Calvert Formation

Last updated
Calvert Formation
Stratigraphic range: Early to Middle Miocene (Aquitanian-Langhian)
2016-07-20 10 17 03 Cliffs to the south of Grays Creek in Calvert Cliffs State Park, Calvert County, Maryland.jpg
Outcrops of the Calvert Formation at the Calvert Cliffs State Park
Type Formation
Unit of Chesapeake Group
Underlies Choptank Formation
Overlies Old Church Formation
Location
Region Maryland, Virginia, Delaware
CountryUnited States
Type section
Named for Calvert County

The Calvert Formation is a geologic formation in Maryland, Virginia, and Delaware. It preserves fossils dating back to the early to middle Miocene epoch of the Neogene period, between 23 to 14 million years ago [1] . It is one of the three formations which make up the Calvert Cliffs, all of which are part of the Chesapeake Group.

Contents

Fossils

Carcharocles megalodon partially buried in gravel along the Calvert Cliffs, Maryland Meg in gravel.jpg
Carcharocles megalodon partially buried in gravel along the Calvert Cliffs, Maryland
Fossils from the Calvert Formation, Zone 10, Calvert Co., MD (Miocene) Calvert Zone 10 Calvert Co MD 2.jpg
Fossils from the Calvert Formation, Zone 10, Calvert Co., MD (Miocene)

The Calvert Formation is extremely fossiliferous, although the most fossiliferous layers constitute a relative small section of it, dating to about 16 to 14.5 million years ago. Sediments under these layers are composed of either fine sand with few shells or (for the earliest layers) diatomite. [1] Some of the fossil species represented include the following: [2] [3]

Carcharocles megalodon partially buried in gravel along the Calvert Cliffs, Maryland Meg in gravel.jpg
Carcharocles megalodon partially buried in gravel along the Calvert Cliffs, Maryland

Chondrichthyes

Holocephalians

GenusSpeciesFamilyLocationStratigraphic PositionMaterialNotesImages
Edaphodon E. sp Callorhynchidae two well preserved mandibular platesSimilar to E. sweeti
Ischyodus I.sp Callorhynchidae many tooth fragments occasional mandibular plates
Chimaera C. sp Cimaeridae

Elasmobranchii

GenusSpeciesLocationFamilyStratigraphic PositionMaterialNotesImages
Notorynchus N. primigenius Hexanchidae Similar to extant N. cepedianus but differs in distribution.
Hexanchus H. gigas Hexanchidae Far less common then N. primigenus
Echinorhinus E. blakei EchinorhinidaeTeeth and bramble thornsOne of the rarest sharks in the cliffs, prefers deeper waters
Squalus S. sp. 1

S. sp. 2

SqualidaeVery rareTwo forms of teeth, one (S.sp 2) similar to Squalus acanthias
Squatina S.sp Squatinidae Teeth and Dermal thorns
Rhincodon R. typus Rhincodonidae Very similar to modern R. typus
A living whale shark Rhincodon typus fgbnms.jpg
A living whale shark
Carcharias C. cuspidatus

C. taurus C. reticulatus

odontaspididae

Rays and other cartilaginous fish

Bony fish

Cetaceans

Pinnipeds

Crocodilians

Invertebrates

Terrestrial mammals


Birds

See also

References

  1. 1 2 Carnevale, Giorgio; Godfrey, Stephen James (2018). "Miocene bony fishes from the Calvert, Choptank, St. Marys and Eastover Formations, Chesapeake Group, Maryland and Virginia". Smithsonian Contributions to Paleobiology (100).
  2. ↑ Godfrey, Stephen J., ed. (2018-09-25). "The Geology and Vertebrate Paleontology of Calvert Cliffs, Maryland, USA". Smithsonian Contributions to Paleobiology (100): 2–274. doi: 10.5479/si.1943-6688.100 . ISSN   1943-6688.
  3. ↑ "Paleobiology Collections Search". collections.nmnh.si.edu. Retrieved 2020-08-14.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.