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Armour-clad giants of the Mesozoic Era

Posted in Animals, Historical articles, History, Nature, Prehistory on Thursday, 28 February 2013

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This edited article about the Mesozoic Era originally appeared in Look and Learn issue number 165 published on 13 March 1965.

Cretaceous Period, picture, image, illustration

Dinosaurs of the Cretaceous Period

As the world moved slowly on through millions of years we come to what is called the Jurassic Period. It is so called because many of the rocks of the Jura Mountains in Switzerland were being formed at that time. It began about 180 million years ago and lasted for some 45 million years.

The reptiles of the Triassic Period were still the lords of the earth, but many of them had developed into much larger creatures than their earlier dinosaur ancestors. Animals were developing rapidly both in varieties and numbers, so that the struggle for existence had become fiercer.

Many of the reptiles were meat eaters and hunted and ate their weaker relatives. As a result, some of the vegetable eating dinosaurs developed thick skins of armour to protect themselves against their bloodthirsty hunters.

The fiercest and most relentless hunting dinosaur of the Jurassic Period was the ceratosaurus. This savage creature grew to a length of 24 feet and was not unlike a giant kangaroo with its long hind legs and short forelimbs.

Its enormous jaws were armed with terrible curved teeth ideal for tearing the flesh of its prey.

Like most flesh-eating dinosaurs, the ceratosaurus always moved on its hind legs in a succession of bouncing leaps. Then in one tremendous leap it hurled itself on its victim – usually considerably larger than itself.

But there was one vegetarian and generally inoffensive dinosaur which even the ceratosaurus seldom attacked. This was the stegosaurus, whose tough thick skin the sharpest of teeth could not penetrate.

The ceratosaurus probably found that it was dangerous even to approach one of these living fortresses. A single blow from its powerful tail was enough to kill, and unless the attacker jumped back, sharp spines nearly two feet long tore into the victim’s soft abdomen and inflicted fatal wounds.

It was during the Jurassic Period that the first feathered bird appeared. This was the archaeopteryx, which was not much bigger than a pigeon.

The archaeopteryx was not a very good flier and moved in parachute-like jumps from tree to tree. It had strong claws on the tips of its wings, and the presence of teeth and shape of its skull showed its close relationships to reptiles.

After the Jurassic Period came the Cretaceous Period which began 135 million years ago and lasted for 65 million years. Cretaceous comes from the Latin word creta meaning chalk, and gives this period in world history its name because many of the chalk cliffs now in the world were being formed.

The Cretaceous Period saw the full development of the tyrannosaurus, the most powerful and terrifying land animal of all time. It was 50 feet long and stood 17 feet high on its huge hind legs.

Like the ceratosaurus, the tyrannosaurus was a flesh eater and levied enormous toll of its vegetarian and slower-moving relatives. Nothing could survive a bite of its tremendous jaws with their big sharp teeth.

Another creature of the Cretaceous Period was the triceratops. This rhinoceros-like reptile was about 20 feet long and eight feet high. It had a very thick skin and a frill of bone just behind the skull.

Triceratops roamed in great herds in the vast swamps of their day. They were peaceful plant-eaters, but might have charged like a tank when attacked by a flesh-eating dinosaur, and their three large and powerful horns could make them dangerous prey for even the tyrannosaurus.

Another huge creature of the Cretaceous Period was the flying pteranodon. It had a wing span of 26 feet and flew in long glides like an albatross.

The pteranodon did not have feathers, its comparatively small body being covered with a scaly skin. Unlike the ancestors of today’s birds, it did not have teeth either, but had developed a long beak which was used to snap up fish as it glided over the surface of the sea.

The Triassic, Jurassic and Cretaceous Periods together make up what is called the Mesozoic Era. Mesozoic comes from a Greek word mesos, meaning “middle,” and is given to the era which is the middle or second of the three divisions into which the evolution of animal life is divided.

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