Petrolia Formation

Petrolia Formation
Petrolia Formation
Stratigraphic range: Permian
	Outcrops of the Petrolia Formation
Type	Formation
Unit of	Wichita Group
Underlies	Waggoner Ranch Formation
Overlies	Nocona Formation
Location
Region	Texas
Country	United States

The Petrolia Formation is a geologic formation in Texas. It preserves fossils dating back to the Permian period.

Paleontology

The Petrolia Formation has provided a rich vertebrate fauna. Many fossils were originally assigned to the Belle Plains Formation, although this formation is now considered synonymous with the Petrolia Formation. It is regarded as Early Leonardian in age based on ammonite biostratigraphy. Tit Mountain was once regarded as part of the now defunct Belle Plains Formation.

Synapsids of the Petrolia Formation
Genus	Localities	Species
Dimetrodon	Tit Mountain Tit Mountain	D.natalis D.limbatus	A small species of Dimetrodon. Large species of Dimetrodon.
Secodontosaurus	Tit Mountain	S. obtusidens	A sphenacodontid.
Ophiacodon	Tit Mountain	O.retroversus	An ophiacodontid.
Edaphosaurus	Tit Mountain	E.cruciger	An edaphosaurid.
Eothyris	Tit Mountain	E.parkeyi	A primitive synapsid.
Varanosaurus	Tit Mountain	V.wichitaensis	A varanopid.
Lupeosaurus	Tit Mountain	L. kayi	An edaphosaurid.
Ctenospondylus		C. casei	A sphenacodontid.

Chondricthyes

Cartilaginous Fish of the Petrolia Formation
Genus	Species	Notes
Orthacanthus	O.platypternus	A xenacanthid.
Barbclabornia	B.luederensis	A giant xencanth.

Amphibia

Amphibians of the Petrolia Formation
Genus	Species	Notes
Zatrachys	Z.sp	A temnospondyl.
Archeria	A.sp.	An embolomere.
Trimerorhachis	T.bilobatus	A dvinosaur.
Eryops	E.sp.	A temnospondyl.
Parioxys	P. sp.	A temnospondyl.

Reptiliomorpha

Reptiliomorphs of the Petrolia Formation
Genus	Species	Notes
Diadectes	D.sp.	A diadectid.

References

1 2 3 Iii, Nicholas Hotton; Feldmann, Rodney M.; Hook, Robert W.; Dimichele, William A. (2002). "Crustacean-bearing continental deposits in the Petrolia Formation (Leonardian Series, Lower Permian) of north-central Texas". Journal of Paleontology. 76 (3): 486–494. doi:10.1666/0022-3360(2002)076<0486:CBCDIT>2.0.CO;2. ISSN 0022-3360.
↑ Olson, Everett (1955). "FAUNA OF THE VALE AND CHOZA" (PDF). Internet Archive.
1 2 3 4 5 6 7 8 9 Brocklehurst, Neil (2015-11-06). "The early evolution of Synapsida (Vertebrata, Amniota) and the quality of their fossil record". Humboldt University: 300–303. doi:10.18452/17351.
1 2 Johnson, Gary (2005). "UNDERDEVELOPED AND UNUSUAL XENACANTH SHARK TEETH FROM THE LOWER PERMIAN OF TEXAS" (PDF). Scispace.
1 2 3 4 5 "Tit Mountain, 21". Paleobiology database. 2026.

Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Archived from the original on 25 March 2022. Retrieved 17 December 2021.

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[:0-1] 1 2 3 Iii, Nicholas Hotton; Feldmann, Rodney M.; Hook, Robert W.; Dimichele, William A. (2002). "Crustacean-bearing continental deposits in the Petrolia Formation (Leonardian Series, Lower Permian) of north-central Texas". Journal of Paleontology. 76 (3): 486–494. doi:10.1666/0022-3360(2002)076<0486:CBCDIT>2.0.CO;2. ISSN 0022-3360.

[2] Olson, Everett (1955). "FAUNA OF THE VALE AND CHOZA" (PDF). Internet Archive.

[:1-3] 1 2 3 4 5 6 7 8 9 Brocklehurst, Neil (2015-11-06). "The early evolution of Synapsida (Vertebrata, Amniota) and the quality of their fossil record". Humboldt University: 300–303. doi:10.18452/17351.

[:2-4] 1 2 Johnson, Gary (2005). "UNDERDEVELOPED AND UNUSUAL XENACANTH SHARK TEETH FROM THE LOWER PERMIAN OF TEXAS" (PDF). Scispace.

[:3-5] 1 2 3 4 5 "Tit Mountain, 21". Paleobiology database. 2026.