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         A Molecule Is Born
4 Billion BC

EARTH 
	All life forms are made mostly of a few common atoms such as hydrogen, oxygen, nitrogen and carbon. These atoms stick together in groups called molecules. Atoms are like the letters of the alphabet; molecules are like words formed from those letters. A few letters can make an endless variety of words. 
	Many scientists think that after the earth formed the atmosphere consisted mainly of hydrogen, ammonia, and methane. 
	These, dissolved in the ocean, were the basic ingredients of life. The chemicals mixed in the water, forming a soup of more complicated molecules. Sunlight provided the energy to cook the soup. Lightning accelerated the process, helping more complex chains of carbon atoms to form. 
	By recreating what they believe the surface of the early earth must have been like, scientists have created some of the organic compounds from which life is built, but they are still far from creating life. 
	For life to exist, carbon is very special. Most atoms can only stick to themselves in small clusters. But carbon is unusual in that its atoms can stick to each other in endless chains, like sticky marbles. 
	Perhaps when conditions were perfect some complicated molecules formed in the early seas, then broke into two identical halves. Then, when the right molecules ("food") stuck on them, they might have formed identical copies of themselves. 
	This would have been the first self-reproducing molecule, meaning that it made identical copies of itself, like a tiny photocopy machine. Each of those copies could then split in two and form more and more copies, multiplying throughout the oceans like rabbits. Perhaps this was how life began.
                                  JTyrannosaurus' Smaller Brother
70 Million BC;29 Feet;1.8 Tons

ALBERTA, CANADA 
	At 29 feet long, Albertosaurus was only about half the size of its closest cousin Tyrannosaurus. Despite the difference in size, Albertosaurus was built in much the same way as its other meat-eating relatives. It had a large muscular head, a mouth full of sharp, serrated teeth and a powerful jaw that could deliver a fatal bone-crushing bite to the neck of its victims. 
	Like Tyrannosaurus, Albertosaurus had puny forearms that were too short to reach up to its mouth to feed. With only two functional fingers on its arms, as opposed to three, grasping for food would have also been very difficult. Some believe that Albertosaurus used these tiny limbs to hold on to females during mating. Others think they were used to help the dinosaur raise itself up when it was lying prone on the ground. 
	Paleontologists still wonder whether Albertosaurus and its flesh-eating relatives were fast-moving predators. Their bodies were too heavy to chase prey at high speeds for very long distances. More likely, Albertosaurus waited for its victims, then charged them at speeds of 18 or 20 miles an hour. Once close enough, Albertosaurus could clamp its powerful jaws down on the neck of its victim and then deliver a stunning blow with its powerful clawed legs. 
	LOCALITY: Alberta, Canada; Montana, USA 
	LENGTH: 29 Feet 
	WEIGHT: 1.8 Tons 

Allosaurus: Giant Killer
150 Million BC;39 Feet;1-2 Tons
UTAH, UNITED STATES 
	Allosaurus, or "leaping reptile," was one of the most common types of dinosaurs known as "carnosaurs," or meat-eaters. It lived about 150 million years ago, roaming parts of western North America and Africa in search of prey. Though not nearly as large as its close relatives Tyrannosaurus and Albertosaurus, Allosaurus was quite a fearsome killer. An adult Allosaurus could grow up to 39 feet long, 15 feet tall and weigh between 1 - 2 tons. As you can see in this movie, Allosaurus' skull was quite big in relation to its body -- almost 2.5 feet long -- and its jaws were lined with about 70 razor-sharp, curved, saw-edged teeth, just like the blade of a steak knife. These teeth pointed backwards so that huge pieces of meat could be forced down into Allosaurus' hungry mouth. 
	Allosaurus had short but strong front claws, and four large claws on each of its back feet, three of which helped to carry its weight. These claws also enabled Allosaurus to hold down and tear at its prey. 
	Scientists disagree about the hunting habits of Allosaurus. Some believe that the dinosaur was too large and clumsy to be a very effective hunter, while others argue that Allosaurus was quite agile and hunted down plant-eating dinosaurs in small packs. In fact, in North America, bones of Apatosaurus have been found with teeth marks that match those of Allosaurus! 
	LOCALITY: USA; Tanzania 
	LENGTH: 39 Feet 
	WEIGHT: 1-2 Tons
CSelf-Sufficient Eggs
400 Million BC

ON DRY LAND 
	Before reptiles could spend all their time on dry land they had to develop a new way to give birth to their young. No matter how much time amphibians spent living on dry land, they always had to return to the water in order to lay their eggs. That's because baby amphibians, known as larvae, were too small and frail to survive on land without being crushed or drying out. 
	So about 400 million years ago, certain amphibians apparently began to lay a new kind of egg. It was called the "amniotic" egg. An amniotic egg is a specialized egg which is very similar to the eggs birds and lizards lay today. The first amniotic egg was covered by a leathery shell (not a hard shell like a chicken egg), and contained everything needed for a young, undeveloped animal called an embryo, to grow into a fully functioning baby that would eventually crack through the shell. 
	Inside, the amniotic egg was divided into four major cavities which performed special functions to help the embryo develop. The main cavity held the embryo, which was surrounded by a fluid called the amnion that helped keep the embryo moist and cushion it from the vibrations of the outside world. Another cavity called the yolk, contained a food supply for the embryo. The waste products from the growing embryo went into another cavity called the alantoic cavity. Finally, oxygen entered through tiny holes in the shell into an area known as the chorion. 
	With sturdy, self-sufficient eggs like these, reptiles were free to move as far they liked on land, inhabiting new terrain like grassy lands and dry, hot deserts.
LAnkylosaurus: The Armored Tank
70 Million BC; 33 Feet;4 Tons

ALBERTA, CANADA 
	Ankylosaurus was indeed the armored tank of the dinosaurs. Massively built, this creature weighed close to four tons and measured 33 feet long, making it the largest of the group of armored dinosaurs known as ankylosaurs. 
	Few predators could pierce its tough defenses. Ankylosaurus was covered from the top of its solid skull to the tip of its powerful tail with bands of bony armor-plating and tall hard spines. Even its eyelids were armored. Ankylosaurus had a broad body measuring 16 feet across. Its skull alone was up to 2-1/2 feet long with sturdy triangular horns at the corners of its head. One of the most interesting characteristics of Ankylosaurus was the heavy bony club at the end of its tail. Made of fused bone embedded in leathery hide, this acted as a lethal weapon against most ferocious predators. 
	Ankylosaurus was among the last dinosaurs to survive the Cretaceous Period and lived primarily in North America. They were plant eaters and may have lived together in small groups. 
	LOCALITY: Alberta, Canada; Montana, USA 
	LENGTH: 33 Feet 
	WEIGHT: 4 Tons 

OThe Long Necked Dinosaur
145 Million BC;70 Feet;33 Tons
UTAH, UNITED STATES 
	As you can see in this movie, Apatosaurus -- also known as Brontosaurus -- had a very long neck. It took advantage of its neck to reach the leaves and branches on the tops of trees, using its massive tail for support while standing on its rear legs. It had to eat tons of plants and leaves every day just to maintain its incredible body weight. 
	These were not slow, defenseless creatures, either. In a battle with its enemy Allosaurus, Apatosaurus could have reared up on its hind legs and then brought its entire body down on its predator. Apatosaurus' long tail was also not a bad whip. 
	Recently, Dinamation International Society has discovered what may be the largest Apatosaurus skeleton ever found. It may have measured up to 95 feet long!  LOCALITY: Oklahoma, Utah, Wyoming, USA 
	LENGTH: 70 Feet 
	WEIGHT: 33 Tons
Apatosaurus: Thunder Lizard
145 Million BC;70 Feet;33 Tons

UTAH, UNITED STATES 
	First, there is the crashing sound of plants and trees being trampled. Then, the terrible shaking of the earth. In the distance, an immense shape the size of a small building appears. Apatosaurus used to be called "Brontosaurus," which meant "thunder lizard" and referred to the loud noise this enormous dinosaur must have made as its 33-ton body lumbered across the plains of North America. Scientists no longer use the name Brontosaurus because the first fossils to be discovered of this creature were actually given the name Apatosaurus. 
	Apatosaurus was indeed one of the largest animals ever to walk the earth. It belonged to the group of plant-eating Sauropods that included Diplodocus and Camarasaurus. Like these other dinosaurs, Apatosaurus had a very long neck and an even longer tail. An adult Apatosaurus measured up to 70 feet in length and had a tiny head in comparison to its body: only 22 inches long! Although not as long as its close relative Diplodocus, Apatosaurus weighed nearly three times as much, primarily because its bones were denser and its heavy tail was made up of almost 82 interlocking vertebrae. 
	LOCALITY: Oklahoma, Utah, Wyoming, USA 
	LENGTH: 70 Feet 
	WEIGHT: 33 Tons
HArchaeopteryx: The Birdosaurus
140 Million BC;14 Inches;Unknown

