2012-03-31 02:00:45
Stegosaurs are among the best known and most recognizable dinosaurs. They are medium-sized herbivores that lived primarily in the Northern Hemisphere from the Middle Jurassic to the Lower Cretaceous, between 176 and 100 million years ago. Its most striking characteristic is the double row of plates or bony spines that runs along its back, from the neck to the tail.
Stegosaurs are among the first known dinosaurs, and their appearance, or rather the image we have of these dinosaurs, has changed a lot since their discovery. The species that gives the group its name, Stegosaurus armatus, was described by the American paleontologist Othniel Charles Marsh in 1877 from fossil remains found in Colorado. At first, Marsh thought it was a turtle-like aquatic reptile, its body covered in overlapping plates like shingles on a roof. Hence the animal’s scientific name, Stegosaurus, which means “roofed lizard.” Later, with the discovery of more specimens, it became clear that the plates did not form a shell, but were aligned vertically on the animal’s spine. This is how the traditional image of these dinosaurs appeared, with their heads at ground level, their backs arched in the shape of a semicircle, their legs bent to the sides, like in lizards, and dragging their tails. But the most recent studies indicate that stegosaur legs supported the body like columns, and the head and tail stood taller than previously thought.
The stegosaurus also contributed greatly to the ancient idea that dinosaurs were slow, clumsy, and stupid animals. Its brain was one of the smallest among dinosaurs, no bigger than a dog’s, which is minuscule for an animal weighing several tons. In addition, a second brain was attributed to it, located on the hip, which was in charge of controlling the hind legs and tail. Stegosaurs, like other dinosaurs, have a thickening at hip level in the canal that houses the spinal cord; a thickening up to twenty times larger than his own brain. But it is currently thought that this hole did not house a second brain, but rather a glycogenic body, a structure that is also present in birds, whose function is not clear, although it is supposed to supply energy in the form of glycogen to the nervous system. .
About two dozen stegosaurus species are currently known, although some of them have only found very fragmentary remains. Stegosaurus fossils have been found in the United States, China, England, France, Spain, Portugal, Tanzania, and South Africa. Eggs have also been discovered in Portugal, footprints in the United States, and skin impressions in China.
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