Demopolis Chalk

Demopolis Chalk
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

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 stage 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]

Vertebrate paleofauna

Cartilaginous fish of the Demopolis Chalk Formation
Genus	Species	Presence	Notes	Images
Cretolamna	C. appendiculata[2]		An Otodontid	Squalicorax sp.
Scapanorhynchus	Scapanorhynchus sp.[2]		A mitsukurinid
Squalicorax	S. kaupi		Anacoracids
Squalicorax	S. pristodontus[2]		Anacoracids
Ischyrhiza	I. mira[2]		A sclerorhynchid
Carcharias	C. samhammeri		A Odontaspidid
Archaeolamna	A. "kopingensis"		A Archaeolamnid

Bony fish of the Demopolis Chalk Formation
Genus	Species	Presence	Notes	Images
Enchodus	E. petrosus[2]		An enchodontid	Enchodus petrosus
Protosphyraena	P. gladius[2]		A pachycormid
Xiphactinus	X. vetus[4]		An ichthyodectid

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

Mosasaurs of the Demopolis Chalk
Genus	Species	Presence	Notes	Images
Mosasaurus	M. conodon[2]		A mosasaurine	Plioplatecarpus
Plioplatecarpus	P. primaevus[5]		A plioplatecarpine
Prognathodon	P. rapax		A mosasaurine
Prognathodon	P. solvayi[2]		A mosasaurine

Plesiosaurs of the Demopolis Chalk
Genus	Species	Presence	Notes	Images
Elasmosaurus	Elasmosaurus sp.[2]		An elasmosaurid	Elasmosaurus sp.

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.
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 2009-02-02.
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.
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.
Everhart, Mike (2008-04-18). "The Platecarpus Collection: A virtual collection of Platecarpus specimens from Kansas and elsewhere". Oceans of Kansas Paleontology. Retrieved 2009-02-02.

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