SOLNHOFEN, GERMANY 
	Is it a dinosaur? A bird? Or both? In 1861, when German stone cutters discovered the nearly perfect fossil imprint of Archaeopteryx in a block of 140-million-year-old limestone in a stone quarry, they didn't know what to make of it. At first, scientists thought the fossil was the imprint of a tiny meat-eating dinosaur. Then they realized that the faint outlines surrounding the skeleton were actually imprints of feathers. 
	As it turned out, the discovery of Archaeopteryx was one of the most important dinosaur finds ever. It proved what many scientists had long believed. There was a strong link between the dinosaurs of long ago and the birds we know today. 
	Indeed, Archaeopteryx was something of a cross between a dinosaur and a modern bird. About the same size as a pigeon, it had a small head, large eyes and feathers which covered most of its body. But like dinosaurs, Archaeopteryx had teeth in its jaw, claws on its fingers and a long bony tail. Also, the bones throughout its body were much heavier than a bird's and it didn't have as many muscles with which to flap its wings. Instead of flying, Archaeopteryx probably used its wings to fly short distances or glide from tree to tree catching insects or occasionally attacking small animals on the ground. 
	LOCALITY: Germany 
	LENGTH: 14 Inches 
	WEIGHT: Unknown
A Singular Big Bang
15 Billion BC

UNIVERSE 
	Most scientists believe the universe began from a "singularity," an impossible-to-imagine point so small that it had no size at all. Then that point, which they think contained everything that there is in the universe -- matter, energy, and even time and space -- exploded with an enormous rush. 
	Scientists don't know what caused this point to explode in a "Big Bang" about 15 billion years ago, and they don't know what -- if anything -- existed before the bang occurred, or even if there was a "before" before it happened. 
	So-called "black holes" are believed to be similar to this singularity except that they contain far less of the universe. Black holes are believed to be collapsed stars of such density and gravitational strength that once caught, nothing -- not even light -- can escape their pull. 
	Scientists believe that as the Big Bang exploded outward in a blaze of energy, the universe was blown up like a child blows up a balloon.
Heavy Elements Created
15 Billion BC

UNIVERSE 
	Scientists believe that as the universe expanded following the Big Bang it cooled rapidly and some of its energy condensed into tiny particles. Then an unexplained phenomenon called electromagnetic force began pulling these tiny particles together into hydrogen atoms. 
	Gravity, another mysterious force, caused more and more atoms to gather together. The larger these clouds of atoms, the stronger the gravitational force became, until the gravity squeezed the atoms so hard that it sparked a nuclear reaction and the clouds became huge balls of fire. Stars blinked on all over the universe. 
	These stars burned at tremendously high temperatures as their hydrogen atoms joined to form helium atoms in a process called fusion. Small stars can burn like this for billions of years, until they run out of hydrogen. Then they cool down and collapse, becoming white dwarfs. But the largest stars burn up much more quickly, then collapse, fusing their atoms together into heavier elements. Finally they explode into supernovas, scattering new atoms of copper, gold, uranium and many other elements into the surrounding galaxy. 
	The earth and all its plants and animals were formed from these heavier elements.
*Dinosaurs: From Lab to Museum
1992 AD

LOS ANGELES, CALIFORNIA 
	Once a dinosaur has been removed from the ground, much work remains to be done. 
	In the laboratory the bones are unpacked from their protective coverings and cleaned. Scientists use microscopes and brushes and tiny tools, such as dental picks, to completely remove the soil surrounding the bones. They also make pictures of each of the pieces. The bone fragments are strengthened with liquid plastics and glued together. The process or recreating a dinosaur skeleton can take years. 
	After scientists discover what the dinosaurs looked like, they can make molded copies of the bones to display in museums. 
	These reproductions are often arranged in a realistic fashion to show museum visitors what the dinosaurs looked like, how they acted, and what their environment was like. 

Heavier Than Twelve Elephants!
150 Million BC;75 Feet;89 Tons

TANZANIA, AFRICA 
	It is possible that no land animal, living or dead, was as massive as the giant plant-eating dinosaur Brachiosaurus. Measuring 75 feet in length, Brachiosaurus weighed close to 89 tons: eight times that of its close relative Diplodocus and 12 times that of a modern elephant! 
	These giants lived during the late Jurassic period and their skeletal remains have been found in Africa as well as North America. 
	Brachiosaurus' neck was so long that it made up almost half of its total height. By comparison, its head -- which measured only three feet long -- was minuscule. The name Brachiosaurus means "arm reptile." It was given to the dinosaur because its front legs were much longer than its hind legs, a very unusual feature for most Sauropods. This had advantages though. When combined with its enormous neck, Brachiosaurus could raise its head close to 45 feet, or as high as a three story building. Brachiosaurus was once thought to spend most of its time underwater using the two nasal openings on the top of its head as snorkels. That theory has been rejected because the water pressure on its massive body would have made breathing almost impossible. 
	LOCALITY: Colorado, USA; Algeria, Tanzania, Africa 
	WEIGHT: 89 tons 
	LENGTH: 75 feet 

Brontosaurus: Swamp to Tree Top
145 Million BC;70 Feet;33 Tons 

COLORADO, UNITED STATES 
	Scientists used to think that Brontosaurus (now more commonly known as Apatosaurus) was exclusively a swamp dweller. 
	They thought this huge animal -- the size of six elephants -- was far to heavy to support itself outside the water. The water, they said, would help keep the 33-ton giant from collapsing of its own weight. 
	But then they uncovered clean, sharp fossilized Brontosaurus tracks. The tracks were not in mud -- the kind of surface you would expect at the bottom of a river -- but in sand. Also, right next to them were the footprints of the deadly Allosaurus, which was undoubtedly a land-dwelling dinosaur. Unless the Allosaurus had been scuba diving, this meant Brontosaurus was perfectly able to get around on land. 
	Now scientists believe Brontosaurus was a land animal that grazed on leaves and branches from the tops of trees. 
	LOCALITY: California, Oklahoma, Utah, Wyoming, USA 
	LENGTH: 70 Feet 
	WEIGHT: 33 Tons 
Did Camarasaurus Have a Trunk?
150 Million BC;60 Feet;20 Tons

UTAH, UNITED STATES  
	Camarasaurus, or "chambered reptile" roamed the moist, lush plains of North America during the late Jurassic period, feeding on the rich vegetation that covered the land. A fairly common long-necked plant eater, Camarasaurus probably traveled in herds which migrated from one feeding place to another. 
	Camarasaurus had a small head which was perched on top of an extra-long neck that enabled it to reach even the highest branches of trees in search of food. An adult Camarasaurus could grow to 59 feet in length and was very similar in build to its close relative the Brachiosaurus, only much smaller. 
	An odd trait of Camarasaurus was its nostrils, which were placed high up on its head, just in front of the eyes. Scientists once thought that Camarasaurus may have lived mostly underwater with only its head poking out, using these nostrils to breathe. But that was thought unlikely considering the weight of the water pressure. More recently, some believe that Camarasaurus may have had a long trunk, like that of an elephant, which extended down from its nostrils. Others believe that Camarasaurus used its nostrils as a cooling device for the brain. 
	LOCALITY: Colorado, Oklahoma, Utah, Wyoming, USA 
	LENGTH: 60 Feet 
	WEIGHT: 20 Tons 
The Explosion Of Life
570 Million BC

EARTH 
	About 570 million years ago nothing much seemed to be happening on the earth's surface. The upper atmosphere was finally strong enough to keep oxygen created by algae from escaping into space and volcanoes continued to erupt, but no longer with the same intensity. 
	Beneath the seas, however, a tremendous abundance of living creatures suddenly began to flourish. During this time, known as the Cambrian Period, the world's seas filled with corals, sponges and anemones. Ancient shellfish such as oysters, mussels and bivalves also began to cover the sea floor, while worms, jellyfish and primitive squids floated along the water's currents scooping up algae and other organisms for food.
The World's a Jungle 
320 Million BC

