Demopolis Chalk

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 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]

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]

A mosasaurine

M. cf. missouriensis[4]

Platecarpus

P. cf. somenensis[4]

Alabama[4] and Mississippi[6]

A plioplatecarpine

Plioplatecarpus

P. sp. nov.[7]

Mississippi[6]

A plioplatecarpine

Tylosaurus

T. sp.[4]

Alabama[4] and Mississippi[6]

A tylosaurine

Turtles

Turtles of the Demopolis Chalk
Genus Species Presence Notes Images

Asmodochelys

A. parhami[8]

Geographically present in Alabama and Mississippi.[8]

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

References

  1. ^ a b c 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. ^ a b c d e f 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. ^ a b c d e f 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. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as Ikejiri, 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. ^ a b c Rempert, Trevor H; Martens, Brennan P; Vinkeles Melchers, Alexander P. M. (2024-01-09). "New Mosasaur remains from the Upper Cretaceous of Mississippi". The Mosasaur - the Journal of the Delaware Valley Paleontological Society. 13: 79–90. doi:10.5281/zenodo.10472410.
  7. ^ 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.
  8. ^ a b 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) 191950. Bibcode:2019RSOS....691950G. doi:10.1098/rsos.191950. PMC 6936288. PMID 31903219.

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