Spinosaurus

Name:
Spinosaurus (Greek for "spine lizard"); pronounced SPINE-oh-SORE-us
Habitat:
Swamps of North Africa
Historical Period:
Middle Cretaceous (95 million years ago)
Size and Weight:
About 50 feet long and 7 tons
Diet:
Meat and fish
Distinguishing Characteristics:
Long, spiky protuberances from vertebrae supporting a "sail" of skin
About Spinosaurus:

If it weren't for one tell-all feature, Spinosaurus might have been indistinguishable from any other large theropod stalking the swamps of the Cretaceous period. That feature, of course, was the extensive, fin-shaped sail on its back, a thin flap of skin supported by sharp needles of bone that protruded from Spinosaurus' vertebrae. (See more facts, figures and news about Spinosaurus, 10 Facts About Spinosaurus and a gallery of Spinosaurus pictures.)

Why did Spinosaurus have this strange-looking sail? The most likely explanation is that this structure evolved for cooling purposes in the hot northern African climate in which Spinosaurus lived (a bit like the big, floppy ears of African elephants). It may also, as a byproduct, have been a sexually selected characteristic--perhaps male Spinosaurus with bigger sails had more success mating with females.

By the way, paleontologists now believe that Spinosaurus was the largest carnivore that ever lived--outclassing even Tyrannosaurus Rex by one or two tons. Fortunately--or unfortunately, if you happen to be a movie producer--these two dinosaurs didn't share the same time or territory, T. Rex living tens of millions of years later in North, rather than South, America.