Friday, September 17, 2010

top 3 carnivourous dinosour part1


Tyrannousaurus Rex

tyrannosaurus rex
Tyrannosaurus Rex (Greek for "tyrant lizard king"); pronounced tih-RAN-oh-SORE-us REX


Forests and swamps of North America

Historical Period:

Late Cretaceous (70-65 million years ago)

Size and Weight:

About 40 feet long and 7 tons


Other dinosaurs

Distinguishing Characteristics:

Large head with numerous teeth; stubby, almost vestigial arms

About Tyrannosaurus Rex:

Tyrannosaurus Rex is by far the most popular of all dinosaurs, spawning a huge number of books, movies, TV shows and video games. What's truly amazing, though, is how much about this carnivore that was once assumed as fact has lately been called into question. (See more facts, figures and news about Tyrannosaurus Rex, as well as a gallery of Tyrannosaurus Rex pictures and 10 Facts About T. Rex.)

For example, one controversy that's currently making the rounds among paleontologists is whether T. Rex was a hunter or scavenger. Some experts think T. Rex feasted on already dead prey, on the premise that it couldn't have been fast enough or smart enough to hunt down other dinosaurs--but it was equipped with features (such as a superior sense of smell) that are found in modern scavengers, like vultures. In another development, it's now believed that T. Rex individuals may have succumbed to trichomonosis, a parasitic disease that affects modern birds, and it's entirely possible that T. Rex juveniles were covered in downy coats of feathers, at least to judge by another genus of tyrannosaur, the Asian Dilong.

Despite how it's depicted in action movies, we don't know for sure how speedy Tyrannosaurus Rex was. Unlike the juggernaut of the Jurassic Park movies, it's possible that this dinosaur lumbered along at a poky 10 miles per hour, max--meaning a hungry female would have found it hard to outrun a kid on a bicycle! (For the record, other theropods of the late Cretaceous period, notably the ornithomimids, were capable of sprinting at a zippy 50 miles per hour or so.)



Spinosaurus (Greek for "spine lizard"); pronounced SPINE-oh-SORE-us


Swamps of North Africa

Historical Period:

Middle Cretaceous (95 million years ago)

Size and Weight:

About 50 feet long and 7 tons


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.





Deinonychus (Greek for "terrible claw"); pronounced die-NAH-nih-cuss


Forests of North America

Historical Period:

Middle Cretaceous (100 million years ago)

Size and Weight:

About 12 feet long and 150 pounds



Distinguishing Characteristics:

Light, sleek build; giant claws on hind feet

About Deinonychus:

If Deinonychus looks familiar, that's because it was popularized in the blockbuster movie Jurassic Park under the catchier name Velociraptor (real Velociraptors were actually much smaller than the fast, sleek predators depicted in Steven Spielberg's movie). See a gallery of Deinonychus pictures

Although it was far from the biggest dinosaur of the Cretaceous period, Deinonychus was especially fearsome because of its speed, its presumed ability to hunt in packs (tangled Deinonychus bones have been found in close proximity to the remains of Tenontosaurus, a tasty ornithopod), and the enormous, sickle-shaped claws on its hind feet that it used to rip apart larger dinosaurs. We can thank the famous paleontologist John H. Ostrom, who discovered the first specimen, for much of what we currently know about Deinonychus--as well as for the idea that raptors like Deinonychus eventually evolved into modern birds.

As with other raptors, the actual appearance of Deinonychus is a matter of debate: today, it's often depicted as sporting primitive feathers, though its skin may well have been more reptilian in appearance (as it was portrayed in Jurassic Park).

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