EARTH 
	In the Carboniferous Period of 360 to 286 million years ago, large swampy jungles like these spread across much of the earth. The planet's average temperature was much higher than it is today and the air was humid, making conditions perfect for plants to thrive. 
	Plants such as the giant club moss and horsetail fern grew increasingly large. They developed thicker trunks and reached heights of 70 and 80 feet. Also, the first trees, known as gymnosperms, began to appear. Gymnosperms are trees like the pine and the ginkgo, which have protected seeds. 
	At the same time, flying insects like giant dragonflies with two-foot wingspans darted among the vines and branches of the jungles. On the ground, a more interesting development was taking place. Scientists believe lobe-finned fish -- with their muscular fins and primitive lungs -- were becoming the first amphibians (animals which could spend time both in and out of the water).
The Slow Death Theory
50 Million BC

EARTH 
	One of the simplest theories of why the dinosaurs died out is that the earth's climate gradually changed. As the continents of the earth continued to shift 60 million years ago, new mountains rose and sea levels gradually dropped. As a result, the average air temperature around the earth could have fallen 17 degrees or more, changing weather patterns and giving rise to new kinds of plants. It's possible, think some scientists, that dinosaurs were not well adapted to such colder weather. If they were, indeed, cold-blooded animals, then the colder air temperature would have made them more sluggish and less able to hunt or forage for food. 
	Another possibility is that dinosaurs were not well-suited to the new vegetation, such as flowering plants and leafy trees which thrived in a cooler climate. Convincing as this theory sounds, it does not explain why dinosaurs did not simply move to the tropical regions of the world where the temperature is far warmer.
Marsh and Cope: The Fossil War
1877 AD

NEW HAVEN, CONN. 
	In the 1870s the intense rivalry between two Americans, O.C. Marsh, a professor at Yale and E.D. Cope, a brilliant scientist from Philadelphia, led to some of the greatest dinosaur discoveries of all time. 
	The rivalry began in 1866 when Cope showed Marsh his study of a dinosaur skeleton found in Kansas. Upon closer inspection, Marsh discovered a big mistake in Cope's drawing. The head of the dinosaur (or, more technically, a plesiosaur, an aquatic reptile) was placed on the wrong end of the skeleton. After Marsh published his findings, Cope was so upset that he tried to destroy every copy of the report before anyone could read it. 
	Ten years later, when fragments from a rich fossil deposit in Colorado were brought separately to each of the two men, they immediately headed out West determined to be the first to unearth the most spectacular dinosaur fossils. This period became known as the "great dinosaur rush" and led to some of the largest dinosaur discoveries in the world. 
	With money from their wealthy families, Marsh and Cope sent huge teams of explorers to Colorado, Wyoming and Montana on long arduous fossil digs. Between 1877 and the late 1890s, the two men discovered nearly 130 new species of dinosaurs, including the well-known Brachiosaurus, Triceratops and Tyrannosaurus. Today, some of the largest, most breathtaking dinosaur displays in the world are the result of this intense rivalry.
Corinthian Helmet Reptile
80 Million BC;33 Feet;5 Tons

ALBERTA, CANADA 
	Corythosaurus is certainly called the "Corinthian helmet reptile" for a good reason. With its unique head crest, Corythosaurus is one of the best known of the duckbilled dinosaurs called hadrosaurs which inhabited the dense forests of what is now Montana and Canada at the end of the dinosaur age. Measuring 33 feet in length and weighing five tons it was also one of the largest dinosaurs of its kind. 
	Of course, the most amazing feature of this massive plant-eater was the large, almost one-foot high, hollow crest on the top of its head. Shaped like a large upright dinner plate, this crest spanned from the front of the dinosaur's forehead to the back of its skull. Like other crested duck-billed dinosaurs, Corythosaurus' crest was filled with nasal passages. But it remains a mystery what these crests were used for and why some hadrosaurs had them while others did not. 
	The most popular theory held today is that the crest functioned as either a sounding device that enabled Corythosaurus to warn others of danger or as an enlarged sensory area which increased the creature's sense of smell. 
	LOCALITY: Alberta, Canada; Montana, USA 
	LENGTH: 33 Feet 
	WEIGHT: 5 Tons
Deinosuchus: Big As a Dinosaur
130 Million BC;50 Feet;Unknown

TEXAS, UNITED STATES 
	The first primitive crocodile appeared on the earth 230 million years ago, about the same time the first dinosaur appeared. Interestingly, both dinosaurs and crocodiles are from the same group of reptiles known as "archosaurs" or "ruling reptiles." But somehow, crocodiles survived while dinosaurs did not. 
	Little has changed in the crocodile since its prehistoric relatives showed up in the Mid-Triassic Period of the earth's history. Originally, many crocodiles probably spent their time on land hunting for insects or small animals. Over time, however, they became the semi-aquatic animal we know today. 
	One ancient crocodile named Deinosuchus, however, was quite unique. Only the skull of Deinosuchus has been found and it measured an unbelievable six feet six inches long. If Deinosuchus was built the same way modern crocodiles are built then its body would have been 50 feet long. With its massive jaw Deinosuchus would have been one of the most ferocious meat-eaters alive at the time. Lying hidden in the swamps, Deinosuchus could have seized even medium-sized dinosaurs with a single snap of its enormous jaws. 
	LOCALITY: Texas, USA 
	LENGTH: 50 feet 
	WEIGHT: Unknown
Charles Darwin's Revolution
1859 AD

GALAPAGOS ISLANDS 
	Charles Darwin was a little unsure. Was he ready to publish his findings? Twenty-two years earlier, in 1836, he had returned to England with the germ of a radical new idea about the origin of life. 
	On the Galapagos Islands near South America, Darwin had seen animals that were related -- but different. Perhaps, he thought, the mechanism that caused these slight variations could also cause major changes in plant and animal life. He theorized that in the battle to live, plants and animals most adapted to their environment would survive and pass on the survival traits to their offspring. Eons of little adaptations, he thought, could result in completely different species. 
	His evidence clearly showed that small evolutionary changes do occur, but his evidence for big changes was more speculative. But on the other hand, Darwin knew other biologists were working on the same idea, so he finally sat down and wrote "The Origin of Species." 
	It came out in 1859 and caused a furor since most people believed God created the plants and animals. Critics challenged him on the "infinitude of connecting links" he had predicted must exist. "Where are these links?" they asked. 
	The uproar died down as most scientists and others accepted Darwin's theory. 
	Since then theologians have had several responses to the theory. Most now accept that the earth is far older than 6,000 years, (the age proposed by Anglican Archbishop James Usher in the 16th century). Some accept evolution as the means by which God created life. Others accept a great age for the earth, but say the fossils do not show the gradual changes predicted by Darwin, but rather the sudden appearance of animals, as if created by a supernatural force. These would say the "days" of creation mentioned in the Bible are long ages. Yet others say God created a mature world with evidence of a past that never was, so brand new trees, for example, would have many annual rings.
^Deinonychus: Small But Deadly
100 Million BC;7-10 Feet;$175
MONTANA, UNITED STATES 
	Deinonychus was not very large, but it sure was deadly. In fact, some think that Deinonychus was one of the most ferocious dinosaurs ever. And that is easy to believe after seeing this movie! 
	Measuring only seven to ten feet long, these small, fast-moving predators could bring down dinosaurs many times their size. Scientists believe Deinonychus hunted in packs which would surround and overpower large dinosaurs such as slow-moving plant-eaters. Deinonychus was certainly well-adapted for hunting. It had fast, powerful thighs and a large head with sharp teeth that were perfect for biting off pieces of flesh and holding small prey in its mouth. 
	Deinonychus's most unique trait, however, was a single large curved claw found on both of its feet. When Deinonychus was walking or running, the claw was pulled back so it wouldn't interfere with the dinosaur's movement. But when Deinonychus was attacking, the claw was lowered so it could be used as a sharp weapon. Deinonychus likely grabbed its prey with its mouth and hands and tore at its victim's underbelly. 
	To maintain its very high level of activity, many scientists believe that Deinonychus had to have been a warm-blooded animal. A cold-blooded animal would have been too sluggish for Deinonychus' active lifestyle. 
	LOCALITY: Western USA 
	LENGTH: 7 - 10 Feet 
	WEIGHT: 175 Pounds
mPlants Invade the Land
400 Million BC

