''Prochelidella'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of Early to

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

chelid

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

s from the Bajo Barreal, Candeleros, Cerro Barcino and Portezuelo Formations of the Cañadón Asfalto, Golfo San Jorge and Neuquén Basins in

Patagonia Patagonia () is a geographical region that includes parts of Argentina and Chile at the southern end of South America. The region includes the southern section of the Andes mountain chain with lakes, fjords, temperate rainforests, and glaciers ...

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

. It includes the following species: * ''P. argentinae'' * '' P. buitreraensis'' * ''P. cerrobarcinae'' * ''P. palomoi'' * ''P. portezuelae'' de la Fuente. 2003. Two new Pleurodiran turtles from the Portezuelo Formation (Upper Cretaceous) of northern Patagonia, Argentina. Journal of Paleontology: Vol. 77, No. 3, pp. 559–575.

''Prochelidella buitreraensis''

''Prochelidella buitreraensis'' is known from the

Huincul Formation The Huincul Formation is a geologic formation of Late Cretaceous (Cenomanian to Turonian, Early Turonian) age of the Neuquén Basin that outcrops in the Mendoza Province, Mendoza, Rio Negro Province, Río Negro and Neuquén Provinces of northern ...

of Argentina. Its

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

references the paleontological site La Buitrera, where its fossils were discovered. The remains are notable for their exceptional state of preservation, which includes the presence of the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

. Besides, the remains of

cervical vertebrae In tetrapods, cervical vertebrae (: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In saurop ...

, the

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses Science Biology * Seashell, a hard outer layer of a marine ani ...

and the

appendicular skeleton The appendicular skeleton is the portion of the vertebrate endoskeleton consisting of the bones, cartilages and ligaments that support the paired appendages ( fins, flippers or limbs). In most terrestrial vertebrates (except snakes, legless li ...

have also been found. The remains were found in Cañadón de las Tortugas, at La Buitrera,

Río Negro Province Río Negro (, ''Black River'') is a province of Argentina, located in northern Patagonia. Neighboring provinces are from the south clockwise Chubut, Neuquén, Mendoza, La Pampa and Buenos Aires. To the east lies the Atlantic Ocean. Its cap ...

, Argentine Patagonia, by scientists from CONICET. The estimated age of the finding, from the

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

age, was calculated with radiometric dating carried out on zircons on a volcanic

tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock co ...

. The remains of ''Prochelydella buitreraensis'' are hosted at Carlos Ameghino Provincial Museum in the city of

Cipolletti Cipolletti ( or ) is a city in north of the Patagonian . With a population of 105 482 inhabitants at the , Cipolletti is the third-most populated settlement in the province, after San Carlos de Bariloche and General Roca. Together, with Neuquén ...

. Its discovery appears to show that turtles and tortoises at some point in their early history were incapable of hiding their heads into their shells.

References

{{Taxonbar, from=Q7247353 Chelidae Fossil chelid turtles Prehistoric turtle genera Cretaceous turtles Albian life Cenomanian life Coniacian life Turonian life Early Cretaceous reptiles of South America Late Cretaceous reptiles of South America Cretaceous Argentina Fossils of Argentina Bajo Barreal Formation Candeleros Formation Cerro Barcino Formation Portezuelo Formation Fossil taxa described in 2001 Prehistoric turtles of South America