View source for Chesapecten

{{Short description|Extinct genus of bivalves}}
{{italic title}}
{{Automatic Taxobox
| image = Chesapecten_Jeffersonius_Outside.jpg
| image_caption = ''Chesapecten jeffersonius'' (outside)
| image2 = Chesapecten_Jeffersonius_Inside.jpg
| image2_caption = ''Chesapecten jeffersonius'' (inside)
| fossil_range = <!--{{fossil range|Early Miocene|Early Pleistocene}}-->{{Fossil range|20.4|0.7}} {{small|Early [[Miocene]] to Early [[Pleistocene]]}}
| taxon = Chesapecten
| type_species = ''Chesapecten nefrens''
| type_species_authority = Ward & Blackwater, 1975
}}
'''''Chesapecten''''' is an [[extinct]] [[genus]] of [[scallop]] known from marine strata from the early [[Miocene]] to the early [[Pleistocene]] of the Eastern [[United States]].<ref name=paleodb/>
It flourished in the shallow seas along the Mid-Atlantic during this period. Other scallops lived at the same time, but Chesapectens were the most abundant.
==Physical Description==
Like some other large scallops, the [[Bivalve shell|shells]] of ''Chesapecten'' are characterized by a pattern of wide ribs which radiate outward from the apex of the shell. A distinctive feature of ''Chesapecten'' is that the radial ribs on its shell are crossed by much smaller, rough, concentric ribs, which follow the contours of the edges of the shell (are "conmarginal"). The left [[valve (mollusc)|valve]] of ''Chesapecten'' is more convex than the right valve. The [[Bivalvia#Muscles|adductor muscle]] scar is large and rounded.
==Distribution==
The geographical distribution of ''Chesapecten'' is limited to the [[Atlantic coastal plain]] of [[North America]],<ref name=audubon/> where it can be found as far south as [[Florida]], and as far north as [[Delaware]].<ref name=adsabs/>
One species of ''Chesapecten'', ''[[Chesapecten jeffersonius]]'', is the state fossil of [[Virginia]].<ref name=virginiageo/>
==History of the taxonomy==
''Chesapecten'' was the first genus of North American fossil to be described and illustrated; a drawing of ''C. jeffersonius'' appeared in [[England|English]] [[Natural history|naturalist]] [[Martin Lister|Martin Lister's]] ''Historiae Conchyliorum, Liber III'' in 1687. However, Lister did not give ''Chesapecten'' its name.<ref name=audubon/> ''Chesapecten'' was [[Scientific classification#Authorities (author citation)|formally named]] in 1975 by the [[Paleontology|paleontologists]] Ward and Blackwater. In 1980, it was assigned to the [[Family (biology)|family]] ''[[Pectinidae]]'' by Harold E. Vokes.<ref name=paleodb/> The name ''Chesapecten'' comes from the [[Chesapeake Bay]], where [[erosion|eroding]] [[cliff]]s and outcrops along the [[beach]]es regularly expose specimens.<ref name=audubon/>
[[File:Chesapecten barnacles Pliocene VA.jpg|thumb|''Chesapecten'', [[barnacles]] and sponge borings (''[[Entobia]]'') from the [[Pliocene]] of York River, Virginia.]]
==Habitat and behavior==
''Chesapecten'' lived on the seabed in coastal waters ranging in depth from a few feet to 130 feet. When not moving, it is assumed to have rested its flatter right valve on the seafloor. It is very likely that ''Chesapecten'' could move suddenly to escape a predator by flapping its valves and using the resulting jet propulsion, in a manner similar to that of almost all living [[scallop]]s.<ref name=audubon/>
==Species==
[[File:Chesapecten jeffersonius fossil, Tellus Science Museum.jpg|thumb|267x267px|''Chesapecten jeffersonius'' fossil at the [[Tellus Science Museum]]]]
Different species dominated during different intervals of time: middlesexensis during the Miocene (Eastover Formation); ''[[Chesapecten jeffersonius]]'' during Early Pliocene (Lower [[Yorktown Formation]], about 4.5 to 4.3 million years ago); and madisonius during Late Pliocene time (Upper Yorktown Formation, about 4 to 3 million years ago).
