Camarasaurus

Type Species: Camarasaurus supremus  

Classification: Dinosauria – Saurischia – Sauropoda - Gravisauria - Eusauropoda - Neosauropoda – Macronaria – Camarasauridae 

Time Period: Late Jurassic 

Location: United States 

Diet: Herbivore

Camarasaurus was the most common sauropod of the Morrison Formation; vast herds roamed the floodplains and valleys of Late Jurassic North America. Herding behavior is attested in the fossil record: a group of two adults and a forty-foot-long juvenile died together around 150 million years ago in what is now Wyoming. It appears their bodies were washed by a flooding river and buried in sediment. This find implies that Camarasaurus traveled in herds or at least in family groups, though the discovery of Camarasaurus eggs laid in lines rather than nests suggests that Camarasaurus didn’t tend to its young. It’s possible that Camarasaurus embraced an R-strategy for survival, in which overwhelming numbers of young were hatched in the hope that some of them made it to adulthood. Juveniles, having survived the many predators of the Morrison Formation, may have ‘linked in’ with roving herds for safety. The size of herds is pure speculation, for unlike some ceratopsians of the Cretaceous, vast Camarasaurus bone-beds haven’t been discovered. 

Camarasaurus could grow up to sixty feet in length, though some specimens reached up to seventy-five feet. Skeletal studies indicate that these sauropods reached sexual maturity around twenty years of age. Camarasaurus had a blunt, box-like head that, despite its bulldog appearance, was filled with lots of air cavities (called fenestrae) which helped lighten the skull’s weight. Its teeth were seven and a half inches long, and they were stronger than those of most sauropods. These sturdy, spoon-like, deep-rooted teeth extended nearly into the cheeks, in contrast with the front-only teeth of some sauropods such as Diplodocus. Studies on the plentiful teeth have revealed that they were used vigorously in chewing and were replaced on average every two months; the lack of gastrolith fossils in the numerous specimens indicate that Camarasaurus chewed its food down to a pulp prior to swallowing. When scientists performed clumped isotope thermometry on the enamel covering the teeth of several genera of Jurassic sauropods, including Camarasaurus, it revealed temperatures of 90.3-98.4 degrees Fahrenheit, comparable to that of modern mammals. Its neck was held up high so that the head were at a level where Camarasaurus could eat from the tree canopy like its contemporary cousin Brachiosaurus; the numerous fenestrae in its skull would’ve lightened the weight, enabling it to hold it higher off the ground. 

Camarasaurus’ legs were about equal length (the forelegs were only slightly shorter than the hind-legs), unlike Brachiosaurus’ long forelegs and Diplodocus’ longer hind-legs. The fact that its forelegs were slightly shorter than the hind-legs would’ve made its back slope forward, but its high shoulders off-balanced this so that its body ran nearly parallel to the ground. Its neck and tail were relatively short for sauropods, and like most sauropods its inner toe bore a large, sharp claw. Camarasaurus’ name comes from the Greek word for ‘chamber,’ referring to the chambers discovered in its vertebrae. These air-filled cavities made its bones pneumatic, and their purpose has been approached in two ways: the air-filled cavities (pleurocels) may have served to reduce the weight of its skeleton, or they may have even been air sacs that were part of the sauropods’ respiratory system. These features are found in plenty of other sauropods as well as in theropods; it may very well be a common feature of the saurischian lineage that leads to the avian respiratory system in which birds use similar air sacs to increase their breathing potential. If this is the case for Camarasaurus, the air sacs would’ve provided a super-efficient airflow down the long neck so that the fresh air went down one network of sacs whilst oxygen-depleted air went up another. This would result in a constant supply and exchange of breathable air despite the distance of the lungs from the mouth and nostrils.