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About The Animals
An Overview Of Dinosaurs

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The story of the first discovery of dinosaur fossils began in the 1820s, specifically in the year 1824, when an Englishman named William Buckland described a huge fossil jaw that had been dug up near an English town. He was sure it had come from some kind of gigantic meat-eating reptile. He called the creature Megalosaurus (mehg ul loh SAWR uhs), which means "giant lizard." It was the first dinosaur to be named.

When Gideon Mantell, an English doctor, stumbled upon some unusual teeth and bones in a quarry, the dinosaur world began to really show forth. Dr. Mantell realized there was something extremely different about these animal remains, and believed that he had discovered an entirely new group of reptiles. He wrote to his wife describing the teeth, believing that they must have come from some kind of ancient giant iguana. He therefore named the creature Iguanodon (ih GWAHN uh dahn), which means "iguana tooth." It was the second dinosaur to be named, but there still was yet no such word as dinosaur.

During the next few years, fossils of other ancient giant reptiles were found and named. There were Hylaeosaurus (hy lee uh SAWR uhs), or "forest lizard," and Cetiosaurus (see tee uh SAWR uhs), or "whale lizard," in England, and Plateosaurus (plat ee uh SAWR uhs), or "flat lizard," in Germany. Scientists now realized that a great many different kinds of giant reptiles must have existed.

A name was needed for these reptiles, just as there is a name for every other group of animals that are alike. In 1841, the English scientist Richard Owen (a creationist) suggested these huge, terrible-seeming reptiles should be called dinosaurs. The word is made up from the Greek words deinos, which means "terrible," and sauros, which means "lizard." Hence dinosaurs, or "terrible lizards," is what everyone began calling them. As it turned out, this really wasn't a good name, because dinosaurs were not lizards.

But although dinosaurs had now been discovered, scientists for some time had only a few bones or teeth of each creature. Therefore, they thought of them as simply looking much like the lizards of today, only many times bigger. In 1851, an artist made some statues showing what scientists thought dinosaurs had looked like. All the statues were fat-bodied, four-legged, lizard-like beasts with big, blunt heads.

Then, in 1858, an almost complete skeleton of a dinosaur was dug up in America. Scientists saw that this animal had not been a bit like a lizard or any other kind of reptile. They could tell that it must have walked upright on its two back legs, much like a kangaroo. They named it Hadrosaurus (had ruh SAWR uhs), meaning "bulky lizard."

As time went on, more and more whole skeletons of different kinds of dinosaurs were dug up. Today, we know of more than eight hundred different dinosaur kinds.

What Differentiates The Dinosaur

Other than the enormous size of many dinosaurs, the most prolific feature that distinguishes them from other reptiles (such as crocodiles) is the position of their limbs. Dinosaurs had posture that was fully erect, similar to that in mammals. Most other reptiles have limbs in a sprawling position. For instance, compare the way a crocodile "walks" with that of, say, a cow. Dinosaurs would have moved similar to a cow, with the limbs supporting the body from beneath. Crocodiles "waddle," as their limbs project sideways from their body.

The Dinosaur Families

Scientists have divided dinosaurs into two groups, or orders, according to the way their hipbones are formed. In one order, almost all dinosaurs have hipbones somewhat like those of other kinds of reptiles, so they are known as saurischians (saw RIHS kee uhnz), or "lizard hips." In the other order, dinosaurs have hipbones that are more like those of birds. They are known as ornithischians (awr nuh THIHS kee uhnz), or "bird hips." However, the similarity between the two stops here. To take the next step and claim that birds evolved from dinosaurs exceeds and crosses all borders of science. At that point, it becomes a simple belief. A misguided theory.

Each of the two orders is made up of a number of dinosaur families. The cat family, for example, is made up of lions, tigers, leopards and many other creatures that are all much like.


Saurischian dinosaurs, again, were characterized by a lizard-like pelvis, with a single bone projecting down and back from each side of the hips. This pelvis construction was similar to that of other ancient reptiles but, unlike other reptiles, saurischians had stronger backbones, no claws on their outer front digits, and forelimbs that were usually much shorter than the hind limbs. There were three basic kinds of saurischians: theropods, prosauropods, and sauropods.