EARTH 
	About 400 million years ago the surface of the earth went through dramatic changes. The collision of the planet's shifting continents created large ranges of mountains which helped to raise the level of the land. As the water fell in many places the first plants began to invade the land. These were close relatives to seaweed and other ocean-going plant life. Without water surrounding them, however, these plants developed roots to absorb moisture from the ground, stems for support and a tough texture for their leaves in order to keep from drying out. The most primitive land plants were very small and mossy and stayed close to the shores of seas or lakes. 
	Sometime in the middle of the Devonian Period, about 345 to 400 million years ago, the first ferns appeared, initially without leaves and seeds. Gradually, these ferns developed leaves and very strong stems with some growing as tall as trees. 
	At the water's edge, something more amazing was taking place. Crabs, spiders, mites and other non-flying insects began to emerge. They thrived in the swampy jungles that were spreading across the earth's landscape.
Dimetrodon and Its Sail
270 Million BC;10 Feet;Unknown

NORTH AMERICA 
	How do you think Dimetrodon used this strange sail on its back? 
	Believe it or not, for a while some scientists thought it was actually for sailing; allowing Dimetrodon to sail across the water in search of food. 
	Dimetrodon, which literally means "two long teeth," had sharp teeth that look as if they would be good for eating fish, and Dimetrodon fossils have been found near ancient lake sites, so it seems reasonable to think that this creature ate fish, though it is also possible it ate other animals as well. 
	However, scientists no longer believe that the sail on its back had anything to do with sailing. Instead, they think that Dimetrodon could face the sail toward the sun to warm itself quickly, or turn the edge of the sail toward the sun to cool itself. Also, the sail may have been brightly colored and used to frighten rivals or predators, as well as to attract mates. 
	LOCALITY: North America 
	LENGTH: 10 Feet 
	WEIGHT: Unknown
HWhat Killed the Dinosaurs?
65 Million BC

BERKELEY, CALIFORNIA 
	What killed the dinosaurs? It's like a classic Sherlock Holmes mystery. Bodies have been found. There are all kinds of clues. Something killed a great many victims. But what? 
	The murders occurred 65 million years ago. The victims included the dinosaurs. In fact, not only were the dinosaurs killed off, but so were most other animals and plants. Fortunately, science often produces a Sherlock Holmes to solve its greatest mysteries, and one of them seems to have solved the mystery. 
	This modern detective is Nobel prize-winning physicist Luis Alvarez. His theory seems to explain many of the clues the killer left behind, buried with the dinosaurs in the rocks beneath our feet. Alvarez' theory is highly controversial, but it seems to be the best theory around. 
	Luis Alvarez's investigation of the case of the dead dinosaurs began several years ago when his son, Walter Alvarez, a geologist, pointed out a puzzle. There was an unexpected rare metal, iridium, found in some rock samples. 
	Iridium, a whitish-yellow metal, was named after the Latin word word for "rainbow" because of the colors it gives to liquids. Iridium is quite rare on Earth, yet was strongly present in the geologist's samples. Why? 
	The samples had been taken from the thin slice of Earth that occurs right above the layer where the dinosaurs died. Over Earth's billions of years, soil and rocks have rolled down mountains, been blown by wind and been carried by streams, depositing layer upon layer in valleys. 
	They found that, all over the world, the story seems to be the same: Below the iridium layer, dinosaurs and many other kinds of life flourished. Just above it, most of them are gone. Something weird must have happened when the iridium layer formed. Something that killed off most life on Earth. 
	But what could have done it? 
	Many theories have been proposed over the years. Some scientists think that Earth's climate turned cold, killing off most life. This was the most popular theory prior to Alvarez. But why did the climate change? Some think there was a tremendous eruption of volcanoes that polluted the air and water. 
	Luis Alvarez proposed a radically different theory. When his son discussed the iridium layer with him, Alvarez pointed out that there is one place where iridium is fairly common. It's not on Earth -- it's in space. 
	How do we know iridium is more common out there? Because meteorites (any rocky or metallic object that strikes the earth's surface) have lots of it. Earth rocks usually have little. 
	Most geologists are used to dealing with normal rocks, not space rocks. But Alvarez was used to thinking about space, so like Sherlock Holmes seeing the one clue that all the other detectives had overlooked, he deduced a connection between the dinosaurs and outer space. 
	Not only that, he was used to the idea of big explosions. He worked on the atomic bomb during World War II. If a meteorite killed off dinosaurs all over the world, it had to have been a big one. He knew that space is littered with big ones. Many of them are far bigger than the one that created Meteor Crater in Arizona, 1.2 kilometers (almost a mile) in diameter. 
	Alvarez, his son and other scientists began thinking about the details. How big would the meteorite have to be? What are the odds against such a big rock hitting the Earth in 65 million years? What would be the effect of the explosion? 
	And suppose it hit the ocean instead of land? What would it do to the atmosphere? How would it kill -- by heat, poisoning or some other way? 
	Above all, they had to compare the theory with the facts. Were there any known facts that contradicted the theory? If so, might the "facts" be wrong? 
	The scientists sat down and computed the effects of the biggest explosion the world had ever seen. 
	The blast must have been big enough to throw dirt thousands of miles. They figured that any meteorite much smaller than about ten kilometers (6 miles) in size would probably not be big enough to do the job. They estimated that there are enough ten-kilometer asteroids -- about the height of Mount Everest -- so that one of them ought to hit us every hundred million years or so. Asteroids much bigger than that are far rarer, so are not likely to have done the dirty deed. 
	What would happen if Mount Everest came crashing to Earth as fast as a typical meteorite (around 40 kilometers per second or 90,000 mph)? 
	It would be like millions of hydrogen bombs going off at once. Whether it hit land or water, it would shoot millions of tons of debris high into a high layer of the atmosphere, the stratosphere, where lighter particles float for years. Sunlight would be cut off as on a badly overcast day. The world would turn cold. 
	Since plants use sunlight to make food that animals eat, the plants would die and animals would starve to death. So that is how the dinosaurs probably died: Starvation. The mighty Brontosaurus, the fierce Tyrannosaurus, the armor-plated Stegosaurus -- they all died in a cold, dark world, their bellies crying for food. 
	Why didn't all life die out? Some seeds remained in the ground, waiting for the Sun to return. Some animals survived by eating the carcasses of other creatures. 
	In 1980, the Alvarez group published their ideas in the journal "Science" and triggered a storm of controversy. Many geologists, who normally ignore astronomy, thought it was ridiculous. Astronomers, on the other hand, welcomed the theory with open arms. They're always happy to find that their research applies to Earth. 
	The debate has continued. More and more evidence has been found supporting the Alvarez theory, and now even many geologists accept it. Astronomers have come to prefer the idea that comets killed the dinosaurs, rather than meteorites. They would have roughly the same effect, but Earth has probably been hit by more comets of this size than meteorites, so it's still basically the Alvarez theory. 
	Where's the crater? There's evidence that it's in the Yucatan province of Mexico, largely covered up by dirt and jungle. This is often called the "smoking gun" of the Alvarez theory -- the evidence that could convict the astronomical dinosaur killer.
!Diplodocus: Light As A Feather?
150 Million BC;100 Feet;11 Tons

UTAH, UNITED STATES 
	Diplodocus was an enormous dinosaur that grew as long as 100 feet. But most of this length was taken up by its incredibly long neck and even longer tail. In fact, Diplodocus' body accounted for only about 13 feet of its entire length while its tiny head measured only two feet. 
	Diplodocus lived during the Late Jurassic Period and probably traveled in herds around what is now Colorado, Montana and Wyoming, feeding on the lush vegetation that thrived at the time. Though Diplodocus was a huge animal, it only weighed 11 tons, about one-eighth the weight of its 75-foot long cousin Brachiosaurus. Diplodocus was much lighter than other large plant-eating Sauropods because its bones were hollow. 
	When Diplodocus was hungry it could stand up on its rear legs and, using its huge tail for balance, stretch to nearly 50 feet above the ground in order to feed on the very tops of trees -- about 29 feet higher than today's giraffe can reach! 
	LOCALITY: Colorado, Montana, Wyoming and Utah, USA 
	LENGTH: 100 feet 
	WEIGHT: 11 tons 

QThe Little Plan of Life


CAMBRIDGE, ENGLAND 
	From dinosaurs to you, there is a tiny set of plans for every living thing. It's a chemical called DNA. 
	DNA, which stands for deoxyribonucleic acid, comes in long strands that inhabit the nucleus of every living cell. 
	It is like a long spiral staircase made up of about three billion steps. 
	Although DNA is often called the blueprint for life -- because it is like plans from which a building is made -- it's more like a computer program. Computer programs consist of line after line of simple statements: move X to Y, subtract T from Z, erase W, jump to line 17. The DNA is just like this. Each stair step is a line in the code. It's something like the Morse code that is used for the telegraph. Individually, each part looks pretty simple, but put it all together and it spells "dinosaur," "flower," or "human being." 
fEarth On The Move
400 Million BC

