Demopolis Chalk
Stratigraphic range: Upper Cretaceous
TypeGeological formation
Unit ofSelma Group
Sub-unitsBluffport Marl Member
UnderliesRipley Formation
OverliesMooreville Chalk Formation
Lithology
PrimaryChalk
Location
RegionAlabama, Mississippi, Tennessee
CountryUnited States
Type section
Named forDemopolis, 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

Fish

Cartilaginous fish

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

S. pristodontus[2]

Ischyrhiza

I. mira[2]

A sclerorhynchid

Carcharias

C. samhammeri

A Odontaspidid

Archaeolamna

A. "kopingensis"

A Archaeolamnid

Bony fish

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

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

Mosasaurs

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. cf. rapax

A mosasaurine

Plesiosaurs

Plesiosaurs of the Demopolis Chalk
Genus Species Presence Notes Images

Elasmosaurus

Elasmosaurus sp.[2]

An elasmosaurid
Elasmosaurus sp.

See also

References

  1. 1 2 3 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.
  2. 1 2 3 4 5 6 7 8 9 10 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.
  3. 1 2 3 4 5 6 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. ↑ 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.
  5. ↑ 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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