Dino Facts

WHAT IS A DINOSAUR?

Dinosaurs are the most recognizable and talked-about group of extinct animals ever to walk the Earth. Dinosaur means "terrible lizard", which seemed like a good name at the time. Since then, it has been found that dinosaurs aren't lizards at all - not true reptiles. And many dinosaurs were not "terrible" - most spent their lives eating plants and shying away from trouble. But it is the "terrible" dinosaurs that conjure up images of carnage - huge havoc-wrecking beasts shredding their prey with large teeth and claws. It is these images that have both frightened and inspired generations of dinosaur lovers worldwide.


CLASSIFICATION

When dinosaurs first appeared in the fossil record, they were easily separated into two distinct lineages by the orientation of their hip bones. The "lizard-hipped" (saurischian) line of dinosaurs included the herbiverous sauropods and carniverous therapods. The "bird-hipped"' (ornithischian) dinosaurs include such well-known dinosaurs as Stegosaurus, Triceratops, Edmontosaurus, and Maiasaura. It is not yet clear how these ornithischians are related to the saurischians. Sauropods were herbiverous (plant-eating) saurischians that walked on all fours. They had long necks with small heads and long, thick tails. Examples of this group of dinosaurs include Rebbachisaurus, Diplodocus, Brachiosaurus, and Saltasaurus. The lizard-hipped therapods are the most diverse group of dinosaurs. Some were among the smallest known dinosaurs, while others were the largest meat-eaters to have ever lived. They walked only on their hind legs, using their small forelimbs mainly to hold prey. Some were toothless, while others had huge, saber-like teeth. One of the key features of saurischian therapods is that they all had clawed feet. Examples of this group include Allosaurus, Dromaeosaurus, Carcharodontosaurus, Spinosaurus, Gorgosaurus, and Tyrannosaurus.


TYPES OF DINOSAURS

Tyrannosaurus rex is easily the most popular dinosaur of all. This dinosaur grew to over 40 feet long. Although it may not have been the largest, it was one of the most powerful carnivorous animals that ever lived. Tyrannosaurus had many cutting teeth up to six inches long, and appears to have had keen senses. Although some people think that Tyrannosaurus was a sluggish scavenger, most scientists believe that this dinosaur was an active predator, with powerful hind limbs built for running and equipped with large, sharp claws. Actual fossils of Tyrannosaurus rex are among the most collectible dinosaur fossils in the world.

Allosaurus was the most common carnivore in the western United States during the Late Jurassic and grew to about 40 feet long. This dinosaur had powerful hind legs that enabled it to run with speed, and smaller forelimbs, each armed with three sharp claws. The skull of this dinosaur contained more than seventy teeth that were about three inches long.

Carcharodontosaurus was a Cretaceous therapod which grew to about 27 feet long. This dinosaur had large, dagger-shaped teeth with sharp cutting edges. The forelimbs were quite short, but armed with large claws. Carcharodontosaurus remains are usually found in parts of Northern Africa.

Spinosaurus may have been the largest meat-eating animal ever to have walked the Earth, measuring well over 40 feet long. This dinosaur had very long spines on its thoracic vertebrae which may have supported a sail-like membrane. This large membrane could have served as a heat-regulating device. Spinosaurs had a mouth full of large, cone-shaped teeth, and was thought to prey more on fish than other dinosaurs.

Stegosaurus had short front legs and a narrow snout. The most distinguishable characteristic of this dinosaur was a double row of thin, vertically oriented, triangular plates along its back. These plates may have helped to control body temperature. At the end of its tail were four tall spines, arranged in pairs and angled towards the rear.

Triceratops was a bulky plant-eating dinosaur. The distinguishing characteristic of this dinosaur is the presence of three long horns on the skull. The teeth were elongated blades which were not able to crush or grind food. Triceratops probably ate fibrous plants, such as cycad or palm fronds.

Edmontosaurus is the classic duckbilled dinosaur. They were herbivores and grew to about forty feet in length. Each animal had hundreds of strong teeth that were connected by bony tissue. These tooth batteries formed long grinding surfaces for crushing plants. They had thin, leathery skin which was studded with horny bumps or tubercles.

Maisaura was one of the flat-headed hadrosaurs that grew to about thirty feet in length. They had a long, wide face with a short, wide bill. Evidence has shown that Maisaura may have had a "motherly" instinct and nested in colonies.

Rebbachisaurus was a huge, herbiverous dinosaur which grew to about 68 feet long. This dinosaur had a long, tapering head and a whip-like tail. The mouth contained many peg-like teeth, and the robust hind legs possessed large claws.

Diplodocus was one of the largest of all dinosaurs growing to 88 feet in length and weighing almost 12 tons. The neck and tail were extremely long and the limbs were quite slender. It had an elongated snout with nostrils on top of the head and weak, peg-like teeth only at the front of the mouth.

Saltasaurus was a plant-eating dinosaur that grew to about 40 feet in length. It is the first sauropod known to have had armor. The long, needle-like teeth were well suited for nipping plants.


FACTOIDS

The "Age Of Dinosaurs" makes up the majority of the Mesozoic Era. The Mesozoic extended from 248 to 65 million years ago. During this time, dinosaurs ruled the earth. Dinosaur remains have been found all over the world, on every continent, even Antarctica. They lived in swamps, forests, and even near-desert environments. Dinosaurs were probably more like today's birds and large mammals than modern-day reptiles. Some dinosaurs could probably run at great speed, either as predator or prey. Other dinosaurs lived in large, structure herds which provided some protection from meat-eating dinosaurs. Dinosaurs usually laid their eggs in nests of six or more eggs and sometimes returned to the same nesting ground year after year. Dinosaur eggs have occasionally been found in the fossil record, and complete dinosaur eggs are extremely sought-after by collectors. Sixty five million years ago, dinosaurs became extinct. Dozens of theories have been put forward as to why the dinosaurs vanished after more than 150 million years of world domination. Not even the asteroid impact theory seems to explain the whole story. The startling disappearance of the dinosaurs is probably the greatest unsolved mystery in the history of paleontology.

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