Nearly all theropods were bipedal flesh-eaters. Some theropods, such as Tyrannosaurus, reached lengths of 12 m (39 ft) and weights of 5 metric tons. In large theropods the huge jaws and teeth were adapted to tearing prey apart. Fossil trackways reveal that these large theropods walked more swiftly than large plant-eating dinosaurs and were more direct and purposeful in their movements. Other theropods, such as Compsognathus, were small and gracefully built, resembling modern running birds such as the roadrunner. Their heads were slender and often beaked, suggesting that these theropods fed on small animals such as lizards and infant dinosaurs. Some of them possessed brains as large as those of modern chickens and opossums.

Other theropods, called raptors, bore powerful claws, like those of an eagle, on their hands and feet and used their flexible tails as balancing devices to increase their agility when turning. These animals appear to have hunted in packs.


Unlike the theropods, the prosauropods had relatively small skulls and spoon-shaped, rather than blade-shaped, teeth. Their necks were long and slender and, because they were bipedal, the prosauropods could browse easily on the foliage of bushes and trees that were well beyond the reach of other herbivores. A large clawed, hooklike thumb was probably used to grasp limbs while feeding. The feet were broad and also heavily clawed.

In the ornithischian order there are six families of two-legged plant-eating dinosaurs called ornithopods (awr NIHTH uh pahdz), or "bird feet." There are three families of ceratopsians (sehr uh TAHP see uhnz), or "horned faces," three families of ankylosaurs (an KY luh sawrz), or armored dinosaurs, and one family of stegosaurs (STEHG uh SAWRZ), or "roofed reptiles." Stegosaurs got their name because they had bony plates that looked like roof shingles sticking up out of their backs.

Each dinosaur family is called a genus. All the animals in a genus are alike, but are different from those in every other genus.


Sauropods include such dinosaurs as Apatosaurus (formely known as Brontosaurus) and Diplodocus. These dinosaurs walked on four pillarlike legs and some probably reached lengths of more than 82 feet, weighing about 90 metric tons. Their feet usually bore claws on their inner toes, although they otherwise resembled the feet of an elephant. Indeed, they may be compared to gigantic elephants, with the sauropods' long necks performing the function of an elephant's trunk, and their gizzard stones acting very similar to the teeth of an elephant. Some sauropods, like the Apatosaurus, used their long, thin tails as a whip for defense, while others used their tails as a club.


In ornithischians the bony structure that projected down and back from each side of the hips was composed by two bones, making their hips resemble that of birds. Interestingly, most dinosaurs that, in appearance, resembled a bird, possessed a lizard hip, whereas the large dinosaurs, such as the Stegosaurus, possessed a bird hip. An interesting fact indeed, posing many questions to evolutionists. What bird of our day is the evolutionary descendant of the gigantic Ankylosaur, Stegosaurus, Trachadon (30 feet long, 18 feet wide), Iguanodon, or Parasaurolophus?

There are five kinds of ornithischians: stegosaurs, ankylosaurs, ornithopods, pachycephalosaurs, and ceratopsians.


Stegosaurs were plated dinosaurs, such as the most popular Stegosaurus, who bore a double row of triangular bony plates along its back. In these narrow plates contained tunnels through which blood vessels passed, allowing these animals to radiate excess body heat or to warm themselves in the sun. In a way, stegosaurs resembled gigantic porcupines, and they defended themselves by turning their spined tails toward their enemies.


Ankylosaurs were similar in size to stegosaurs but otherwise resembled giant horned toads. Interestingly, a few even possessed a bony plate in each eyelid as well as large tail clubs. Indicating that their necks needed protection from the attacks of carnivorous dinosaurs, they were protected by thick, heavy bony rings and spines.


