Popo Agie Formation

The Popo Agie Formation (/poʊˈpoʊʒə/ poh-POH-zhə) 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. 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.

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.
Taxon	Reclassified taxon	Taxon falsely reported as present	Dubious taxon or junior synonym	Ichnotaxon	Ootaxon	Morphotaxon

Amphibians

Taxon	Species	Material	Notes
Apachesaurus	A. sp.	Complete skull	A metoposaurid temnospondyl, originally described as Anaschisma sp. and later Eupelor browni
Anaschisma	A. browni	Complete skull	A metoposaurid temnospondyl
Metoposauridae	Indeterminate	Complete skull	Originally described as Anaschisma browni

Reptiles

Taxon	Species	Material	Notes	Images
Ahvaytum	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	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	A rhynchosaur, previously assigned to cf. Hyperodapedon sanjuanensis	(in foreground)
Poposaurus	P. 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
Sulcimentisauria indet.	Indeterminate	A partial left humerus and right femur	A 'silesaurid'

Synapsids

Taxon	Species	Member	Material	Notes	Images
Eubrachiosaurus	E. browni		FMNH UC 633, a partial left scapula, left humerus, and left pelvis from Lander, Wyoming	A dicynodont

Footnotes

Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. ISBN 0-520-24209-2.