Popo Agie Formation

The Popo Agie Formation (/poʊˈpoʊʒə/ poh-POH-zhə)^[1][2] is a Triassic geologic formation that crops out in western Wyoming, western Colorado, and Utah. 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.^[3] The earliest known dinosaur of the Laurasian continent, Ahvaytum, is discovered from the Popo Agie Formation. Dinosaurian trace fossils and fragmentary fossils of prehistoric reptiles and amphibians, including pseudosuchian reptiles and temnospondyl amphibians, have also been reported from this formation.^[4]

Popo Agie Formation
Stratigraphic range: Late Triassic Carnian PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Unit of	Chugwater Group
Overlies	Gartra Formation
Location
Region	North America
Country	United States

Paleobiota

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Amphibians

Taxon	Member	Material	Notes	Images
Apachesaurus sp.		Complete skull	A metoposaurid temnospondyl; specimen from the Popo Agie Formation was originally described as Anaschisma sp. and later Eupelor browni[5]
Anaschisma browni		Complete skull	A metoposaurid temnospondyl.[6]
Metoposauridae indet.		Complete skull	Specimen was originally described as Anaschisma browni[5]

Reptiles

Taxon	Species	Member	Material	Notes	Images
Ahvaytum[4]	A. bahndooiveche		UWGM 1975, a left astragalus, and UWGM 7549, a partial left femur	A probable sauropodomorph dinosaur and the oldest known Laurasian dinosaur
Heptasuchus	H. clarki		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	B. cooowuse		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. Hyperodapedon sanjuanensis	(in foreground)
Poposaurus	P. gracilis		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]
Sulcimentisauria indet.[4]	Indeterminate		A partial left humerus and right femur	A 'silesaurid'

Synapsids

Taxon	Member	Material	Notes	Images
Eubrachiosaurus browni		FMNH UC 633, a partial left scapula, left humerus, and left pelvis from Lander, Wyoming	A dicynodont[12]

See also

• Earth sciences portal
• Paleontology portal
• Dinosaurs portal

• List of dinosaur-bearing rock formations
  • List of stratigraphic units with indeterminate dinosaur fossils