Species in the genus ''Chesapecten'' include:
*†''C. coccymelus''<ref name=paleodb/>
*†''[[Chesapecten jeffersonius|C. jeffersonius]]''<ref name=paleodb/>
*†''C. madisonius''<ref name=paleodb/>
**†''C. m. sarasotensis''<ref name=waller/>
*†''C. marylandica''<ref name=miocenemd/>
*†''C. middlesexensis''<ref name=zipzoo/>
**†''C. m. bayshorensis''<ref name=waller/>
**†''C. m. hunterae''<ref name=waller/>
*†''C. monicae''<ref name=zipzoo/>
*†''C. nefrens''<ref name=miocenemd/>
*†''C. quinarius''<ref name=waller/>
*†''C. santamaria''<ref name=paleodb/>
*†''C. sayanus''<ref name=paleodb/>
*†''C. septenarius''<ref name=zipzoo/>
*†''C. skiptonensis''<ref name=paleodb/>
==References==
{{Reflist|refs=
*<ref name=audubon>National Audubon Society Field Guide to North American Fossils, page 465-466, Alfred A. Knopf Publishing New York, {{ISBN|0-394-52412-8}}
</ref>
*<ref name=paleodb>{{cite web
| url = https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=16548
| title = Information on Chesapecten from The Paleobiology Database
| access-date = 2010-09-29
}}</ref>
*<ref name=adsabs>{{Cite journal| bibcode = 2007AGUFMPP51E..05G
| title = NASA ADS: Seasonal Variations Preserved in an Extinct Neogene Scallop, Chesapecten, from Florida to Delaware, USA and its Implications for Paleobiogeography
| journal = American Geophysical Union
| volume = 51
| last1 = Goewert
| first1 = A. E.
| last2 = Surge
| first2 = D.
| year = 2007
}}</ref>
*<ref name=virginiageo>{{cite web
|url          = http://web.wm.edu/geology/virginia/vafossils/index.php
|title        = The Geology of Virginia
|accessdate   = 2010-09-29
|archive-url  = https://web.archive.org/web/20100508145144/http://web.wm.edu/geology/virginia/vafossils/index.php
|archive-date = 2010-05-08
|url-status     = dead
}}</ref>
*<ref name=miocenemd>{{cite web
| url = http://www.mgs.md.gov/esic/publications/B20/pect.html
| title = Bulletin 20: Miocene Fossils of Maryland
| accessdate = 2010-09-29
| url-status = dead
| archiveurl = https://web.archive.org/web/20100826052124/http://www.mgs.md.gov/esic/publications/B20/pect.html
| archivedate = 2010-08-26
}}</ref>
*<ref name=zipzoo>{{cite web
|url          = http://zipcodezoo.com/Animals/C/Chesapecten_nefrens/
|title        = Chesapecten Nefrens - zipcodezoo.com
|accessdate   = 2010-09-29
|archive-url  = https://web.archive.org/web/20120820201137/http://zipcodezoo.com/Animals/C/Chesapecten_nefrens/
|archive-date = 2012-08-20
|url-status     = dead
}}</ref>
*<ref name=waller>{{cite web
| url = https://www.floridamuseum.ufl.edu/files/9815/3022/4121/vol56no1archival.pdf
| title = Systematics and biostratigraphy of ''Chesapecten'' and ''Carolinapecten'' (Mollusca: Bivalvia: Pectinidae) in the upper Miocene and Pliocene "Lower Tamiami Formation" of southwestern Florida
| accessdate = 2018-08-19
}}</ref>
}}
==Further reading==
[http://www.fossilguy.com/sites/calvert/calv_inv.htm Online photo gallery with several pictures of ''Chesapecten nefrens'']<br>
[https://web.archive.org/web/20160303222714/http://data.gbif.org/species/16363896 Information about ''Chesapecten'' from the Global Biodiversity Information Facility]<br>
[https://images.google.com/images?hl=en&q=Chesapecten Images of ''Chesapecten'' from Google Images]
{{Taxonbar|from=Q5092898}}
[[Category:Pectinidae]]
[[Category:Prehistoric bivalve genera]]
[[Category:Neogene bivalves]]
[[Category:Miocene genus first appearances]]
[[Category:Pleistocene genus extinctions]]
[[Category:Prehistoric bivalves of North America]]