Camarasaurus is by far one of the most numerous sauropods discovered and is one of the few dinosaurs we know what all the bones looked liked. It also held a small, but key role in the changing of the name Brontosaurus to Apatosaurus !
The most famous Camarasaurus skeleton is the 3-meter long Camarasaurus lentus (which can be seen at the National Dinosaur Museum ). Remarkably this animal had grown that large in only two years, having hatched from an egg no bigger then a soccer ball! The young Camarasaurus upon reaching its eighth year would then be fully-grown adult; roughly 18 metres long from head to tail and weighed around 35 tonnes.
It is unsure why dinosaurs grew so fast. Possibly they did it for protection- the larger you are; the safer you are from predators. Or perhaps they migrated. To migrate you have to grow fast or, as a small child, you may never survive your first, long march. As there is a growing amount of evidence towards large dinosaurs migrating (discussed later in this article), this is probably the most likely answer.
This ‘baby' Camarasaurus lentus skeleton was found encased in a minuet layer of carbon. It is thought this carbon is the decomposed remains of the animal's skin and soft tissues. This, along with the nearly complete skeleton, suggests this particular specimen was buried extremely quickly, never allowing the usual decomposition of the soft body parts that is found in other dinosaur skeletons. Possibly it was caught in a flash flood and drowned, its corpse quickly buried by the churning rivers sandy floor.
The first Camarasaurus was discovered in 1877, and was named by Edward.D.Cope. Though only a few bones were initially found, Cope named his sauropod Camarasaurus supremes . Because of other finds in the area, Cope assumed his dinosaur lived during the late Jurassic period.
During December of that same year, Cope's long time adversary, O.C.Marsh, named two sauropods from various remains he was studying. The first, and smaller one he named Apatosaurus grandis . The second, larger fossil, he named Apatosaurus ajax (more on this later).
Over the next 50 years, many other sauropod remains were found across the globe, including Morosaurus robustus, Morosaurus impar, Caulodon leptognasus , Caulodon diversiderns and Uintasaurus douglassi . All were misnamed and are now recognized as Camarasaurus 's.
For some time Camarasaurs were though to be closely related to Diplodocus , another late Jurassic sauropod. But an inspection of the African Brachiosaurus seemed to show they also shared several features with that monster of the Jurassic as well. Could Camarasaurus be a link between the two as it shared common features of both? This is now considered unlikely as the length of a Camarasaurs neck and tail when compared to those found on Apatosaurus and Diplodocus are much smaller. A Camarasaurus only has 50 bones in its tail while Apatosaurus has 82. Camarasaurus is also a very common in the fossil record while Diplodocus and Apatosaurus are extremely rare (suggesting they lived a more solitary life style- though it may also suggest they simply lived in areas that was not kind to the production of fossils).
Much like Brachiosaurus , Camarasaurus had a short tail and neck, and it's front legs were slightly longer then its rear ones (a feature of true Brachiosaurs ). Also, Camarasaurus has its nostrils and eye sockets high upon its head, leading some paleontologists to believe they lived an aquatic lifestyle. The placement of the nostrils may have allowed them to breath while the rest of their body was submerged (and supported) in deep water. However, recent tests have shown this is physically impossible. A Brachiosaur/Camarasaurus standing in water deep enough to cover its head would have been so deep, the water pressure would have been so great that the sauropods lungs would have been crushed or at the very least greatly hindered for breathing.
Another recent theory suggests the Brachiosaur / Camarasaurus's high nostrils are features that can be found on one other large land animal, the elephant! Is it possible, like the elephant, Brachiosaurus and Camarasaurus possessed long, flexible trunks? Again this is unlikely as careful study of sauropod skulls reveals they possessed no facial muscles; an important item if you own a long, heavy trunk that you want to move about!
And as for the Camarasaurus/Brachiosaurus connection? The longer front legs on Camarasaurus only superficially resemble those found on Brachiosaurus , and the enlarged nasal passages might simply be to help lighten such a large skull (large for sauropods anyway) implying rather then being closely related, these two sauropods seem to have developed several similar features (called convergent evolution!).
