One of the most easily recognized
dinosaurs of the Late Jurassic Period, the genus
name Stegosaurus comes from Greek words
meaning "roof lizard," referring to the
belief by 19th-century paleontologists that its
distinguishing plates lay flat along its back
like shingles on a roof.
The flat triangular plates which give the Stegosaurus
its name extended from its neck to its tail,
which at the tip was armed with two to four pairs
of pointed spikes up to 4 feet long. The plates
were up to 3 feet tall (with the tallest being on
the hips), several inches thick at the base where
they attached to the body, and thin and narrow at
the tips. Covered with skin that had many blood
vessels in it, paleontologists believe that the
plates helped the animal dissipate heat. It is
also likely that the plates provided some
protection against predators, and they may also
have played a role in courtship rituals.
The front legs of Stegosaurus were
only half as long as the heavy rear legs, but
they were stout and well suited for carrying the
weight of the front of the body. The feet were
short and stubby, with four blunt toes on the
front feet and three toes on the rear feet. The
difference in size between the front legs and
rear legs suggests that the ancestors of Stegosaurus
walked on its hind legs.
The largest member of the armored dinosaur
family, Stegosaurus was up to 30 feet
long, 10 feet tall at the hips, and weighed up to
6,800 pounds. Its relatively tiny head
"housed" a brain no larger than that of
a modern dog.
Dentition and skull structure show that Stegosaurus
was an herbivore, and its "stooped"
posture suggests that it was limited to eating plants no more than 3 feet tall. Its
diet probably included ferns, mosses,
cycads, fruits, conifers, and horsetails.
The first Stegosaurus
fossil was found in Colorado in 1876 by M. P.
Felch, and was named by Othniel C. Marsh in 1877.
The most complete Stegosaurus yet found
(nicknamed Spike) was discovered near Canon City,
Colorado, in 1992 by Bryan Small, Tim Seeber, and
Kenneth Carpenter, and it was this find that
proved that Stegosaurus's plates
actually stood up along its back rather than lay
flat. Fossils from about 80 individuals
were discovered in the Morrison Formation, which
is centered in Wyoming and Colorado but reaches
into Montana, North Dakota, South Dakota,
Nebraska, Kansas, the panhandles of Oklahoma and
Texas, New Mexico, Arizona, Utah, and Idaho. Most
of the fossils discovered to date have been
adults, but a juvenile specimen was discovered in
1994 in Wyoming. Although no true Stegosaurus
fossils have been found outside of western North
America, close relatives have been found in
Western Europe, southern India, China, and
. Stegosaurus is the state
fossil of Colorado, in tribute to the number
of dinosaur skeletons found in the state.
Science Kids http://www.sciencekids.co.nz/sciencefacts/dinosaurs/stegosaurus.html
Zoom Dinosaurs http://www.enchantedlearning.com/subjects/dinosaurs/dinos/Stegosaurus.shtml
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