The Choptank Formation is a

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the East Coast of the United States, Atlantic Coast and the Appalachian Mountains. The geography an ...

and

Maryland Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; ...

. It preserves

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

dating from the

Miocene epoch The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...

of the

Neogene The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago (Mya) to the beginning of the present Quaternary Period Mya. ...

period.

Fossils

The Choptank Formation is extremely fossiliferous. Some of the fossil species represented include the following:

Sharks

*''

Otodus megalodon Megalodon (''Otodus megalodon''), meaning "big tooth", is an extinct species of mackerel shark that lived approximately 23 to 3.6 million years ago (Mya), from the Early Miocene to the Pliocene epochs. It was formerly thought to be a membe ...

'' *'' Carcharodon hastalis'' *'' Isurus oxyrhincus'' *

Carcharomodus escheri ''Carcharomodus escheri'', commonly nicknamed the serrated mako shark or Escher's mako shark, is an extinct lamnid that lived during the Miocene. It has been formerly thought to have been the transitional between the broad-toothed "mako" ''Cosmop ...

*'' Physogaleus contortus'' *'' Galeocerdo aduncus'' *''

Carcharhinus ''Carcharhinus'' is the type genus of the family Carcharhinidae, the requiem sharks. One of 12 genera in its family, it contains over half of the species therein. It contains 35 extant and eight extinct species to date, with likely more species ...

'' *''

Hemipristis serra ''Hemipristis serra'' is an extinct species of weasel shark which existed during the Miocene epoch. It was described by Louis Agassiz Jean Louis Rodolphe Agassiz ( ; ) FRS (For) FRSE (May 28, 1807 – December 14, 1873) was a Swiss-born ...

'' *'' Squatina sp.'' *'' Notorhyncus cepedianus'' *''

Carcharias ''Carcharias'' is a genus of sand tiger sharks belonging to the family Odontaspididae. Once bearing many prehistoric species, all have gone extinct with the exception of the critically endangered sand tiger shark. Description ''Carcharias'' ar ...

'' *''

Isurus retroflexus ''Isurus'' is a genus of mackerel sharks in the family Lamnidae, commonly known as the mako sharks. Description The two living species are the common shortfin mako shark (''I. oxyrinchus'') and the rare longfin mako shark (''I. paucus''). They ...

'' *'' Parotodus benedeni'' *''

Alopias vulpinus The common thresher (''Alopias vulpinus''), also known as Atlantic thresher, is the largest species of thresher shark, family Alopiidae, reaching some in length. About half of its length consists of the elongated upper lobe of its caudal fin. Wi ...

'' *'' Alopias grandis'' *'' Cetorhinus'' *''

Negaprion brevirostris The lemon shark (''Negaprion brevirostris'') is a species of shark from the family Carcharhinidae and is classified as a Vulnerable species by the International Union for the Conservation of Nature. Lemon sharks can grow to in length. They are o ...

'' *''

Rhizoprionodon ''Rhizoprionodon'' is a genus of requiem sharks, and part of the family Carcharhinidae, commonly known as sharpnose sharks because of their long, pointed snouts. Species * '' Rhizoprionodon acutus'' ( Rüppell, 1837) (milk shark) * '' Rhizoprio ...

'' *'' Sphryna laevissima''

Rays and Other Cartilaginous Fish

*''

Aetobatus ''Aetobatus'' is a genus of eagle rays native to the Atlantic, Pacific and Indian Oceans. It was formerly placed in Myliobatidae, but is now placed in its own family Aetobatidae based on salient differences from myliobatids, especially the pecto ...

arcuatus'' *'' Pteromyaleus sp.'' *''

Dasyatis ''Dasyatis'' (Greek δασύς ''dasýs'' meaning rough or dense and βατίς ''batís'' meaning skate) is a genus of stingray in the family Dasyatidae that is native to the Atlantic, including the Mediterranean. In a 2016 taxonomic revisi ...

rugosa'' *''

probsti'' *'' Pinthicus stenodon''

Fish

*''

Acipenseridae Sturgeon is the common name for the 27 species of fish belonging to the family Acipenseridae. The earliest sturgeon fossils date to the Late Cretaceous, and are descended from other, earlier acipenseriform fish, which date back to the Early ...

indet.'' *'' Opsanus sp.'' *''

Serranidae The Serranidae are a large family of fishes belonging to the order Perciformes. The family contains about 450 species in 65 genera, including the sea basses and the groupers (subfamily Epinephelinae). Although many species are small, in some c ...

sp.'' *''

Pogonias ''Pogonias'' is a genus of ray-finned fish in the family Sciaenidae. It was formerly believed to be a monotypic genus only containing the black drum, but a second species was re-described in 2019. Species There are currently two described spec ...

sp.'' *''

Sciaenops The red drum (''Sciaenops ocellatus''), also known as redfish, channel bass, puppy drum, spottail bass, or simply red, is a game fish found in the Atlantic Ocean from Massachusetts to Florida and in the Gulf of Mexico from Florida to northern Mexi ...

sp.'' *''

Tautog The tautog (''Tautoga onitis''), also known as the blackfish, is a species of wrasse native to the western Atlantic Ocean from Nova Scotia to South Carolina. This species inhabits hard substrate habitats in inshore waters at depths from . It is ...

