Trinity Group (geologic group)

The Trinity Group is a group (sequence of rock strata) in the Lower Cretaceous lithostratigraphy of Texas, Arkansas, Mississippi, Louisiana and Oklahoma.^[2][3][4] It is named for the Trinity River of Texas.

Trinity Group
Stratigraphic range: late Aptian-early Albian, 115–106 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Group
Sub-units	Paluxy Formation Glen Rose Formation Twin Mountains Formation
Underlies	Fredericksburg sands, Goodland Formation
Overlies	Cotton Valley Formation
Location
Region	Texas, Arkansas
Country	United States
Type section
Named for	Trinity Rivers, Texas
Named by	Robert Thomas Hill^[1]

Trinity Group stratigraphic column in Texas

A stratigraphic column at the Mount Bonnell Fault location starts with the Lower Cretaceous Trinity Group overlain by the Edwards Group. Upper Cretaceous formations follow, starting with the Del Rio Clay, Buda Limestone, and then the Eagle Ford Group. Formations within the Trinity Group include the Hammett Formation, Cow Creek Formation, Hensel Formation, and Lower and Upper Glen Rose Formation. The Hammett and the lower portion of the Upper Glen Rose act as confining units (or aquitard) for the Middle Trinity Aquifer. The Upper Glen Rose contains the Upper Trinity Aquifer, which appears to have intra-aquifer groundwater flow with the Edwards Aquifer as water levels are at the same elevation.^[5]

Vertebrate fauna

Crocodylomorphs

Crocodylomorphs reported from the Trinity Group
Genus	Species	Location	Stratigraphic position	Material	Notes
Pachycheilosuchus^[6]	P. trinquei		Glen Rose Formation		A neosuchian related to Eusuchia. Had procoelous vertebrae.
Paluxysuchus^[7]	P. newmani		Twin Mountains Formation		A neosuchian related to Eusuchia

Dinosaurs

Dinosaurs reported from the Trinity Group
Genus	Species	Location	Stratigraphic position	Material	Notes
Acrocanthosaurus	A. atokensis^[8]		Twin Mountains Formation		A carcharodontosaurid
Arkansaurus^[9]	A. fridayi				An ornithomimosaur
Astrophocaudia^[10]	A. slaughteri		Paluxy Formation		A member of Somphospondyli
Cedarosaurus^[10]	C. weiskopfae		Paluxy Formation		A brachiosaurid
Paluxysaurus^[11]	P. jonesi		Twin Mountains Formation		Junior synonym of Sauroposeidon proteles
Sauroposeidon^[10]^[11]	S. proteles		Twin Mountains Formation		A member of Somphospondyli
Tenontosaurus	T. dossi^[12]		Twin Mountains Formation		An iguanodont
Convolosaurus^[13]	C. marri^[14]		Twin Mountains Formation		A basal ornithopod

Pterosaurs

Pterosaurs reported from the Trinity Group
Genus	Species	Location	Stratigraphic position	Material	Notes
Radiodactylus^[15]	R. langstoni		Glen Rose Formation		An azhdarchoid pterosaur

References

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•  Paleontology portal
•  Dinosaurs portal

1. Hill, R.T. (1888). "The Trinity formation of Arkansas, Indian Territory, and Texas". Science. 11 (258): 21. doi:10.1126/science.ns-11.258.21. PMID 17742326.
2. "Geologic Unit: Trinity". National Geologic Map Database. USGS. Retrieved 31 May 2014.
3. Suarez, Celina A.; Frederickson, Joseph; Cifelli, Richard L.; Pittman, Jeffrey G.; Nydam, Randall L.; Hunt-Foster, ReBecca K.; Morgan, Kirsty (2021-10-21). "A new vertebrate fauna from the Lower Cretaceous Holly Creek Formation of the Trinity Group, southwest Arkansas, USA". PeerJ. 9: e12242. doi:10.7717/peerj.12242. ISSN 2167-8359.
4. "Paleontologists Find Fossils of New Lizard and Fish Species in Arkansas | Sci-News.com". Breaking Science News | Sci-News.com. Retrieved 2021-11-21.
5. Saribudak, Mustafa (September 2016). "Geophysical mapping of Mount Bonnell fault of Balcones fault zone and its implications on Trinity-Edwards Aquifer interconnection, central Texas, USA". The Leading Edge. Society of Exploration Geophysicists. 35 (9): 752–758. doi:10.1190/tle35090752.1. Retrieved 12 September 2016.
6. Rogers, Jack V., II (2003). "Pachycheilosuchus trinquei, a new procoelous crocodyliform from the Lower Cretaceous (Albian) Glen Rose Formation of Texas". Journal of Vertebrate Paleontology 23 (1): 128–145. doi:10.1671/0272-4634(2003)23[128:PTANPC]2.0.CO;2.
7. Adams, T. L. (2013). "A new neosuchian crocodyliform from the Lower Cretaceous (late Aptian) Twin Mountains Formation of North-Central Texas". Journal of Vertebrate Paleontology 33: 85–10. doi:10.1080/02724634.2012.713277. edit
8. Harris, J. D. 1998. A reanalysis of Acrocanthosaurus atokensis, its phylogenetic status, and paleobiogeographic implications, based on a new specimen from Texas. New Mexico Museum of Natural History and Science, Bulletin 13: 1-75.
9. ReBecca K. Hunt; James H. Quinn (2018). "A new ornithomimosaur from the Lower Cretaceous Trinity Group of Arkansas". Journal of Vertebrate Paleontology. Online edition: e1421209. doi:10.1080/02724634.2017.1421209.
10. D'Emic, M. D. 2013. Revision of the sauropod dinosaurs of the Early Cretaceous Trinity Group, southern USA, with the description of a new genus. Journal of Systematic Palaeontology, 11:707-726.
11. Rose, P. J., 2007. A new titanosauriform sauropod (Dinosauria: Saurischia) from the Early Cretaceous of Central Texas and its phylogenetic relationships. Palaeontologia Electronica Vol. 10, Issue 2; 8A:65p, 2.6MB; http://palaeo-electronica.org/paleo/2007_2/00063/index.html (PDF: 65 pages)
12. Winkler, D., P. A. Murry, and L. L. Jacobs. 1997. A new species of Tenontosaurus (Dinosauria, Ornithopoda) from the early Cretaceous of Texas. Journal of Vertebrate Paleontology, 17:330-348.
13. Winkler, D. and P. A. Murry. 1989. Paleoecology and hypsilophodontid behavior at the Proctor Lake dinosaur locality (early Cretaceous) Texas. Geological Society of America, Special Paper 238:55-61.
14. Andrzejewski, Kate A.; Winkler, Dale A.; Jacobs, Louis L.; Forster, Catherine (2019). "A new basal ornithopod (Dinosauria: Ornithischia) from the Early Cretaceous of Texas". PLOS ONE. 14 (3): e0207935. doi:10.1371/journal.pone.0207935. PMC 6413910. PMID 30860999.
15. Andres, B.; Myers, T. S. (2013). "Lone Star Pterosaurs". Earth and Environmental Science Transactions of the Royal Society of Edinburgh: 1. doi:10.1017/S1755691013000303. edit