Tuesday, January 1, 2008

Dinosaurs Attack!

Dinosaurs came in all shapes and sizes, from the tiny microraptor, smaller than a modern chicken, to the massive titanosaurids which could grow as large as 60 bull elephants. Many types resembled modern lizards, while others had feathers and looked more like birds.
I often find the most popular dinosaurs are the largest and most dangerous. The mighty Tyrannosaurus Rex has inhabited the nightmares of small boys since dinosaurs were first discovered. Today I'm posting on three of the most vicious and frightening predators. If you ever meet one of these guys in the woods, run for your life.

This is one of the earliest known, large meat-eating dinosaurs. It gets its name, meaning "two-crested reptile" from the unusual crests which run along the top of its skull. This animal was featured in the movie Jurassic Park, shown spitting venom to kill its prey, although there is no evidence that dilophosaurus actually behaved this way.
It may have been a group hunter, but it has many features which suggest it was capable of bringing down prey on its own. Long, powerful hind limbs suggest it was a fast runner. The hands and toes are tipped with razor-sharp claws, and its first finger functioned like a thumb, giving it the ability to grasp and hold its unfortunate prey. The jaws are lined with blade-like teeth.
Skeletons have been found across North America and China, suggesting that it was quite widespread.

As the continents continued to drift apart during the Jurassic period, South America became separated from the other land masses. This isolation caused distinctive South American dinosaurs, including the terrifying Carnotaurus.
It had very short arms, similar to Tyrannosaurus Rex; and bony horns over the eyes. Carnotaurus might have had binocular vision, in which the field of vision for the left and right eyes overlap, allowing the animal to estimate distances accurately. The weak arms and outstanding vision suggests that it did not often attack large animals. It probably ate smaller, more agile creatures which it caught using its specialist vision and bursts of high-speed running. 

Scientists know more about the appearance and lifestyle of Allosaurus than any other large meat-eating dinosaur. In fact, hundreds of bones were found in one site in Utah. Many complete skeletons, and dozens of skulls are now known. Although it generally lived in the American southwest, some have been found as far away as Portugal and Tanzania.
Allosaurus dominated the late Jurassic. It killed using its muscular limbs and sharp claws, but it was fairly slow-moving, and must have used stealth to sneak up on its prey. A full-grown male was up to 45 feet in length, and weighed over 6 tons.

If you're interested in my previous posts on dinosaurs, click here.

There are lots of great books for the dinosaur enthusiast. Two of my favorites are National Geographic Dinosaurs, by Paul Barrett and The Illustrated Encyclopedia of Dinosaurs, by Dougal Dixon.

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