Apatosaurus

Apatosaurus ("deceptive lizard") was a sauropod dinosaur that lived in the Late Jurassic of North America. Due to its association with the now-redundant genus "Brontosaurus", it has become one of the most famous dinosaurs known to the general public.

Description
The length of Apatosaurus has usually been estimated at around 23 meters. The dinosaur was stockier than many related genera such as Diplodocus, but recent weight estimates have varied between 16 and 22 tonnes.

Like other sauropods, Apatosaurus had a small head compared to its body, and its mouth was filled with chisel-like teeth. It also possessed a deep chest and very robust bones.

the brontosaurus was registered as a different species in 2015, it is slightly different from the apatosaurus.

Classification
Apatosaurus is part of the taxonomic family Diplodocidae, which also contains the genera Diplodocus, Barosaurus and others.

The type specimen, Apatosaurus ajax, was described and named by Othniel Charles Marsh in 1877 after the hero of Greek mythology. There are three other valid species.

Discovery
The first (and incomplete) specimen of Apatosaurus was discovered in 1877 by Othniel Charles Marsh. Two years later, he found another sauropod dinosaur, which because of its tremendous size, he described as a separate genus, Brontosaurus excelus ("thunder lizard"). It was the largest dinosaur to be discovered at the time, and when its skeleton was mounted in public it immediately became one of the most famous dinosaurs.

However, in 1903, Elmer Riggs rexamined the skeleton, and found that the mounted specimen was in fact a composite of several different types of sauropod, including a very bulky skull unlike that of similar species. Based on the original remains that were left, Riggs concluded that Brontosaurus should in fact be classified as an Apatosaurus, thus rendering the former as an invalid synonym due to the taxonomic rules of priority. Changes were quickly made to the skeletons of "Brontosaurus" in museums, and the vast majority of paleontologists support Riggs's classification, with few exceptions.

Paleobiology
Apatosaurus has been well-studied, largely due to its association with "Brontosaurus". It was also one of the more common sauropods in its ecosystem.

Posture
Apatosaurus and its relatives have long been depicted with swan-like necks. Recent research and computer models suggests that they could not hold their necks far above a horizontal position, but other studies show that all living types of tetrapod naturally hold their necks up at the maximum possible vertical extension. Based upon this, it has been suggested Apatosaurus held its neck in an upward position, but with its head angled in a resting posture.

Footprints of juvenile Apatosaurus were discovered in 2006 that showed only the hind feet left tracks. This suggests that young individuals were able to run on their back legs for a short time, rather like some types of modern-day lizard.

Physiology
Based on the comparison of tidal volumes of animals, Apatosaurus is believed to have had an avian respiratory system, or something similar.

Microscopic bone study of Apatosaurus has shown that they grew very rapidly, reaching sexual maturity in approximately 10 years or so.

Tail
In 1997, a computer scientist from Microsoft published a report on the mechanics of Apatosaurus tails. Using computer models, he was able to suggest that the dinosaur's whip-like tail may actually have been able to produce sounds louder than a cannon when whipped.

In popular culture
Main article: Apatosaurus in popular culture

Even though the name "Brontosaurus" had been rendered invalid only a couple decades after its discovery, the name continued to persist in the public imagination, which made Apatosaurus one of the most famous dinosaurs in existence. One of its earliest appearances in culture was in the silent animated film, Gertie the Dinosaur, in which the title character was based off a skeletal mount in the American Museum of Natural History in New York.

A green Apatosaurus has also been the logo and mascot of Sinclair Oil for many years.