The Chelydridae is a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideall ...

turtle Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked t ...

s that has seven extinct and two extant

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomencl ...

. The extant genera are the snapping turtles, ''

Chelydra ''Chelydra'' is one of the two extant genera of the snapping turtle family, Chelydridae, the other being ''Macrochelys'', the much larger alligator snapping turtle. The snapping turtles are native to the Americas, with ''Chelydra'' having th ...

'' and ''

Macrochelys ''Macrochelys'' is a genus of very large freshwater turtles in the family Chelydridae from Southeastern United States. Only a single extant species was recognized until a 2014 study divided it into two, or possibly three species. Extant species ...

''. Both are

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to the

Western Hemisphere The Western Hemisphere is the half of the planet Earth that lies west of the prime meridian (which crosses Greenwich, London, United Kingdom) and east of the antimeridian. The other half is called the Eastern Hemisphere. Politically, the term W ...

. The extinct genera are ''

Acherontemys ''Acherontemys'' is an extinct genus of turtle from Miocene of United States. Taxonomy It was assigned to Chelydridae by Robert L. Carroll in 1988, while Hutchison classified it within Emydidae Emydidae (Latin ''emys'' (freshwater tortoise ...

'', ''

Chelydrops ''Chelydrops'' is an extinct genus of Chelydridae from Miocene of North America. Only one species is described, ''Chelydrops stricta'' (Matthew, 1924). The genus was considered by Hutchison (2008) to be a junior synonym of the genus ''Macrochely ...

'', ''

Chelydropsis ''Chelydropsis'' is an extinct genus in the family of snapping turtle that lived from the Oligocene to the Pliocene in Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its ...

'', ''

Emarginachelys ''Emarginachelys cretacea'' is a turtle belonging to the group Cryptodira, known from well preserved fossils from the Maastrichtian stage of the Late Cretaceous of Montana Montana () is a state in the Mountain West division of the West ...

'', ''

Macrocephalochelys ''Macrocephalochelys'' is an extinct genus of turtles in the family Chelydridae. It was first described from a partial skull from the Pliocene found in Ukraine by Piboplichko and Taraschchuk in 1960. It was assigned to the family Chelydridae ...

'', ''

Planiplastron ''Planiplastron'' is an extinct genus of snapping turtle. It was first described by Chkhikvadze in 1971. It was assigned to the family Chelydridae The Chelydridae is a family of turtles that has seven extinct and two extant genera. The extan ...

'', and ''

Protochelydra ''Protochelydra zangerli'' is an extinct species of chelydid in the extinct genus ''Protochelydra'' of Chelydridae The Chelydridae is a family of turtles that has seven extinct and two extant genera. The extant genera are the snapping turtles ...

''.

Fossil history

The Chelydridae have a long

fossil 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 in ...

history, with

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

species reported from North America as well as all over Asia and Europe, far outside their present range. The earliest described chelydrid is ''

Emarginachelys cretacea ''Emarginachelys cretacea'' is a turtle belonging to the group Cryptodira, known from well preserved fossils from the Maastrichtian stage of the Late Cretaceous of Montana Montana () is a state in the Mountain West division of the West ...

'', known from well-preserved fossils from the

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from ...

stage of the Late Cretaceous of

Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Colum ...

. Another well-preserved fossil chelydrid is the Late

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''palaió ...

Protochelydra zangerli ''Protochelydra zangerli'' is an extinct species of chelydid in the extinct genus ''Protochelydra'' of Chelydridae The Chelydridae is a family of turtles that has seven extinct and two extant genera. The extant genera are the snapping turtles ...

'' from

North Dakota North Dakota () is a U.S. state in the Upper Midwest, named after the indigenous Dakota Sioux. North Dakota is bordered by the Canadian provinces of Saskatchewan and Manitoba to the north and by the U.S. states of Minnesota to the east, South ...