Ornithopods ranged in size from small runners about 6 feet long and weighing 33 pounds, like Hypsilophodon, to elephantine cows about 32 feet long and weighing over 4 metric tons, like Edmontosaurus. Ornithopods possessed flexible jaws and grinding teeth. They have earned the name duck-billed dinosaur due to their broad beaks, and their noses supported cartilaginous sacks or bony tubes, indicating that these dinosaurs may have communicated by trumpeting. In a well-known Encyclopedia, the following statement is interestingly made:

"Fossil evidence from the late Cretaceous Period includes extensive accumulations of bones from ornithopods drowned in floods, indicating that duck-billed dinosaurs often migrated in herds of thousands."

Although in error regarding the "Cretaceous Period," they hit the nail on the head with their belief of sudden death from a flood. Indeed, that is how many dinosaurs met their fate.


Being bipedal (two-footed) dinosaurs, pachycephalosaurs possessed thick skulls, flattened bodies, and tails surrounded by various bony rods. The Pachycephalosaurus, a very large animal more than 15 feet long, had a skull that was capped by a rounded dome of solid bone. It is likely that the males possessed the thickest domes for butting heads during mating contests and herd dominance. Today eroded pachycephalosaur domes are often found in stream deposits.


The 4-footed ceratopsians, or horned dinosaurs, possessed a saddle-shaped bony frill that extended from the skull over the neck, and typically bore horns over the nose and eyes. The most popular and well-known, the Triceratops, could reach lengths of over 26 feet and often weighed over 12 metric tons. Serving two purposes, their frill protected the vulnerable neck, and, containing a network of blood vessels on its undersurface, it was used to radiate excess heat. It is widely believed that ceratopsians lived in herds, due to the large accumulations of fossil bones found together.

How Dinosaurs Get Their Names

Pachycephalosaurus. Dromiceiomimus. Compsognathus. Indeed, many dinosaur names are strange and difficult to pronounce. Why is that?

A person who discovers a new kind of dinosaur is entitled to name it. In most cases, of course, that person is a scientist. Scientists all over the world years ago agreed that any kind of newly discovered animal, whether living or extinct, must be given a scientific name. The name is usually made up from words taken from Greek or Latin, languages with which most scientists are familiar. Thus a newly discovered dinosaur gets a name that scientists can understand, regardless of what language they speak.

The name usually tells something about the dinosaur. For example, when one scientist discovered a dinosaur that had a large, curved, sharp claw on each hind foot, he named it Deinonychus (dy noh NIHK uhs), or "terrible claw." Or, the name may simply tell where the fossil was found. A dinosaur whose skeleton was found in Shantung, China, was name Shantungosaurus (shan tuhng uh SAWR uhs), or "Shantung lizard."

Every dinosaur gets two names - a genus name and a species name. A genus name tells what kind of dinosaur it is, such as a Triceratops (try SEHR uh tahps), or "three-horned face." But there are often several kinds of just slightly different creatures in any genus group, and these are called species. So, each species gets a name that identifies it. Thus, the biggest kind of Triceratops is named Triceratops horridus, or "dreadful three-horned face," while another species is named Triceratops eurycephalus (yur ee SEHF uh luhs), or "broad-headed three-horned face."

A person who discovers a new species of dinosaur can also use someone's last name as the dinosaur's species name. The scientists who gave Iguanodon its species name, called it Iguanodon mantelli, meaning "Mantell's iguana-tooth." He gave it this species name to honor Gideon and Mary Ann Mantell, who found the first Iguanodon fossils. Last names have also been used as genus names for dinosaurs. One dinosaur is called Lambeosaurus (lam bee uh SAWR uhs), or "Lambe's lizard," after Lawrence Lambe, who helped discover several kinds of dinosaurs.

Dinosaur names can get changed, and many have. This usually happens when a person finds what they think is a new dinosaur and gives it a new name. Later, it turns out to be a known dinosaur. When Hylaeosaurus was named, scientists weren't sure what kind of dinosaur it was. Some years later, an armored dinosaur was found and named Polacanthus (pahl uh KAN thuhs), or "many thorns." But, long afterwards, more Hylaeosaurus fossils were found, and it turned out that Hylaeosaurus and Polacanthus was dropped. The older name, Hylaeosaurus, is now the official name for that kind of dinosaur.

Although much more could be written on the subject, this is a general overview of dinosaurs as we know them.


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