a sp.'' *''

Acanthocybium Wahoo (''Acanthocybium solandri'') is a scombrid fish found worldwide in tropical and subtropical seas. It is best known to sports fishermen, as its speed and high-quality flesh makes it a prized and valued game fish. In Hawaii, the wahoo is kno ...

cf. solandri'' *''

Thunnus ''Thunnus'' is a genus of ocean-dwelling, ray-finned bony fish from the mackerel family, Scombridae. More specifically, ''Thunnus'' is one of five genera which make up the tribe Thunnini – a tribe that is collectively known as the tunas. A ...

sp.'' *''

Istiophorus The sailfish is one or two species of marine fish in the genus ''Istiophorus'', which belong to the family Istiophoridae (marlins). They are predominantly blue to gray in colour and have a characteristically large dorsal fin known as the sa ...

cf. platypterus'' *'' Mola cf. pileata'' *'' Ariopsis aff. A. felis'' *'' Trisopterus sculptus'' *'' Micromesistius cognatus'' *''

Prionotus ''Prionotus'' is a genus of marine ray-finned fishes belonging to the family Triglidae, one of two genera belonging to the subfamily Prionotinae, the searobins. These fishes are found in the Western Atlantic Ocean and eastern Pacific Ocean, i ...

Cetaceans

*'' Aglaocetus sp.'' *''

Cetotherium ''Cetotherium'' ("whale beast") is an extinct genus of baleen whales from the family Cetotheriidae. Taxonomy The family Cetotheriidae and the genus ''Cetotherium'' (sensu lato) have been used as wastebaskets for all kinds of baleen whales, mo ...

sp.'' *'' Delphinodon sp.'' *'' Eurhinodelphis sp.'' *''

Macrokentriodon ''Macrokentriodon'' is an extinct genus of giant dolphin once assigned to the paraphyletic/polyphyletic family Kentriodontidae. Remains have been found in the late Miocene (Serravallian) Choptank Formation of United States. ''Macrokentriodon'' ...

morani'' *''

Mesocetus ''Mesocetus'' is an extinct genus of baleen whale from the Miocene of Europe ( Antwerp, Belgium and Balkans). Description ''Mesocetus'' is similar to other tranatocetids in having rostral bones that override the frontals and contact the parietal ...

'' *'' Parietobalaena'' *''

Orycterocetus ''Orycteocetus'' is an extinct genus of sperm whale from the Miocene of the northern Atlantic Ocean. Classification ''Orycterocetus'' is a member of Physeteroidea closely related to crown-group sperm whales. The type species, ''O. quadratiden ...

'' *'' Pelocetus''

Pinnipeds

*'' Callophoca obscura'' *'' Leptophoca proxima'' *'' Prophoca sp.''

Crocodilians

*''

Thecachampsa ''Thecachampsa'' is an extinct genus of gavialoid crocodylian, traditionally regarded as a member of the subfamily Tomistominae. Fossils have been found from the eastern United States in deposits of Miocene age. Those named in the 19th century ...

antiquus'' *''

sericodon''

Invertebrates

*'' Chesapecten nefrens'' *'' Chesacardium'' *'' Euspira heros'' *'' Mariacolpus octonnaria'' *'' Macrocallista marylandica'' *'' Stewartia anodonta'' *'' Marvacrassitella marylandica'' *''

Ecphora Ecphora is the common name for a group of extinct predatory marine (ocean), marine gastropod mollusks within the family Muricidae, the rocks snails or murexes. The common name is based on the first officially described genus, ''Ecphora (genus), E ...

'' *''

Panopea In Greek mythology, Panopea ( Ancient Greek: Πανόπεια ''Panopeia'') or Panope (Πανόπη) may refer to various characters. The names mean 'panorama' or means 'of the beautiful husband'. * Panope or Poenope, Hyginus, ''Fabulae'' Prefac ...

'' *'' Albertella aberti''

Terrestrial Mammals

*''

Cynarctus ''Cynarctus'' is an extinct genus of the Borophaginae subfamily of canids native to North America. The genus was first founded by W. D. Matthew in 1901, based from a pair of lower jaws, ''Cynarctus saxitilis,'' found in the Pawnee Creek Beds o ...

wangi'' *''

Gomphotherium ''Gomphotherium'' (; "welded beast") is an extinct genus of proboscids from the Neogene and early Pleistocene of Eurasia, Africa, North America and Asia. As of 2021, two species, ''G. annectens'' and possibly ''G. subtapiroideum'', are also kn ...

calvertensis'' *''

Hipparion ''Hipparion'' (Greek, "pony") is an extinct genus of horse that lived in North America, Asia, Europe, and Africa during the Miocene through Pleistocene ~23 Mya—781,000 years ago. It lived in non-forested, grassy plains, shortgrass prairie or st ...

cf. phosphorum''

References

* Neogene Maryland Neogene geology of Virginia {{Virginia-geologic-formation-stub

Fossils

Sharks

Rays and Other Cartilaginous Fish

Fish

Cetaceans

Pinnipeds

Crocodilians

Invertebrates

Terrestrial Mammals

See also

References