Choptank Formation Explained

The Choptank Formation is a geologic formation in Virginia and Maryland. It preserves fossils dating from the mid-late Miocene of the Neogene period, from the latest Langhian to the early Tortonian (13.9 to 11 million years ago).^[1]

Fossils

The Choptank Formation is extremely fossiliferous. Some of the fossil species represented include the following:^{[2] [3]}

Sharks

• Otodus megalodon
• Carcharodon hastalis
• Isurus oxyrhincus
• Carcharomodus escheri
• Physogaleus contortus
• Galeocerdo aduncus
• Carcharhinus
• Hemipristis serra
• Squatina sp.
• Notorhyncus cepedianus
• Carcharias
• Isurus retroflexus
• Parotodus benedeni
• Alopias vulpinus
• Alopias grandis
• Cetorhinus
• Negaprion brevirostris
• Rhizoprionodon
• Sphryna laevissima

Rays and Other Cartilaginous Fish

• Aetobatus arcuatus
• Pteromyaleus sp.
• Dasyatis rugosa
• Dasyatis probsti
• Pinthicus stenodon

Fish

• Acipenseridae indet.
• Opsanus sp.
• Serranidae indet
• Pogonias sp.
• Sciaenops sp.
• Tautoga sp.
• Acanthocybium cf. solandri
• Thunnus sp.
• Istiophorus cf. platypterus
• Mola cf. pileata
• Ariopsis aff. A. felis
• Trisopterus sculptus
• Micromesistius cognatus
• Prionotus

Cetaceans

• Aglaocetus sp.
• Cetotherium sp.
• Delphinodon sp.
• Eurhinodelphis sp.
• Macrokentriodon morani
• Mesocetus
• Parietobalaena
• Orycterocetus
• Pelocetus

Pinnipeds

• Callophoca obscura
• Leptophoca proxima
• Prophoca sp.

Crocodilians

• Thecachampsa antiquus
• Thecachampsa sericodon

Invertebrates

• Chesapecten nefrens
• Chesacardium
• Euspira heros
• Mariacolpus octonnaria
• Macrocallista marylandica
• Stewartia anodonta
• Marvacrassitella marylandica
• Ecphora
• Panopea
• Albertella aberti

^[4]

Terrestrial Mammals

• Cynarctus wangi
• Gomphotherium calvertensis
• Hipparion cf. phosphorum

See also

• List of fossiliferous stratigraphic units in Virginia
• Paleontology in Virginia
• Paleontology in Maryland
• Calvert Cliffs State Park
• List of fossiliferous stratigraphic units in Maryland
• Chesapeake Group

References

• Web site: Fossilworks: Gateway to the Paleobiology Database. ((Various Contributors to the Paleobiology Database)). 17 December 2021.

Notes and References

1. 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. 2018-09-25. Godfrey. Stephen J.. The Geology and Vertebrate Paleontology of Calvert Cliffs, Maryland, USA. Smithsonian Contributions to Paleobiology. 100. 2–274. 10.5479/si.1943-6688.100. 1943-6688. free.
3. Web site: Paleobiology Collections Search. 2020-08-14. collections.nmnh.si.edu.
4. Web site: Collections. 2020-08-14. The Fossil Forum. en-US.