EARTH 
	Ever since the earth's formation, 4.6 billion years ago, the surface of the planet has not stopped moving. That's hard to believe when you consider how enormous the earth's continents and oceans are. Yet, beneath the surface of the planet lie massive plates of rock which move ever so slowly over the earth's molten core. As these plates move they carry the continents with them, sometimes in very different directions. This is what scientists call "continental drift." Over hundreds of millions of years, the slow movement of these plates has caused the earth's continents to gradually shift their positions all over the planet. 
	Of course, this movement is so slow that it is almost impossible to detect except with the most precise scientific instruments. However, it is possible to see the effects of these shifting plates all around us. For instance, when plates collide into one another or grind past each other they push up layers of rock and earth on the planet's surface, creating mountains. Other times, the friction of two plates rubbing against one another can cause an earthquake. The large earthquakes that frequently strike California are the result of two enormous plates grinding against each other. Eventually, it is said, Southern California will slide so far to the northwest that it will become an island or peninsula near the San Francisco Bay area.
Earth As We Know It
50 Million BC

EARTH 
	Just as the dinosaurs began to vanish from the earth, the modern continents had finally begun to take shape. Australia and Antarctica had broken off of South America. India had moved north until it pressed into Asia, forming the Himalayan mountain range. North America, South America and Europe had begun to take up their positions on either side of the globe. With the continents separated now, the plant and animal life began to develop very differently from place to place.
QOne Thousand And One Teeth
70 Million BC;43 Feet;2.9-3.9 Tons

MONTANA, UNITED STATES 
	Edmontosaurus was one of the largest of the duckbilled hadrosaurs which foraged for plants in the ancient forests of what is now western North America. This 43-foot long dinosaur had a broad, flat snout with a horny covering, and a large, toothless beak that looked very much like a duck's bill. While its bill was quite toothless, Edmontosaurus' inner jaw contained many banks of teeth. These teeth were tiny, sharp, and perfect for grinding up plants and tough vegetation. As soon as they wore down, new teeth would grow quickly in their place. Edmontosaurus probably had more than 1,000 teeth in its mouth at any given time. 
	Edmontosaurus' jaw was similar to that of Iguanodon. Both dinosaurs could move their jaws from side to side, making it much easier to grind and pulverize the fibrous plants that made up their diets. 
	One of the stranger features of Edmontosaurus was its huge nostrils. Paleontologists believe these nostrils could have been covered with large flaps of loose skin. This skin could have been inflatable, allowing Edmontosaurus to make loud, bellowing noises. These inflatable nostrils could also have been brightly colored and used during mating season, or as a way for individual Edmontosaurus' to recognize each other. 
	LOCALITY: Alberta, Canada; Montana, USA 
	LENGTH: 43 Feet 
	WEIGHT: 2.9 - 3.9 Tons
Finding Dinosaur Eggs
1922-1925 AD

GOBI DESERT, MONGOLIA 
	Since dinosaurs were reptiles it was logical to assume that they laid eggs. Yet, for many years no one was able to discover any evidence to prove that point. That was easy enough to explain. Dinosaur eggs would be too fragile to form a fossil, except under the most unique circumstances. 
	Then in 1922, an expedition to Mongolia sponsored by the American Museum of Natural History made an amazing discovery. The very first nests of dinosaur eggs were unearthed in the sands of the vast Gobi Desert. 
	Between 1922 and 1925 scientists discovered more than 50 fossil eggs belonging to Protoceratops at the Gobi Desert site. Some of these were broken bits of shell, but others were remarkably preserved, whole eggs. Most of these eggs were found intact in sand nests which were shallow, scooped out depressions in the sand that were arranged in a circular pattern. It is thought that the Protoceratops mother must have turned her body around in a circular motion as she laid her eggs. Some nests held remains of over 34 eggs, leading paleontologists to believe that female Protoceratops' must have shared their nests with other females, since no single mother could have laid that many eggs. 
	These Protoceratops eggs were about eight inches long, and were a little more elongated than the birds' eggs we know today. The shell was tough and its surface was wrinkly and rough to the touch.
rElasmosaurus: Longest Marine Reptile
100 Million BC;46 Feet;Unknown

KANSAS, UNITED STATES 
	Measuring 46 feet in length, Elasmosaurus was the longest known plesiosaur, or marine reptile, to roam the seas of the Cretaceous era. Elasmosaurus' neck alone measured close to 26 feet, more than half its body length! This snake-like neck was made up of more than 71 vertebrae and was three times longer than that of any of its near relatives. 
	The rest of Elasmosaurus' body was sturdy and compact. Its tail was short, and its huge, paddle-like flippers were perfect for propelling Elasmosaurus through the water, much like a sea turtle does. Scientists think that Elasmosaurus spent much of its time swimming with its head just above water, scanning the waves for small fish and squid to eat. Like Plesiosaurus, Elasmosaurus probably only left the water to lay its eggs in the sand.   
	LOCALITY: Kansas, USA; Japan 
	LENGTH: 46 Feet 
	WEIGHT: Unknown 
Euoplocephalus: All Secure
80 Million BC;18 Feet;2 Tons

ALBERTA, CANADA 
	With all of its heavy armor and thick bones, Euoplocephalus seems like it would be slow and clumsy. Quite the contrary. Because its armor plating developed in narrow bands, Euoplocephalus was quite agile for a dinosaur of its size and mass. 
	Living up to the end of the Cretaceous Period, Euoplocephalus was one of the largest of the armored dinosaurs known as ankylosaurs. It weighed close to two tons and measured 18 feet in length. Bands of armor were embedded in its back and covered with large, bony knobs. There were also pointed spikes at the back of its head, over its shoulders and at the base of its tail. Like its close relative Ankylosaurus, even its eyelids were armored with bony plates that slid down to protect the eye socket when the dinosaur was in combat. 
	In combat, Euoplocephalus must have been quite a fighter. Even its natural enemy, the powerful Tyrannosaurus, would have had a tough time breaking through Euoplocephalus' heavy body armor. Meanwhile, Euoplocephalus would try to scramble around until it could swing the massive bony club at the end of its tail toward Tyrannosaurus' legs and stomach. A direct hit was often fatal. 
	LOCALITY: Alberta, Canada 
	LENGTH: 18 feet 
	WEIGHT: 2 tons 

EFrom Dust Cloud to Our House
4.6 Billion BC

EARTH 
	Way out in the boondocks of the Milky Way Galaxy about 4.6 billion years ago, a cloud of gas and dust began to come together into a rotating disk, attracted by its own gravity. 
	As this disk formed, gravity squeezed a large lump of gas at the center so hard that the hydrogen atoms began to fuse together, creating a nuclear reaction and igniting the fires of our sun. 
	Orbiting the sun, other clumps formed, eventually becoming planets, one of them the Earth. Those close to the sun -- Mercury, Venus, Earth and Mars -- became small and rocky planets. Those farther away mostly became large gas-covered planets: Jupiter, Saturn, Uranus and Neptune. 
	When Earth was first formed, you couldn't have lived on it. It was extremely hot and there was no oxygen to breathe. It took a long time for our planet to be ready for plants, animals and people. 
	Though Earth was once very hot on its surface, today it has cooled. But the natural radioactivity of rocks keeps the insides of our planet hot. Large sections of the Earth's surface drift around slowly, as you see illustrated here.
Life: How Did It Happen?
4 Billion BC

EARTH 
	In this illustration, you can follow what might be the history of life on Earth. 
	In the sky, you see the development of galaxies similar to the Milky Way. There are the comets, planets and moons that formed in the solar system. And the rays of our star, the Sun, send us the energy that life depends on. 
	In the ocean at the far left, the molecules that were the original building blocks of life are forming. As you look to the right you can see the bacteria that were the first cells of life, followed by more sophisticated sea life. Amphibians were able to climb out of the sea and walk on land, and finally they led to land animals like dinosaurs, and later, to humans. 
	This is the story the fossils show us, but how did it happen? 
	For a long time the religious explanation was the most widely held theory. In other words: "God made the plants and animals." It wasn't until naturalist Charles Darwin published his book, "The Origin of Species," that anyone came up with a persuasive natural explanation. 
	Darwin proposed that life evolved by a series of accidental little changes, called mutations. Most of them didn't help the plant or animal survive. Some even hurt. But some of them were beneficial. 
	So, for example, some dinosaurs might have evolved their long necks to reach the leaves at the tops of trees. Baby dinosaurs who happened to be born with longer necks would be better able to eat from the tops of tall trees and would be better able to survive and have long-necked children of their own.
Universe at a Glance
15 Billion BC

