Demopolis Chalk

The Demopolis Chalk is a geological formation in North America, within the U.S. states of Alabama, Mississippi, and Tennessee. The chalk was formed by pelagic sediments deposited along the eastern edge of the Mississippi embayment during the middle Campanian age of the Late Cretaceous.^[1] It is a unit of the Selma Group and consists of the upper Bluffport Marl Member and a lower unnamed member.^[2] Dinosaur and mosasaur remains are among the fossils that have been recovered from the Demopolis Chalk.^[2][3]

Demopolis Chalk
Stratigraphic range: Upper Cretaceous
Type	Geological formation
Unit of	Selma Group
Sub-units	Bluffport Marl Member
Underlies	Ripley Formation
Overlies	Mooreville Chalk Formation
Lithology
Primary	Chalk
Location
Region	Alabama, Mississippi, Tennessee
Country	United States
Type section
Named for	Demopolis, Alabama

Vertebrate paleofauna

Fish

Cartilaginous fish

Cartilaginous fish of the Demopolis Chalk Formation
Genus	Species	Presence	Notes	Images
Chimaeriformes indet.[4]		Alabama[4]		Ischyrhiza mira rostral spines Teeth of Scapanorhynchus texanus Squalicorax sp.
Cretolamna	C. appendiculata[2][4]	Alabama[4]	An otodontid
Ischyrhiza	I. mira[2][4]	Alabama[4]	A sclerorhynchid
Scapanorhynchus	S. texanus[4]	Alabama[4]	A mitsukurinid
Serratolamna	S. serrata?[4]	Alabama[4]	A lamniform shark
Squalicorax	S. kaupi[4]	Alabama[4]	Anacoracids
	S. pristodontus[2][4]
	S. sp.[4]

Bony fish

Bony fish of the Demopolis Chalk Formation
Genus	Species	Presence	Notes	Images
Enchodus	E. ferox[4]	Alabama[4]	Enchodontids	Enchodus petrosus Protosphyraena Stratodus
	E. gladiolus[4]
	E. petrosus[4]
Protosphyraena	P. sp.[4]	Alabama[4]	A pachycormiform
Saurodon	S. sp.[4]	Alabama[4]	An ichthyodectiform
Stratodus	S. sp.[4]	Alabama[4]	An aulopiform
Xiphactinus	X. vetus[5]		An ichthyodectid

Reptiles

Dinosaurs

Indeterminate hadrosaurid remains have been found in Tennessee.^[3] Possible indeterminate tyrannosaurid remains have been found in Alabama.^[3]

Dinosaurs of the Demopolis Chalk Formation
Genus	Species	Presence	Notes	Images
Appalachiosaurus[1][3]	A. montgomeriensis[1][3]	Geographically present in Alabama.[3]	A tyrannosauroid	Appalachiosaurus

Crocodylians

Crocodylians of the Demopolis Chalk Formation
Genus	Species	Presence	Notes	Images
Borealosuchus	B. sp.[4]	Alabama[4]	An eusuchian	Borealosuchus skull

Mosasaurs

Mosasaurs of the Demopolis Chalk
Genus	Species	Presence	Notes	Images
Clidastes	C. propython[4]	Alabama[4]	A mosasaurine	Clidastes propython Plioplatecarpus
Halisaurus	H. sp.[4]	Alabama[4]	A halisaurine
Mosasaurus	M. conodon[2][4]	Alabama[4]	Mosasaurines
	M. cf. missouriensis[4]
Platecarpus	P. cf. somenensis[4]	Alabama[4]	A plioplatecarpine
Plioplatecarpus	P. primaevus[6]		A plioplatecarpine
Prognathodon	P. rapax[2]		Mosasaurines
	P. cf. solvayi[2]
Tylosaurus	T. sp.[4]	Alabama[4]	A tylosaurine

Turtles

Turtles of the Demopolis Chalk
Genus	Species	Presence	Notes	Images
Asmodochelys	A. parhami[7]	Geographically present in Alabama and Mississippi.[7]	A marine ctenochelyid turtle	Protostega gigas
Chedighaii	C. barberi[4]	Alabama[4]	A bothremydid
Ctenochelys	C. cf. tennuitesta[4]	Alabama[4]	A ctenochelyid
Prionochelys	P. matutina?[4]	Alabama[4]	A ctenochelyid
Protostega	P. gigas[4]	Alabama[4]	A protostegid

See also

• Paleontology portal
• Dinosaurs portal

• List of dinosaur-bearing rock formations
• List of fossil sites

References

1. Carr, T.D.; Williamson, T.E.; Schwimmer, D.R. (2005). "A new genus and species of tyrannosauroid from the Late Cretaceous (middle Campanian) Demopolis Formation of Alabama". Journal of Vertebrate Paleontology. 25 (1): 119–143. doi:10.1671/0272-4634(2005)025[0119:ANGASO]2.0.CO;2. S2CID 86243316.
2. Kiernan, Caitlin R. (2002). "Stratigraphic distribution and habitat segregation of mosasaurs in the Upper Cretaceous of western and central Alabama, with an historical review of Alabama mosasaur discoveries". Journal of Vertebrate Paleontology. 22 (1): 91–103. doi:10.1671/0272-4634(2002)022[0091:SDAHSO]2.0.CO;2. Retrieved 2024-06-12.
3. Weishampel, David B; et al. (2004). "Dinosaur distribution (Late Cretaceous, North America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 574-588. ISBN 0-520-24209-2.
4. Kejiri, T.; Ebersole, J.A.; Blewitt, H.L.; Ebersole, S.M. (2013). "An Overview of Late Cretaceous Vertebrates from Alabama". Bulletin of the Alabama Museum of Natural History. 31 (1): 46–71.
5. Schwimmer, D. R.; Stewart, J. D.; Williams, G. Dent (1997). "Xiphactinus vetus and the Distribution of Xiphactinus Species in the Eastern United States". Journal of Vertebrate Paleontology. 17 (3): 610–615. doi:10.1080/02724634.1997.10011007.
6. Everhart, Mike (2008-04-18). "The Platecarpus Collection: A virtual collection of Platecarpus specimens from Kansas and elsewhere". Oceans of Kansas Paleontology. Archived from the original on 2024-03-17. Retrieved 2024-06-12.
7. Andrew D. Gentry; Jun A. Ebersole; Caitlin R. Kiernan (2019). "Asmodochelys parhami, a new fossil marine turtle from the Campanian Demopolis Chalk and the stratigraphic congruence of competing marine turtle phylogenies". Royal Society Open Science. 6 (12): Article ID 191950. Bibcode:2019RSOS....691950G. doi:10.1098/rsos.191950. PMC 6936288. PMID 31903219.