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Today I’m sharing a little more about dinosaurs,
such as the word dinosaur means “terrible lizard.” It comes from two
ancient Greek words: deinos, meaning “terrible” or “fearfully great,”
and sauros, meaning “lizard.” The name was created in 1842 by the
British scientist Sir Richard Owen to describe a group of large, extinct
reptiles whose fossils had been discovered. Although the name includes the word
“lizard,” dinosaurs were a distinct group of reptiles rather than ordinary
lizards.
One of the earliest known dinosaurs was Eoraptor. It
lived about 230 million years ago during the Late Triassic Period in what is
now Argentina. Eoraptor was a small dinosaur that walked on two legs and was
about the size of a large dog. Its name means “dawn thief.”
Dinosaurs were traditionally divided into two main
classifications based on the shape of their hip bones:
Saurischia — “lizard-hipped” dinosaurs, including Tyrannosaurus
rex, long-necked sauropods, and birds.
Ornithischia — “bird-hipped” dinosaurs, including Triceratops,
Stegosaurus, and duck-billed dinosaurs.
Each classification contained many smaller groups
and thousands of species. Interestingly, birds evolved from the lizard-hipped
group, not the bird-hipped group.
Scientists know of more than 1,000 species of
non-bird dinosaurs from fossils. The exact number keeps changing because about
50 new dinosaurs are named each year, while scientists sometimes decide that
two named fossils belonged to the same species. Many more dinosaur species
probably remain undiscovered.
