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Apatosaurus

Apatosaurus, formerly known as Brontosaurus (erroneously named Brontosaurus by Othniel Charles Marsh after he incorrectly placed the head of a Camarasaurus on the body of an Apatosaurus), is a genus of sauropod dinosaurs that lived about 140 million years ago, during the Jurassic period. They were some of the major land animals that ever existed, about 4.5 meters (15 feet) tall at the hips, with a length of up to 25m (80 feet) and a mass up to 35 metric tones (40 tons). However, the Argentinosaurus was even larger.

The cervical vertebra and the bones in the legs were larger and heavier than that of Diplodocus, but they both had the long neck and tail. The skull was first recognized in 1975, a century after it got its name. The Apatosaurus had a claw on its hand, but only the thumb. Scientists have a theory about the tail being lifted perhaps a meter above the ground. It would prevent the dinosaur from stomping on it, and put the tail out of arrive at of predators.

Environment Early on, it was believed that Apatosaurus was too massive to support its own weight on dry land, so it was theorized that the sauropod must have lived partly submerged in water, perhaps in a swamp. Recent conclusion does not support this. In fact, like its relative Diplodocus, Apatosaurus was a grazing animal with a very long neck, and a long tail that served as a counterweight. Fossilized footprints indicate that it probably lived in herds. To aid in dispensation food, Apatosaurus may have swallowed gizzard stones (gastroliths) the same way many birds do today — its jaws alone were not sufficient to chew tough plant fibers.

The Apatosaurs perhaps lumbered along in flocks on riverbanks with trees, eating off the top leaves. Scientists believe that these sauropods could not raise their neck to an angle of 90 degrees, as doing so would sluggish blood flow to the brain excessively; blood starting at the body proper would take two or more minutes to reach the brain. Furthermore, studies of the arrangement of the neck vertebrae have revealed that the neck was not as flexible as previously thought. No one knows how Apatosaurs ate enough food to gratify their enormous bodies. They probably ate constantly, pausing only to cool off, drink or to remove parasites. They must have slept standing upright. If attacked by a predator, it could preserve itself by swinging its tail from side to side, or stomp at the meat-eater. Because of the Apatosaurs’ slow velocity, they lived in herds, and they could "call" on each other, if one needed help.

Classification and history

In 1877, Othniel Charles Marsh available notes on his discovery of the Apatosaurus, and then in 1879 described one more, more complete dinosaur — the Brontosaurus. In 1903, it was discovered that the apatosaur was in fact a juvenile brontosaur, and the name Apatosaurus, having been published first, was deemed to have priority as the bureaucrat name; Brontosaurus was relegated to being a synonym. The name was not formally removed from the records of paleontology until 1974.

Fossils of this animal have been establish in Nine Mile Quarry and Bone Cabin Quarry in Wyoming, and at sites in Colorado, Oklahoma, Utah, USA.

Species

A. Ajax is the type species of the genera, and was named by the paleontologist Othniel Charles Marsh in 1877 after Ajax, the hero from Greek mythology. It is the holotype for the genera, and two partial skeletons have been found including part of a skull.

A. Excelsus (originally Brontosaurus) was named by Marsh in 1879. It is known from six partial skeletons, including part of a skull, which have been establish in the United States, in Oklahoma, Utah, and Wyoming.
A. louisae was named by William Holland, in 1915. It is known from one incomplete skeleton, which was found in Colorado, in the United States.

Robert T. Bakker made A. yahnahpin the type species of a new genus, Eobrontosaurus in 1998, so it is now correctly Eobrontosaurus yahnahpin. Filla, James and Redman named it in 1994. One partial skeleton has been found in Wyoming.