Stegosaurus
is a genus of stegosaurid armoured dinosaur from the Late
Jurassic period (Kimmeridgian to Early Tithonian) in what
is now western North America. In 2006, a specimen of Stegosaurus
was announced from Portugal, suggesting that they were present
in Europe as well. Due to its distinctive tail spikes and
plates, Stegosaurus is one of the most recognisable dinosaurs,
along with Tyrannosaurus, Triceratops, and Diplodocus. The
name Stegosaurus means "roof-lizard" and is derived
from the Greek στέγος-, stegos- ("roof") and σαῦρος,
-sauros ("lizard"). At least three species have
been identified in the upper Morrison Formation and are
known from the remains of about 80 individuals. They lived
some 155 to 145 million years ago, in an environment and
time dominated by the giant sauropods Diplodocus, Camarasaurus,
and Apatosaurus.