UNIVERSE 
	In this artist's illustration you can follow scientists' current understanding of the steps that occurred in the formation of the universe. 
	At the far left is the Big Bang, the explosion that marked the beginning of the universe. Why the bang occurred and where the material came from that exploded is still unexplained by science, but what follows is more clear. 
	To the right of the Big Bang you can see the great stretches of hydrogen that made up the early universe, and following it, the condensation of hydrogen into large clouds, and then into an early star, one of billions. 
	In the next image you can see our solar system begin forming, and then, finally, Earth. 
0How To Make A Fossil


    Everything we know about dinosaurs comes from studying the fossils they left behind. Not every animal or plant that died in the distant past created a fossil. Usually, whatever was left of a dead animal was eaten by scavengers or gradually dissolved into the earth by the forces of air and water. Occasionally, however, the conditions were just right to transform certain parts of an animal's body into a fossil that could be preserved for hundreds of millions of years. 
	The most frequent way for that to happen was if an animal's body ended up in a place where it would be quickly covered with layers of sediment or sand, therefore protecting it from decay. 
	The most likely place for this to happen was on the sandy bottom of the sea or a lake or river. Many times, dinosaurs that died by rivers or lakes were washed away by the water to a sandbar or sank to the water's bottom where their bodies were covered with soft sediment. It is also possible for dinosaurs to be fossilized in deserts where the fast-blowing sand could quickly cover up a body. 
	In either case, the soft parts of the dinosaur like the skin, muscles and organs eventually dissolved, leaving the harder parts like the skeleton and teeth preserved. Over the years, as more and more sediment covered the dinosaur's remains, minerals replaced the material of the bones or teeth and left a hardened duplicate of the original bone. 
	Usually, the hardest parts of an animal were the only parts fossilized, but sometimes the soft tissue such as the skin or muscle could be preserved in their original state.
The Mystery of Life
1 Billion BC

EARTH 
	The first thing to remember about simple life forms is that there is nothing simple about them. The most basic cell has been compared to a factory carrying out as many functions as every type of factory on Earth put together. 
	Therefore, it is still something of a mystery how living things were first formed, but many scientists believe that in Earth's early ages rain carried chemicals from the air and ground into the oceans, making a salty soup out of which life evolved. 
	Though the molecules that make up living things are much more complicated than those found in the primitive oceans, experiments have shown that when acted upon by certain sources of energy, chemicals found on the young Earth could have produced the amino acids and nucleotide bases, which are to life as bricks, for example, are to buildings. Other theories suggest that these building blocks could have hooked together into more complicated proteins and nucleic acids to form "protocells," precursors to true living cells. 
	Some scientists theorize that after eons of reacting with each other and with other chemicals, protocells somehow developed skins that could absorb chemicals and grow larger without bursting. Gradually, over many generations, surviving protocells became more complex until some of them were able to grow and then split into two identical copies of the original cell, at which point they would be alive. 
	But other scientists, such as Nobel Prize winning biochemist Francis Crick, consider this chain of events so vastly improbable that they speculate early life forms may have drifted in from outer space. 
	Scientists are still searching for definite answers to the complex mystery of life. 
cTreasure of the Orient
1922 AD

GOBI DESERT, MONGOLIA 
	By the 1920s, scientists around the world were caught up in a frenzy to find clues to the origins of man. So in 1922, the American Museum of Natural History sent a huge expedition to Mongolia in the hopes of unearthing fossils of primitive man and prehistoric mammals. What they discovered instead was a vast and varied collection of dinosaur fossils, some of which had never been seen before. 
	The fossils were located in a sandy basin in the forbidding Gobi Desert where temperatures can range between 100 degrees in the summer and negative 100 degrees in the winter. Between 1922 and the present, numerous expeditions have been to the Gobi, uncovering entirely new species of dinosaurs, including Oviraptor, Stegoceras, Protoceratops and Velociraptor. In some of these cases, the fossils were found resting on the surface, covered only by a layer of fine dust. 
	One of the most fascinating fossil finds from the Gobi Desert excavations was a group of nearly perfectly preserved fossil eggs of Protoceratops, a small horned dinosaur related to Triceratops. The eggs were found arranged in a small depression in the ground that must have served as a nest. They were oval-shaped and not much larger than a human hand. 
	In the same area, scientists eventually discovered Protoceratops' fossils of all ages, from tiny hatchlings to full-sized adults. 

Hips Make the Dinosaur
225 Million BC

EARTH 
	One of the most important differences between early reptiles and dinosaurs is the structure of their hips. As dinosaurs evolved from ancient reptiles, they needed to develop new places on their bones to attach the powerful muscles which would swing their large hind legs. 
	As a result, two kinds of dinosaurs evolved. One group was called saurischian or "reptile-hipped" dinosaurs and the other was called ornithischian, which means "bird-hipped." In fact, all dinosaurs can be divided into one of these two groups. 
	Dinosaur hips were made up of three bones that could be found on each side of the pelvis: the ilium, the ischium, and the pubis. In reptile-hipped dinosaurs the ischium pointed backwards and the pubis pointed forwards. With reptile-hipped dinosaurs, the joints and connections between the hip and leg bones were much simpler than its predecessors and made it possible to carry the dinosaur's legs directly beneath its body. In this fashion, the legs acted like the pillars of a building, capable of holding up a substantial amount of weight. 
	In the category of reptile-hipped dinosaurs, there were both meat- and plant-eaters, including Tyrannosaurus as well as Diplodocus. 
	Bird-hipped dinosaurs, on the other hand, were all plant eaters. Their hips were different from reptile-hipped dinosaurs because their pubis pointed backwards along with the ischium. Bird-hipped dinosaurs included some of the more distinctive-looking dinosaurs, such as the heavily armored Ankylosaurus, Stegosaurus and the crested Corythosaurus.
Ichthyosaurus: Acrobat of the Seas
150 Million BC;33 Feet;Unknown

GERMANY 
	Ichthyosaurus looked like a fish, swam like a fish but, in fact, was a reptile. 
	For nearly 80 million years, Ichthyosaurus cruised the open seas feeding off of schools of primitive fish which lived in the shallow waters surrounding the ancient continents. With its dorsal fin, streamlined body and strong, flexible tail, Ichthyosaurus resembled a modern dolphin. Like dolphins, Ichthyosaurus was probably quick and capable of impressive acrobatics both in and out of water. Also like a dolphin, Ichthyosaurus couldn't remain underwater forever and had to break the surface from time to time in order to breathe. To locate its prey, Ichthyosaurus had large eyes and heavy ear bones which transmitted the sounds of the sea. Over the years, scientists have found hundreds of well-preserved fossil Ichthyosaurus in rocks around Europe and North American. 
	Much of that land was once covered by water, so when an Ichthyosaurus died its body would descend to the sea floor where it would be covered with sediment and transformed into a fossil. One of the most amazing traits of Ichthyosaurus was that it gave birth to live young rather than lay eggs like other reptiles. Many fossils of Ichthyosaurus have been discovered with young Ichthyosaurus inside the skeleton of an adult. Some fossils even show the body of the baby Ichthyosaurus in the process of emerging from an adult body. 
	LOCALITY: Germany 
	LENGTH: 10 - 33 Feet 
	WEIGHT: Unknown
Iguanodon: Not an Iguana
125 Million BC;30 Feet;5 Tons

BERNISSART, BELGIUM 
	In 1809 part of an Iguanodon's giant shinbone was found in southern England. In 1819, some teeth and other bones were discovered and scientists at the time thought that they probably belonged to a gigantic mammal, like a rhinoceros. But then the geologist Gideon Mantell noticed that the teeth resembled those of a modern iguana, so he named the creature Iguanodon. Iguanodon was the second dinosaur to be discovered even though the word "dinosaur" had yet to be coined. 
	Iguanodon stood about 16 feet tall, measured 30 feet long and weighed close to five tons. It roamed the warm, humid Cretaceous landscape and fed on the rich abundance of plant life covering the land. Large numbers of Iguanodon skeletons have been found in England, Belgium and Germany, indicating to paleontologists that Iguanodon probably traveled in large herds. 
	Iguanodon had small "hooves" on its hands and feet, and its legs were long and sturdy. This giant dinosaur probably spent most of its time on all fours, although it could have stood on its back legs to reach for higher bushes and plant life. 
	LOCALITY: Western Europe, Mongolia, North Africa, Western North America 
	LENGTH: 30 Feet 
	WEIGHT: 5 Tons
Library, Bibliography, Museums


