Camarasaurus, “the chambered lizard”, was a sauropod dinosaur from the Morrison Formation of western North America, dated to the late Jurassic Period about 155 to 145 million years ago. The animal gets its name from the numerous openings within its skull. Camarasaurus belonged to a group of sauropods called the “macronarians” which means “large nostrils”. As such, Camarasaurus was more closely related to Brachiosaurus than to the “diplodocid” sauropods like the eponymous Diplodocus and its relatives.

The Morrison Formation was home to numerous sauropod species, including Apatosaurus, Barosaurus, Brachiosaurus, Diplodocus, and Haplocanthosaurus. Some of these names might be more familiar to the ear. However, in terms of sheer population numbers, Camarasaurus tops the list. More skeletons of Camarasaurus have been found within the Morrison Formation than any other sauropod, and this has led scientists to claim that it was therefore the most common sauropod dinosaur alive during that time.

There are currently three species of Camarasaurus known from the late Jurassic rocks of North America: Camarasaurus grandis, Camarasaurus lentus, and Camarasaurus supremus. Camarasaurus grandis was the oldest of the three, being found in the early and middle stages of the Morrison Formation, about 155-150 MYA. After this appeared Camarasaurus lentus, which is found only within the middle layers of the Morrison; C. grandis and C. lentus co-existed with each other for a time. Finally, both species were replaced by Camarasaurus supremus, the largest of the three species, and it also was alive during the last stages of the Morrison Formation, about 150 -145 MYA. Of these three species, we have more fossils from C. lentus than from the other two.

As far as size goes, Camarasaurus was a tad on the small side for a sauropod. Both Camarasaurus grandis and Camarasaurus lentus measured only 50 feet long. The largest of the three species, Camarasaurus supremus, possibly measured 70 to 75 feet long, but this is only an estimate since no complete adult skeleton of C. supremus has been found yet. Most sources which I have read give a maximum size of 60 feet. However, I ought to state that this might just be an size measurement average between the two numbers seen above, especially since most of these sources do not differentiate between the three separate species but lump all of them together as if they were just one.

Camarasaurus‘ relatively small size (that is, compared with the other larger sauropods that it shared its habitat with) and meaty build likely made it one of the preferred targets for a mob of Allosaurus to take down. The reason why Camarasaurus was the most common species of its kind might be due partly to its smaller-than-average size (smaller stomachs mean more food to go around for everyone, and by extent leads to having larger populations) and partly to its apparently generalist diet. Creatures which have a specialized diet are often hit hard when catastrophes arise, whereas dinosaurs that are more adaptable and flexible in terms of what they eat come out more favorably.

Note: The original drawing that was posted to this article, which was dated to August 5, 2012, was removed because it was anatomically inaccurate and in general was of poor quality. The drawing that you see below is an updated version.

Camarasaurus supremus. © Jason R. Abdale. April 18, 2021.

Many times, you’ll see these dinosaurs illustrated Gregory Paul-style, with thin spindly legs. I decided that the biomechanics of this simply weren’t feasible, and so I gave my animal suitably thicker more elephant-like legs, able to hold up the tens of tons of weight. Also notice that, contrary to other artistic renderings of this species, the neck is NOT held straight vertically upright, but is thrust more forwards in a 45 degree S-shaped curve. In terms of the color pattern, I’ve always imagined Camarasaurus colored in the scheme that you see above, even as a little kid – tan body with broad brown stripes and a somewhat yellowish-tan underbelly. I simply cannot imagine this species colored in any other way. Whether or not Camarasaurus really was colored in this fashion, we’ll probably never know. The two drawings that you see above were made with No. 2 pencil and assorted colored pencils.

Keep your pencils sharp, people.

Categories: Paleontology, Uncategorized

Tags: allosaurid, Allosaurus, America, Apatosaurus, art, Camarasaurus, dinosaur, Diplodocus, Jurassic Period, Late Jurassic, Macronaria, macronarian, Mesozoic, Morrison Formation, North America, paleo-art, paleontology, reptile, sauropod, theropod