Profile of Camarasaurus

True heavyweights like Brachiosaurus and Apatosaurus get all the press, but pound for pound, the most common sauropod of late Jurassic North America was Camarasaurus. This medium-sized plant-eater, which weighed only about 20 tons (compared to near 100 tons for the largest sauropods and titanosaurs), is believed to have roamed the western plains in sizable herds, and its juveniles, aged and ailing were probably a prime source of food for the hungry theropods of its day (the most likely antagonist being Allosaurus). Name: Camarasaurus (Greek for chambered lizard); pronounced cam-AH-rah-SORE-us Habitat: Plains of North America Historical Period: Late Jurassic (150-145 million years ago) Size and Weight: About 60 feet long and 20 tons Diet: Plants Distinguishing Characteristics: Large, boxy skull; hollow vertebrae; single claw on front feet Paleontologists believe that Camarasaurus subsisted on more challenging fare than its larger sauropod cousins since its teeth were adapted to slicing and shredding especially tough vegetation. Like other plant-eating dinosaurs, Camarasaurus may also have swallowed small stones--called gastroliths--to help grind down food in its massive gut, though direct evidence for this is lacking. (By the way, this dinosaurs name, Greek for chambered lizard, refers not to the stomach of Camarasaurus but to its head, which contained numerous large openings that probably served some kind of cooling function.) Does the unusual prevalence of Camarasaurus specimens (especially in the stretch of the Morrison Formation spanning Colorado, Wyoming, and Utah) mean that this sauropod vastly outnumbered its more famous relatives? Not necessarily: for one thing, just because a given dinosaur happens to persist in the fossil record speaks more about the vagaries of the preservation process than the size of its population. On the other hand, it only makes sense that the western U.S. could support a larger population of medium-sized sauropods, compared to smaller herds of 50- and 75-ton behemoths, so Camarasaurus may well have outnumbered the likes Apatosaurus and Diplodocus. The first fossil specimens of Camarasaurus were discovered in Colorado, in 1877, and quickly purchased by the famous American paleontologist Edward Drinker Cope (who was probably afraid that his arch-rival Othniel C. Marsh would beat him to the prize). It was Cope who had the honor of naming Camarasaurus, but that didnt prevent Marsh from bestowing the genus name Morosaurus on some very similar specimens he discovered later (and which turned out to be synonymous with the already-named Camarasaurus, which is why you wont find Morosaurus on any modern lists of dinosaurs). Interestingly, the profusion of Camarasaurus fossils has allowed paleontologists to investigate this dinosaurs pathology--the various diseases, ailments, wounds and contusions that all dinosaurs suffered at one time or another during the Mesozoic Era. For example, one pelvic bone bears evidence of an Allosaurus bite mark (its not known whether or not this individual survived this attack), and another fossil shows possible signs of arthritis (which may or may not, as in human beings, have been an indication that this dinosaur reached old age).