LIBRARY 
	Welcome to the Dinosaur Adventure Library! You can use the card catalog in the library picture to find any topic you wish. 
	Just click on the card catalog drawer containing the topic you want to find, then click on the topic itself. Dinosaur Adventure will take you right to a screen on that topic. 
	Below are lists of dinosaur books and museums. 
	BOOKS 
	-- The Big Book of Dinosaurs, Attmore, Stephen. Brimax Books Ltd., 1990. Elementary level book on dinosaurs and Earth's early ages. 
	-- The Big Golden Book of Dinosaurs, Elting, Mary. Western Publishing Company, 1988. Color pictures and brief text. For elementary school children. 
	-- Children's Guide to Dinosaurs and Other Prehistoric Animals. Whitfield, Philip. 1992, Marshall Editions Developments Limited. Bright, colorful pictures and easy to read facts characterize this child's level book. 
	-- Dinosaurs: A Global View. Czerkas, Sylvia J. and Czerkas, Stephen A., Dragon's World Ltd. 1990. Adult level. Using mostly text and some pictures, this book describes different time periods during which dinosaurs thrived, facts about the earth's atmosphere, and anatomy of the dinosaurs. 
	-- Dinosaur Babies, National Geographic Society, 1991. Action pop-up pictures on every page, along with information on pronunciation. 
	-- Dinosaur Bones! Thompson, C.E. Grosset and Dunlap, 1992. Fun book for early elementary school students. Contains activities, punch-out dinosaur pictures and easy facts. 
	-- The Dinosaur Data Book: Facts and Fictions About the World's Largest Creatures. Lambert, David and The Diagram Group. David Lambert and Diagram Visual Information Ltd. Adult level. Lists dinosaur types, the meaning of their names, and facts about their different body parts. 
	-- The Dinosaur Encyclopedia. Benton, Michael, PhD. Kingfisher Books Ltd., 1984. Adult level. Provides exhaustive list of dinosaurs, along with pictures, general facts, and pronunciation of each dinosaur name. 
	-- The Dinosaur Question and Answer Book, Funston, Sylvia. Greey de Pencier Books, 1992. Numerous questions are presented and answered in this book. Subjects cover dinosaur exploration, paleontologists, fossils, and humor, such as, "Which dinosaur would make the best pet?" 
	-- The Dinosaur Who Lived In My Backyard, Hennessy, B.G. Penguin Books USA, Inc. 1988. Early elementary-school level story of a youngster and his dinosaur. 
	-- The Great Dinosaur Atlas, Lindsay, William. Dorling Kindersley, 1991. Colorful, accurate illustrations and explanations of dinosaurs. 
	-- The Illustrated Encyclopedia of Dinosaurs. Norman, David PhD. Salamander Books, Ltd., 1985. Comprehensive, illustrated adult-level discussion of dinosaurs. 
	MUSEUMS 
	-- Academy of Sciences of Mongolia; Ulan-Bator, Mongolia. 
	-- Argentine Museum of Natural Sciences; Buenos Aires, Argentina. 
	-- Australian Museum; Sydney, New South Wales, Australia. 
	-- Bernissart Museum; Bernissart, Hainaut, Belgium. 
	-- British Museum (Natural History); London, England. 
	-- Carnegie Museum of Natural History; Pittsburgh, Pennsylvania. 
	-- Cleveland Museum of Natural History; Cleveland, Ohio. 
	-- Denver Museum of Natural History; Denver, Colorado. 
	-- Dinosaur National Monument; Vernal, Utah. 
	-- Field Museum of Natural History; Chicago, Illinois. 
	-- Geological Museum at the University of Wyoming; Laramie, Wyoming. 
	-- Museum of Natural History; Princeton University, Princeton; New Jersey. 
	-- Museum of Paleontology; University of California, Berkeley; California. 
	-- Museum of the Rockies; Montana State University; Bozeman, Montana. 
	-- National Museum of Natural History; Paris, France. 
	-- Natural History Museum; Humboldt University; Berlin, Germany. 
	-- Natural History Museum of Los Angeles County; Los Angeles, California. 
	-- Peabody Museum of Natural History; Yale University, New Haven, Connecticut. 
	-- Provincial Museum of Alberta; Edmonton, Alberta, Canada. 
	-- Utah Museum of Natural History; University of Utah, Utah.
Looking For Dinosaurs
1992 AD

    Most of the dinosaur fossils that exist in the world today are buried beneath hundreds of feet of earth that has built up over millions and millions of years. That makes finding dinosaur fossils no easy task. 
	So how do the scientists who study dinosaurs, generally known as paleontologists, find their fossils? Very often purely by accident. The ground or rock around a fossil may have eroded enough to expose a part of the fossil. Sometimes, people like miners will stumble upon a collection of fossil remains while they are digging through layers of rock. 
	More often than not, paleontologists find dinosaur fossils by playing detective. The first place they look is where the rock is as old as a dinosaur would be. That means between 65 and 210 million years. Then, since most fossils were created when layers of sediment from a river or lake covered a dinosaur's body, they look in places where there is sedimentary rock. 
	Usually the sides of river canyons are the best places to start because the layers of rock are well exposed. Other good places can be where scientists suspect rivers or large bodies of water may have existed hundreds of millions of years ago.
Maiasaura: Good Mother Dinosaur
100 Million BC;30 Feet;Unknown 

MONTANA, UNITED STATES 
	The discovery of a large number of Maiasaura fossils has given scientists new insight into the social behavior of dinosaurs. It turns out the duck-billed Maiasaura liked to hang out together and take care of their young. 
	There are two major clues scientists have used to come to these conclusions. One is a vast boneyard that scientists have discovered in western Montana. The area is filled with as many as 10,000 skeletons of one particular kind of hadrosaur, the Maiasaura. Also, these skeletons range from about 10 feet long to 23 feet long, suggesting this herd was made up of different age Maiasaura. Apparently they had died from the smoke and fumes and ash of an exploding volcano. 
	This is significant because it shows Maiasaura was not a loner, but lived together in herds. 
	Another significant find in Montana was a nest of 15 baby Maiasaura. The babies were about three feet long, three times the size they were when they were born. (Scientists know newborn Maiasaura are about a foot long from other nests.) 
	Why weren't these big strapping young dinosaurs out on their own? Most reptiles are ready to face the world the moment they are born. 
	This is the question scientists had, and there are two possible answers, both which suggest these dinosaurs had a strong family relationship. 
	Either the parents brought food to the young dinosaurs or the young dinosaurs went out for food and then returned to the nest. Both these possibilities suggest a strong family relationship between parents and children. 
	No wonder the word "Maiasaura" means "good mother lizard". 
	LOCALITY: Montana, USA 
	LENGTH: 30 Feet 
	WEIGHT: Unknown 
Mammoth: The Hairy Elephant
1 Million BC;Unknown;Unknown

ALASKA, UNITED STATES 
	Mammuthus Primigenius is better known as the "Woolly Mammoth," and belongs to the same family as the modern elephant. Mammuthus Primigenius was a familiar sight to early cave dwellers, who painted images of the hairy creature on cave walls and rock formations in France and Spain. 
	Few mammals were better built for cold climates than Woolly Mammoth. It had a thick shaggy coat of long black hair, and a fatty hump. The hump was a storage place for extra nutrition during the long, cold winter months when vegetation was scarce. Its long ivory tusks curled upward and were probably used for scraping ice and snow from the ground to uncover any edible vegetation. 
	Mammuthus Primigenius survived until about 10,000 years ago. Paleontologists believe its extinction was due to over-hunting by humans, as well as the general warming of the climate after the end of the Ice Age. The only two species of this family to have survived are the Indian and African elephants. 
	LOCALITY: Alaska, USA 
	LENGTH: Unknown 
	WEIGHT: Unknown
Megazostrodon: The First Mammal
208 Million BC;5 Inches;Unknown

