Apatosaurus ajax

Name: "deceptive lizard"
Length: 26 m
Height: 4.6 m (to hips)
Weight: 30/15 tons.
Diet: herbivore
Time: Jurassic
Location: North America

Apatosaurus was a large, long-necked quadrupedal animal with a long, whip-like tail. Its forelimbs were slightly shorter than its hindlimbs. One measurement places the total length of the species Apatosaurus louisae at 22 m (72 ft).
The skull was small in comparison with the size of the animal. The jaws were lined with spatulate teeth, which resembled chisels, suited to an herbivorous diet. Like other sauropods, the vertebrae of the neck were deeply bifurcated; that is, they carried paired spines, creating a wide and deep profile for the neck. The apparently massive neck was, however, filled with an extensive system of weight-saving air sacs. Apatosaurus, like its close relative Supersaurus, is notable for the incredibly tall spines on its vertebrae, which make up more than half the height of the individual bones. Also unusual among diplodocids is the shape of the tail, which is comparatively thin in breadth and short in height, a profile caused by the vertebral spines decreasing in height rapidly the farther they are from the hips. Apatosaurus also had very long ribs compared to most other diplodocids, giving it an unusually deep chest. The limb bones were also very robust.An article that appeared in the November 1997 issue of Discover Magazine reported research into the mechanics of Apatosaurus tails by Nathan Myhrvold, a computer scientist from Microsoft. Myhrvold carried out a computer simulation of the tail, which in diplodocids like Apatosaurus was a very long, tapering structure resembling a bullwhip. This computer modeling suggested that sauropods were capable of producing a whip-like cracking sound of over 200 decibels, comparable to the volume of a cannon firing.