fact file

Pronounced: ka-MAR-a-SORE-us

Name means: Chambered Reptile


Species: grandis, lentus, supremis

Range: Late Jurassic (Tithonian, 150-145 MYA) from Utah, Wyoming, Colorado, South Dakota, Montana, New Mexico, and Oklahoma, possibly Germany, Portugal, Russia, and Zimbabwe

Size estimate: 50-75 ft length, 40-50 tons

Discovery: Edward Drinker Cope, 1877

Classification: dinosauria, saurischia, sauropoda, macronaria, camarasauridae


Camarasaurus ranks among the most common dinosaurs ever found. Scientists have several explanations for its abundance. One suggests it may have lived in areas favorable for fossilization. Scientists call this condition “preservation bias.” Many of the sites that have produced Camarasaurus fossils formed from moving water. Water covers bones quickly and often results in better preservation. However, Camarasaurus may also have reached greater numbers than other animals in its environment. The secret to this success might stem from its feeding method. It may have included a greater variety of plants in its diet than other sauropods because its neck featured greater flexibility, allowing it to feed at different levels. Joints in its tail may have let it rear up to take advantage of higher branches. Tooth wear reveals that it chewed its food—an odd feature for a sauropod from Jurassic North America.


The name “Camarasaurus” refers to chambers in its backbones called pleurocoels (PLUR-o-seels). These pleurocoels aren’t unique to Camarasaurus, but it was one of the first dinosaurs shown to have them. Scientists originally believed they made the backbones lighter. Recent studies propose they also housed air sacs that connected to the animal’s lungs, like a bird’s respiratory system.


This sculpture portrays a young Camarasaurus.  When scientists first found this genus, they had not yet figured out how to tell young animals apart from adults. They thought that Camarasaurus did not grow as large as other sauropods, but most of those first finds really had not reached full size yet.  A full size for the largest and latest species, Camarasaurus supremis, reached as long as 75 feet and over 50 tons in weight.