Camarasauridae is a family of
sauropod dinosaurs. Among sauropods, camarasaurids are small to medium-sized, with relatively short necks. They are visually identifiable by a short skull with large nares, and broad, spatulate teeth filling a thick jaw.
[1. Weishampel, D. B., Dodson, P., & Osmólska, H. (Eds.). (1990). ''The dinosauria''. Univ of California Press.] Based on cervical vertebrae and cervical rib biomechanics, camarasaurids most likely moved their necks in a vertical, rather than horizontal, sweeping motion, in contrast to most diplodocids.
Taxonomy
Camarasauridae was named by
Edward Drinker Cope
Edward Drinker Cope (July 28, 1840 – April 12, 1897) was an American zoologist, paleontologist, comparative anatomist, herpetologist, and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy intereste ...
in 1877. Its
type genus
In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name.
Zoological nomenclature
According to the International Code of Zoological Nomenclature, "The name-bearing type of a nomina ...
is ''
Camarasaurus'', and it is defined as the clade containing all species more closely related to ''
Camarasaurus supremus'' than ''
Saltasaurus loricatus''.
Phylogenetic relationships
Camarasauridae is typically regarded as belonging to
Macronaria, one of the two major branches of
Neosauropoda. Within Macronaria, it occupies a
basal
Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''.
Science
* Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure
* Basal (medicine), a minimal level that is nec ...
position, outside of
Titanosauriformes. However, some studies have found Camarasauridae to lie outside Neosauropoda.
Members
''Camarasaurus'' is the only taxon uncontroversially regarded as a valid genus of camarasaurid. It contains four species: ''
C. grandis'', ''
C. lentus'', ''
C. lewisi'', and ''
C. supremus''. ''C. lewisi'' may represent a distinct genus, ''Cathetosaurus''.
''
Lourinhasaurus'', the type species of which was formerly assigned to ''Camarasaurus'', is regarded as a camarasaurid by most studies,
though it has also been considered to be a basal eusauropod.
''
Oplosaurus'', from the
Early Cretaceous
The Early Cretaceous (geochronological name) or the Lower Cretaceous ( chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma.
Geology
Pr ...
of the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...
, has been suggested to be a camarasaurid,
but as it is only known from a tooth, its position within Eusauropoda is difficult to determine.
''
Tehuelchesaurus
''Tehuelchesaurus'' () is a genus of dinosaur. It is named in honor of the Tehuelche people, native to the Argentinian province of Chubut, where it was first found.
Description
It was a moderately large (possibly long) cetiosaur-like sauro ...
'', from the Late Jurassic of
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, t ...
, has been considered a camarasaurid in some studies,
but a wide range of other phylogenetic positions have been proposed, including a close relationship to ''
Omeisaurus'',
a position in
Turiasauria,
or as a non-camarasaurid basal macronarian.
''
Bellusaurus'', which is only known from juvenile remains, may be a camarasaurid,
though it has also been considered a basal macronarian, turiasaur, or mamenchisaurid.
A possible camarasaurid of indeterminate genus and species was reported from the
Middle Jurassic of
India
India, officially the Republic of India ( Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the ...
.
Former members
In 1970, Rodney Steel took an expansive concept of Camarasauridae, encompassing all sauropods then known except diplodocoids and titanosaurs.
In 1990, John S. McIntosh regarded Camarasauridae as made up of two subfamilies: Camarasaurinae, containing ''Camarasaurus'', ''Aragosaurus'', ''Euhelopus'', and ''Tienshanosaurus'', and Opisthocoelicaudiinae, containing ''Opisthocoelicaudia'' and ''Chondrosteosaurus''.
''
Dashanpusaurus'', from the Middle Jurassic of China, was originally described as a camarasaurid,
but was subsequently found to be a basal macronarian by phylogenetic analysis.
Diagnostic characters
Several skeletal features have been used to characterize the camarasaurids. In the skull, these include an external narial diameter approximately 40% of the long-axis length of the skull, an arched internarial bar, a short muzzle anterior to the nares, and maxillary shelf.
In the rest of the axial skeleton, these include flat ventral faces on the cervical vertebrae, a triangular flare to the neural spines of the middle and posterior dorsal vertebrae, and a concave posterior surface to the anterior thoracic ribs, as well as an external haemal canal across the anterior vertebrae of the tail.
[Wilson, J. A., & Sereno, P. C. (1998). Early evolution and higher-level phylogeny of sauropod dinosaurs. ''Journal of Vertebrate Paleontology'', ''18''(S2), 1-79.] A reduction to two carpals, long metacarpals relative to the radius, and a twisted ischial shaft serve to identify the appendicular skeleton.
Palaeobiogeography
Broadly speaking, camarasaurids occupied a distribution limited to the
Laurasian continent during the
Upper Jurassic.
Most currently accepted camarasaurid specimens have been discovered in the
Morrison Formation of North America, however some specimens from the African
Tendaguru Formation have been speculated to belong to the genus ''Camarasaurus'', and the closely related ''Lourinhasaurus'' was found in Portugal.
[Raath, J. S. (1987). Sauropod dinosaurs from the Central Zambezi Valley, Zimbabwe, and the age of the Kadzi Formation. ''South African Journal of Geology'', ''90''(2), 107-119.]
References
{{Portal bar, Dinosaurs, Cretaceous
Late Jurassic first appearances
Early Cretaceous extinctions
Macronarians
Taxa named by Edward Drinker Cope
Prehistoric dinosaur families