Cearachelys
Encyclopedia
Cearachelys is an extinct genus
of pleurodira
n turtle
which existed some 80-million years ago. The genus is monotypic
, with only type species
Cearachelys placidoi known.
The genus was named for Ceará
, the Brazilian state where the species was discovered. The specific name on the other hand was named after Placido Nuvens, a director of the Museu Paleontologico de Santana do Cariri.
In 2001, the remains of two mostly complete turtle skeletons from the Early Cretaceous
rocks of the Santana Formation
were used to describe Cearachelys placidoi. Both specimens were from the Romualdo Member of the formation in what is now Northwestern Brazil
. The type specimen, tentatively labeled MPSC-uncatalogued (for the Museu Paleontologico de Santana do Cariri where the specimen resides), consisted of an incomplete skull, the turtle’s shell, a few neck vertebrae and some limb bone fragments. The second specimen, TUTg 1798 is a more complete fossil consisting of most of the turtle's axial and appendicular skeleton. While this specimen hails from the same locality, it was actually procured by the museum 8 years prior, in 1993. A fragmentary third specimen was identified in 2007 as belonging to C. placidoi. The specimen, MN-6760-V consisted of a rather complete fossilized carapace
and plastron measuring some 20 centimeters long.
The species was identified as a pleurodire
based on a number of distinguishing anatomical characteristics – mainly the arrangement of skeletal elements in its skull and the attachment of its pelvic girdle to its carapace. Further analysis of C. placidois skull elements led to its classification in the family Bothremydidae
. However, skull elements also differentiate the species from the other members of its family. Its closest relation seems to be from a taxon that evolved much later, the Late Cretaceous
turtle Galianemys from Morocco
. Both genera
possess a rather retracted jugal
bone, a characteristic not seen in other bothremydids. In a 2006 paper on the phylogeny of extinct pleurodires, Gaffney united the two closely related genera in the tribe
Cearachelyini.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of pleurodira
Pleurodira
The Pleurodira are one of the two living suborders of turtles, the other being the Cryptodira. In many cases in the nomenclature of animals, ranks such as suborder are considered of little importance apart from nomenclatural or taxonomic reasons. However, this is not the case with the suborders of...
n turtle
Turtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
which existed some 80-million years ago. The genus is monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
, with only type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
Cearachelys placidoi known.
The genus was named for Ceará
Ceará
Ceará is one of the 27 states of Brazil, located in the northeastern part of the country, on the Atlantic coast. It is currently the 8th largest Brazilian State by population and the 17th by area. It is also one of the main touristic destinations in Brazil. The state capital is the city of...
, the Brazilian state where the species was discovered. The specific name on the other hand was named after Placido Nuvens, a director of the Museu Paleontologico de Santana do Cariri.
In 2001, the remains of two mostly complete turtle skeletons from the Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
rocks of the Santana Formation
Santana Formation
The Santana Formation is a geologic Lagerstätte in northeastern Brazil's Araripe Basin where the states of Pernambuco, Piauí and Ceará come together. The geological formation, named after the village of Santana do Cariri, lies at the base of the Araripe Plateau...
were used to describe Cearachelys placidoi. Both specimens were from the Romualdo Member of the formation in what is now Northwestern Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
. The type specimen, tentatively labeled MPSC-uncatalogued (for the Museu Paleontologico de Santana do Cariri where the specimen resides), consisted of an incomplete skull, the turtle’s shell, a few neck vertebrae and some limb bone fragments. The second specimen, TUTg 1798 is a more complete fossil consisting of most of the turtle's axial and appendicular skeleton. While this specimen hails from the same locality, it was actually procured by the museum 8 years prior, in 1993. A fragmentary third specimen was identified in 2007 as belonging to C. placidoi. The specimen, MN-6760-V consisted of a rather complete fossilized carapace
Carapace
A carapace is a dorsal 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 underside is called the plastron.-Crustaceans:In crustaceans, the...
and plastron measuring some 20 centimeters long.
The species was identified as a pleurodire
Pleurodira
The Pleurodira are one of the two living suborders of turtles, the other being the Cryptodira. In many cases in the nomenclature of animals, ranks such as suborder are considered of little importance apart from nomenclatural or taxonomic reasons. However, this is not the case with the suborders of...
based on a number of distinguishing anatomical characteristics – mainly the arrangement of skeletal elements in its skull and the attachment of its pelvic girdle to its carapace. Further analysis of C. placidois skull elements led to its classification in the family Bothremydidae
Bothremydidae
Bothremydidae is an extinct family of side-necked turtle. They belong to sub-order Pleurodira and order Testudines. Bothremydidae lived in fresh water and were amphibious. They were actively mobile omnivores.-Taxonomy:...
. However, skull elements also differentiate the species from the other members of its family. Its closest relation seems to be from a taxon that evolved much later, the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
turtle Galianemys from Morocco
Morocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...
. Both genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
possess a rather retracted jugal
Jugal
The jugal is a skull bone found in most reptiles, amphibians, and birds. In mammals, the jugal is often called the malar or Zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species....
bone, a characteristic not seen in other bothremydids. In a 2006 paper on the phylogeny of extinct pleurodires, Gaffney united the two closely related genera in the tribe
Tribe (biology)
In biology, a tribe is a taxonomic rank between family and genus. It is sometimes subdivided into subtribes.Some examples include the tribes: Canini, Acalypheae, Hominini, Bombini, and Antidesmeae.-See also:* Biological classification* Rank...
Cearachelyini.