Popo Agie Formation


The Popo Agie Formation is a Triassic geologic formation that outcrops in western Wyoming, western Colorado, and Utah. It was deposited during the Late Triassic in fluvial and lacustrine environments that existed across much of what is now the American southwest. Fragmentary fossils of prehistoric reptiles and amphibians, including pseudosuchian reptiles and temnospondyl amphibians, have been discovered in the Popo Agie Formation. Dinosaur remains are also among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus.

Paleobiota

Amphibians

TaxonMemberMaterialNotesImages

Apachesaurus sp.
Complete skull
A metoposaurid temnospondyl; specimen from the Popo Agie Formation was originally described as Anaschisma sp. and later Eupelor browni

Koskinonodon perfecta
Complete skull
A metoposaurid temnospondyl; specimen from the Popo Agie Formation was originally described as Borborophagus wyomingensis

Metoposauridae indet.
Complete skull
Specimen was originally described as Anaschisma browni

Reptiles

TaxonMemberMaterialNotesImages

Heptasuchus clarki
UW 11562, a partial skull and postcranial skeleton; UW 11563 through UW 11565, partial postcranial remains; both from Big Horn Mountains, Wyoming
A rauisuchian

Hyperodapedon cf. H. sanjuanensis
USNM 494329, a left maxilla and premaxilla from Willow Creek, Wyoming
A rhynchosaur

Poposaurus gracilis
UR 358, a partial ilium from Lander, Wyoming; UR 357, a partial skeleton including vertebrae, hips, and limb bones
A bipedal poposauroid first described from the Popo Agie Formation and known from more complete specimens from the Chinle Formation

Synapsids

TaxonMemberMaterialNotesImages

Eubrachiosaurus browni
FMNH UC 633, a partial left scapula, left humerus, and left pelvis from Lander, Wyoming
One of only two dicynodonts known to have lived in the northern hemisphere during the Late Triassic, the other being Placerias from the Chinle Formation

Footnotes