temnospondyl; specimen from the Popo Agie Formation was originally described as Anaschisma sp.
Complete skull Specimen was originally described as Anaschisma browni[5] Ahvaytum[4] UWGM 1975, a left astragalus, and UWGM 7549, a partial left femur A probable sauropodomorph dinosaur and the oldest known Laurasian dinosaur Heptasuchus UW 11562, a partial skull and postcranial skeleton; UW 11563 through UW 11565, partial postcranial remains; both from Big Horn Mountains, Wyoming[7] A rauisuchian
(in background) Beesiiwo USNM 494329, a left maxilla and left dentary from Hole in the Wall, Wyoming; TxVP 46037.1, UWGM 7027 and UWGM 7028, maxillary fragments from Cottonwood Creek, Wyoming[8] A rhynchosaur, previously assigned to cf.
(in foreground) Poposaurus UR 358, a partial ilium from Lander, Wyoming;[9] UR 357, a partial skeleton including vertebrae, hips, and limb bones[10] A bipedal poposauroid first described from the Popo Agie Formation and known from more complete specimens from the Chinle Formation[11]