Another feature of Camarasaurus skulls are the large, tough teeth they possess. These, as well as the various gastroliths (stomach stones that are swallowed and crushed together to help animals digest- a feature found in several modern birds and crocodiles), suggest they were eating very tough, fibrous plants. A stark contrast to the thin, peg like teeth of Diplodocus . Both animals' teeth tell us they were eating completely different plants, allowing them to possibly live side by side as the two animals would never have competed for the same food.
Fossilized track ways have also shown that several of these enormous creatures were indeed traveling together going a long way to proving Sauropods like Camarasaurus were indeed migrating, possibly even in mixed herds (as seen with herbivores in Africa today). Seasonal flooding, long dry seasons and the absence of fast growing plants like grass also point to these animals having to migrate to survive. If a large herd or family group stayed in one area for too long they would quickly strip the area of all vegetation. Even elephants in modern Africa (which possesses extremely fast growing grass) are continually on the move as they can defoliate a region in a matter of weeks, forcing them to move on. And elephants are nowhere near the size of an adult Camarasaurus !
Though the fossil record shows Camarasaurs were one of the more numerous sauropods, it was originally thought they were even more successful then we currently believe! Sauropod remains all across the world, including finds such as Euhelopus from china, Opisthocoelicaudia from Mongolia , along with several others in Europe , were all originally identified as Camarasaurus . Close study showed they all had enough individual features to suggest that, though closely related to Camarasaurus , they were infact new species, thus all were placed under a new family name, the Camarasauridae.
Euhelopus is extremely similar in many ways to Camarasaurus . At 15 metres, it is smaller then Camarasaurus , yet it possessed similar teeth and nasal passages in it's skull. Euhelopus however had a much longer snout then Camarasaurus whose skull was very wide and flat, much like a bulldog.
Opisthocoelicaudia is only 12 metres long and the one good specimen on record is completely missing its head and neck, yet the rest of the body is pure Camarasaurus except for one thing. The name Opisthocoelicaudia means 'hollow bones at the back' after the fact that this sauropod had the hollowed spaces in its tail vertebrae (which all sauropods possessed) at the back of the vertebrae, while all other sauropods had their hollow spaces at the front. This was thought to be just a unique feature of this particular sauropod, and never stopped paleontologists from thinking it was a Camarasaurid!
It is now known they were completely wrong! All these dinosaurs are actually Titanosaurids; the most globally diverse of all the sauropods (indeed of almost all mega dinosaur species). For instance the head of Opisthocoelicaudia had actually been found, some distance from the rest of the body and had simply thought to belong to another sauropod. This head in no way resembles those found on Camarasaurus's !
As for Camarasaurus's role in invalidating the name Brontosaurus , well the exact same thing happened as it did with Opisthocoelicaudia . The original Brontosaurus skeleton unearthed in the 19 th century was headless, yet a skull was found only a short distance away. Assuming this skull belonged to the Brontosaurus, scientists whacked it on the body, creating the blunt snouted Brontosaurus ! The head as you've probably guessed did not belong to the Brontosaur , but a Camarasaurus , and after nearly 100 years, the head had to be replaced! With the loss of its head, the rest of the skeleton clearly belonged to Apatosaurus , a sauropod named some months before Brontosaurus . Thus under scientific naming laws, the great 'Thunder lizard' had to revert back to its original name. A search through the records of the time revealed that a skull had been found with the Apatosaurus skeleton, and was thought to belong to a Diplodocus that was also found nearby. This skull fit perfectly on the Apatosaurus skeleton! (It is also now recognized that there was no Diplodocus found in the area but a juvenile, or perhaps female Apatosaurus ) We now know Apatosaurus had an elongated head, more like Diplodocus then the pug faced Camarasaurus.
It would seem the more we learn the more we have to relearn when dealing with the ever-changing science of paleontology!