Cratochelone
Encyclopedia
Cratochelone is an extinct genus
of sea turtle
in the family Protostegidae
and containing a single
species Cratochelone berneyi. The species is known only from the mid to late Albian
Toolebuc Formation
, part of the rolling downs group, in the Hughenden
of Central northern Queensland
, Australia.
, specimen number "QM F14550". The specimen is composed of a grouping of disassociated post-cranial skeleton elements in a hard, fine-grained and "dirty-stone colored" sedimentary matrix. The bones include portions of the left side plastron, the shoulder girdle, and segments of a forelimb. The fossil is thought to have been recovered by F. L. Berney from outcrops of the Toolebuc Formation exposed in the Eromanga Basin
. The type specimen is currently preserved in the paleontology
collections housed in the Queensland Museum
, in Brisbane
, Australia. Cratochelone was first studied by Herber A. Longman, husband of Irene Longman
, of the Queensland Museum. Longman's 1915 type description of the genus and species was published in the Memoirs of the Queensland Museum. The generic
name was coined by Longman to be a contradistinction of the related Albian genus Notochelone
also described from Queensland. The specific epithet
berneyi is in honor of F. L. Berney who recovered and donated the specimen to the museum.
Cratochelone bernedi is one of three protostegid sea turtle taxa described from the fossil record of Australia. Described in 1885 Notochelone costata
is the smallest species, while the most recently described species Bouliachelys suteri, is between Notochelone and Cratochelone in size.
In his type description Longman noted the incomplete nature of the fossil and hoped that more complete specimens would be found. Despite this, the type specimen remains the only known specimen of the species.
, ulna
and humerus
. Though missing, the shaft of the humerus was similar to those found in primitive protostegid species. The wide angle of divergence between the scapular processes is similar to a number of early protostegid and cheloniids
. The wide wings along the entoplastron and its lack of fusion with the surrounding bones indicates that Longman's placement of the genus is accurate. Longman noted the very large size of the bones, and estimated a complete specimen may have reached close to 4 metres (13.1 ft). This size was regarded as dubious by later researchers and was recorded several times as 2 metres (6.6 ft). Within his re-description of the type material in 2006, Benjamin Kear reaffirmed the size of full specimens to be in the 4 metres (13.1 ft) range.
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 sea turtle
Sea turtle
Sea turtles are marine reptiles that inhabit all of the world's oceans except the Arctic.-Distribution:...
in the family Protostegidae
Protostegidae
Protostegidae is a family of extinct marine turtles that lived during the Mesozoic Era. The family includes some of the largest sea turtles that ever existed. The largest, Archelon, had a head a meter long...
and containing a single
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...
species Cratochelone berneyi. The species is known only from the mid to late Albian
Albian
The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series. Its approximate time range is 112.0 ± 1.0 Ma to 99.6 ± 0.9 Ma...
Toolebuc Formation
Toolebuc Formation
The Toolebuc Formation is a geological formation in Queensland, Australia whose strata date back to the Early Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.-Vertebrate paleofauna:...
, part of the rolling downs group, in the Hughenden
Hughenden
Hughenden may refer to:*Hughenden, Queensland, a town in Australia*Hughenden, Alberta, a village in central Alberta, Canada*Hughenden Valley, a village in Buckinghamshire, England*Hughenden Manor, a mansion in High Wycombe, Buckinghamshire, England...
of Central northern Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
, Australia.
History and classification
Cratochelone berneyi is known only from one fossil, the holotypeHolotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
, specimen number "QM F14550". The specimen is composed of a grouping of disassociated post-cranial skeleton elements in a hard, fine-grained and "dirty-stone colored" sedimentary matrix. The bones include portions of the left side plastron, the shoulder girdle, and segments of a forelimb. The fossil is thought to have been recovered by F. L. Berney from outcrops of the Toolebuc Formation exposed in the Eromanga Basin
Eromanga Basin
The Eromanga Basin is a large Mesozoic sedimentary basin in central and northern Australia. It covers parts of Queensland, the Northern Territory, South Australia, and New South Wales, and is a major component of the Great Artesian Basin...
. The type specimen is currently preserved in the paleontology
Paleontology
Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...
collections housed in the Queensland Museum
Queensland Museum
The Queensland Museum is the state museum of Queensland. The museum currently operates four separate campuses; at South Brisbane, Ipswich, Toowoomba and Townsville.The museum is funded by the State Government of Queensland.-History:...
, in Brisbane
Brisbane
Brisbane is the capital and most populous city in the Australian state of Queensland and the third most populous city in Australia. Brisbane's metropolitan area has a population of over 2 million, and the South East Queensland urban conurbation, centred around Brisbane, encompasses a population of...
, Australia. Cratochelone was first studied by Herber A. Longman, husband of Irene Longman
Irene Longman
Irene Maud Longman was a female Queensland politician. She was the first woman to stand and be elected to the Queensland Parliament....
, of the Queensland Museum. Longman's 1915 type description of the genus and species was published in the Memoirs of the Queensland Museum. The generic
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...
name was coined by Longman to be a contradistinction of the related Albian genus Notochelone
Notochelone
Notochelone is an extinct genus of sea turtle, which existed about 100 million years ago. The species was first described by Richard Lydekker in 1889. It was the most common marine reptile living in the inlands of the sea around Queensland, Australia. It was a small turtle, and was about the same...
also described from Queensland. The specific epithet
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
berneyi is in honor of F. L. Berney who recovered and donated the specimen to the museum.
Cratochelone bernedi is one of three protostegid sea turtle taxa described from the fossil record of Australia. Described in 1885 Notochelone costata
Notochelone
Notochelone is an extinct genus of sea turtle, which existed about 100 million years ago. The species was first described by Richard Lydekker in 1889. It was the most common marine reptile living in the inlands of the sea around Queensland, Australia. It was a small turtle, and was about the same...
is the smallest species, while the most recently described species Bouliachelys suteri, is between Notochelone and Cratochelone in size.
In his type description Longman noted the incomplete nature of the fossil and hoped that more complete specimens would be found. Despite this, the type specimen remains the only known specimen of the species.
Description
The holotype specimen's forelimb is represented by the proximal ends of the radiusRadius
In classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter. If the object does not have an obvious center, the term may refer to its...
, ulna
Ulna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...
and humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
. Though missing, the shaft of the humerus was similar to those found in primitive protostegid species. The wide angle of divergence between the scapular processes is similar to a number of early protostegid and cheloniids
Cheloniidae
Cheloniidae is a family of turtles belonging to the sea turtle superfamily Chelonioidea.-Extant genera:*Genus Caretta**Loggerhead sea turtle *Genus Chelonia**Green sea turtle *Genus Eretmochelys...
. The wide wings along the entoplastron and its lack of fusion with the surrounding bones indicates that Longman's placement of the genus is accurate. Longman noted the very large size of the bones, and estimated a complete specimen may have reached close to 4 metres (13.1 ft). This size was regarded as dubious by later researchers and was recorded several times as 2 metres (6.6 ft). Within his re-description of the type material in 2006, Benjamin Kear reaffirmed the size of full specimens to be in the 4 metres (13.1 ft) range.