Camarasauridae

Camarasauridae (meaning "chambered lizards") is a family of neosauropod dinosaurs within the clade Macronaria, the sister group to Titanosauriformes. 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. 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. Cladistically, they are defined to be all sauropods more closely related to Camarasaurus supremus than to Saltasaurus loricatus.

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. 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.

References

Category:Late Jurassic first appearances
Category:Tithonian taxonomic families
Category:Berriasian taxonomic families
Category:Early Cretaceous extinctions
Category:Macronarians
Category:Taxa named by Edward Drinker Cope