. The

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the under ...

of ''P. zangerli'' is higher-domed than that of the recent ''Chelydra'', a trait conjectured to be associated with the coexistence of large, turtle-eating

crocodilia Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period ( Cenomanian stage) and are the closest living ...

ns. Another genus, ''Chelydropsis'', contains several well-known

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago ...

n chelydrid

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

that existed from the

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

to the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58C. acutirostris'') only occupy the northwestern corner of the continent, reflecting their recent arrival from Central America as part of the

Great American Interchange The Great American Biotic Interchange (commonly abbreviated as GABI), also known as the Great American Interchange and the Great American Faunal Interchange, was an important late Cenozoic paleozoogeographic biotic interchange event in which la ...

Gallery

Chelydropsis murchisoni 01.jpg, ''

murchisoni'' fossil remains: left: juvenile, right: adult Common Snapping Turtle Close Up.jpg,

Common snapping turtle The common snapping turtle (''Chelydra serpentina'') is a species of large freshwater turtle in the family Chelydridae. Its natural range extends from southeastern Canada, southwest to the edge of the Rocky Mountains, as far east as Nova Scotia ...

Taum Sauk Mountain Taum Sauk Mountain in the Saint Francois Mountains is the highest natural point in the U.S. state of Missouri at 1,772 feet (540 m). The topography of Taum Sauk is that of an elongated ridge with a NNW-SSE orientation rather than a peak. De ...

State Park Submerged Snapping turtle.jpg, Two-year-old captive-raised snapping turtle from

Pennsylvania Pennsylvania (; (Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, Mary ...

Snapping turtlewithcan.jpg, Female next to can to show size Alligator Snapping Turtle Skeleton.jpg, Skeleton of alligator snapping turtle at the

Museum of Osteology The Museum of Osteology, located in Oklahoma City, Oklahoma, U.S., is a private museum devoted to the study of bones and skeletons (osteology). This museum displays over 450 skeletons of animal species from all over the world. With another 7,000 ...

References

* de Broin, F. (1969). ''Contribution a l'etude des cheloniens. Cheloniens continentaux du Cretace Superieur et du Tertiaire de France. Memoires du

Muséum National d'Histoire Naturelle The French National Museum of Natural History, known in French as the ' (abbreviation MNHN), is the national natural history museum of France and a ' of higher education part of Sorbonne Universities. The main museum, with four galleries, is loc ...

.'' Vol. C, No. XXVIII. * Ericson, B.R. (1973). A new chelydrid turtle (''Protochelydra zangerli''), from the late Paleocene of North Dakota. ''Scientific Publications of the Science Museum of Minnesota, New Series.'' 2(2):1-16. * Gaffney, E.S. (1975).

Phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...

of the chelydrid turtles: a study of shared derived characters in the skull. ''Fieldiana Geology'' 33:157-178. * Parham, J.F., C.R. Feldman, and J.R. Boore (2006). The complete

mitochondrial genome Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial DNA ...

of the enigmatic bigheaded turtle (''Platysternon''): description of unusual genomic features and the reconciliation of phylogenetic hypotheses based on mitochondrial and

nuclear DNA Nuclear DNA (nDNA), or nuclear deoxyribonucleic acid, is the DNA contained within each cell nucleus of a eukaryotic organism. It encodes for the majority of the genome in eukaryotes, with mitochondrial DNA and plastid DNA coding for the rest. It ...

. ''BMC Evol Biol.'' 6: 11. Published online February 7, 2006. . * Whetstone, K.N. (1978). A new genus of cryptodiran turtles (Testudinoidea, Chelydridae) from the Upper Cretaceous

Hell Creek Formation The Hell Creek Formation is an intensively studied division of mostly Upper Cretaceous and some lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana. The formation stretches over portions of ...

of Montana. ''The

University of Kansas The University of Kansas (KU) is a public research university with its main campus in Lawrence, Kansas, United States, and several satellite campuses, research and educational centers, medical centers, and classes across the state of Kansas. Tw ...

Science Bulletin'' 51(17):539-563. {{Taxonbar , from=Q650212 Taxa named by John Edward Gray Reptile families Extant Maastrichtian first appearances Symbols of New York (state)