LESOTHO, AFRICA 
	Contrary to popular belief, mammals appeared on the earth almost as long ago as dinosaurs. In fact, tiny shrew-like animals such as Megazostrodon were alive throughout the entire age of dinosaurs, scurrying among the legs of the giant Apatosaurus and ducking for cover when the voracious meat-eater Coelophysis came hunting for food. 
	These early mammals were small and furry and looked a lot like modern mice. They were also warm-blooded and suckled their young babies. Despite these many mammal-like characteristics, it is thought they still laid leathery eggs. 
	Mammals like Megazostrodon may have evolved from a special group of reptiles during the late Triassic or early Jurassic Period, some 208 million years ago. During that time, these animals developed traits that made them well-suited for a highly active lifestyle. As opposed to having only one kind of teeth, as most reptiles did, early mammals developed four types. Their skeletons changed so that their limbs were more flexible and able to move more quickly. Also, mammals developed a shorter rib cage and larger lungs which could inhale and exhale more rapidly. Most importantly, though, mammals like Megazostrodon became warm-blooded, which meant they relied on the food they ate for sustaining their body temperature rather than the outside environment. That enabled mammals to maintain a higher level of activity throughout the day than cold-blooded reptiles could. 
	Megazostrodon's diet probably consisted of small insects and reptiles, and scientists believe that Megazostrodon did most of its hunting and scavenging during the night to avoid being eaten by hungry meat-eating dinosaurs! 
	LOCALITY: Lesotho, Africa 
	LENGTH: 5 Inches 
	WEIGHT: Unknown 
Meteor vs. Dinosaurs
65 Million BC 

EARTH 
	Could the impact of a giant meteor striking the earth have caused the sudden extinction of the dinosaurs? Some scientists think so. 
	Meteorites, which are pieces of rocks from space, have always collided with the earth. Enormous craters like the one in this picture are proof that very large meteors have indeed struck the earth in the distant past. 
	It's very possible, think some, that a massive meteor measuring six to nine miles wide may have hit the planet sometime at the end of the Cretaceous Period. The force of the impact from such a meteor would have created a crater nearly 100 miles wide. It also would have made an enormous explosion, sending huge amounts of dust and debris into the atmosphere. In a very short time, the skies around the world would have been covered by a blanket of dust, blotting out much of the sun's rays. This could have lasted for several months or even years. 
	Without sunlight, the temperature around the earth would have quickly dropped below freezing, killing plants as well as animals. If enough plants were killed, then the food for many dinosaurs would have disappeared. Also, without plants, eventually the level of oxygen would have declined, suffocating dinosaurs and other animals.
The President Protects Fossils
1909 AD

VERNAL, UTAH 
	When a young scientist named Earl Douglass spotted a massive Diplodocus thigh bone resting on a sandstone ledge near Vernal Utah, he had no idea he was on the verge of one of the richest fossil finds in history. Douglass, who worked for the Carnegie Museum in Pittsburgh, returned to the site a year later hoping to uncover the rest of what turned out to be a 70-foot long Diplodocus skeleton. As Douglass and others began to excavate, they soon discovered thousands of dinosaur bones lodged in the stone around the skeleton. 
	For the next 13 years, the Carnegie Museum sent one excavation team after another to the stone quarry, unearthing the first complete skeletons of giant plant-eaters such as Apatosaurus, Diplodocus and Camarasaurus. They also found the bones of Stegosaurus and the meat-eating Allosaurus which must have preyed on the slower-moving plant-eaters millions of years ago. 
	Later, however, when amateur fossil hunters began combing the land around the quarry in search of more bones, President Woodrow Wilson turned the site into a national park in order to protect the fossils from any damage. Today, visitors can go to Dinosaur National Monument, as it is now called, and see a long wall of stone filled with dinosaur bones still in their original resting place.
The Ostrich Dinosaur
75 Million BC;13 Feet;Unknown

ALBERTA, CANADA 
	This dinosaur looks something like an ostrich. It has long, powerful legs that look like they were built for running, no teeth and may even have had a beak. 
	Of course, Ornithomimus (which means "bird mimic") isn't really related to the ostrich. Unlike the ostrich, it had a long tail that made up about half of its 13-foot length, and instead of wings, it had arms and hands. 
	Scientists think Ornithomimus may have eaten small plants and animals. 
	LOCALITY: Alberta, Canada 
	LENGTH: 13 Feet 
	WEIGHT: Unknown
ZOviraptor: Eggs Over Easy
80 Million BC;6 Feet;Unknown

GOBI DESERT, MONGOLIA 
	The first complete fossil of Oviraptor was discovered in Mongolia just a few feet from a nest of fossilized Protoceratops eggs. It is very likely that the Oviraptor was about to make a meal of the eggs when an angry adult Protoceratops caught it in the act and killed it. For that reason Oviraptor got its name, which means "egg thief." 
	Oviraptor was an unusual dinosaur. Measuring five to six feet long, it had a short head and a massive pair of toothless jaws shaped like a beak. With strong muscles in its mouth, Oviraptor must have had a powerful bite which was useful for breaking through hard surfaces, such as the eggs of other dinosaurs. Another interesting feature was a unique crest above Oviraptor's snout which was full of air passages and openings for its nose. 
	LOCALITY: Mongolia 
	LENGTH: 6 Feet 
	WEIGHT: Unknown
oOwen: This Is No Lizard!
1841 AD

ENGLAND 
	By 1841, several major dinosaur fossil discoveries had been made around England. Yet, most of the scientists who studied them believed they were nothing more than members of a group of giant lizards. That is, until Sir Richard Owen took a closer look at the evidence. 
	Owen was a famous British anatomist who studied the physical relationships between different groups of animals. When Owen studied the three most important fossil discoveries at the time, he quickly concluded that the bones were not at all like the bones of any lizard alive at the time. In fact, they were so different that he believed the fossils must have come from an entirely different group of animal which had long since vanished from the earth. He called this new group of animal "Dinosauria" which meant "terrible reptile." 
	Owen described these creatures as being giant elephant-like reptiles which lumbered clumsily on all fours. Eventually, Owen published his findings in a book which created an enormous stir in England where people were fascinated to discover that a race of huge animals inhabited the earth long before there were people. 
Parasaurolophus: The Trumpeter 
80 Million BC;33 Feet;$8000

ALBERTA, CANADA 
	Of all the dinosaurs in history, Parasaurolophus must have had one of the most distinctive-looking heads. The crest of this 33-foot long duck-billed dinosaur measured almost six feet in length and was made of a strong but hollow tube filled with nasal passages. These nasal passages connected from the creature's nostrils back to the very tip of the crest. 
	When scientists first discovered Parasaurolophus, it was thought that the crest was used as a kind of snorkel, but that could not have been farther from the truth since the tip of the crest didn't have an opening in it! There are plenty of other theories for how Parasaurolophus might have used this oddly shaped crest. It could have been used like a trumpet, making sounds to warn others of danger or to attract mates. These dinosaurs, which traveled in herds through the jungles of North America, had very good eyesight and may have used their unique headgear as a form of identification. 
	LOCALITY: New Mexico, Utah, USA; Alberta, Canada 
	LENGTH: 33 Feet 
	WEIGHT: 4 Tons
VDiplodocus' Rake Teeth
150 Million BC
WYOMING, UNITED STATES 
	Imagine eating with just your front teeth. That's what Diplodocus did. 
	The giant Diplodocus, which grew up to 100 feet long, had a set of weak, pencil-like teeth in the front of its jaws only. 
	You can see them here. Notice how dull they are compared to the powerful,  sharp teeth of the meat-eating dinosaurs. 
	Because it didn't have back teeth, scientists believe Diplodocus must have used its teeth mostly to rake leaves off of trees and then swallowed its food unchewed. 
	Perhaps stones that Diplodocus had swallowed earlier would have helped it digest its food. 
bPlateosaurus: First Large Dinosaur
200 Million BC;23 Feet;Unknown

TROSSINGEN, GERMANY 
	Plateosaurus, or "flat reptile," was one of the first large plant-eating dinosaurs known as "prosauropods". These were the ancestors of the much larger "sauropods," which includes Brachiosaurus and Apatosaurus. 
	Plateosaurus lived during the Late Triassic and Early Jurassic Periods and ranged all over what is now northern Europe. At a major fossil site in Germany dozens of Plateosaurus skeletons have been uncovered at the same location, leading some 
	scientists to believe that this dinosaur traveled in large herds as it browsed among trees and bushes which were its food. 
	Plateosaurus measured up to 23 feet long, with a tail that made up almost half its length. Plateosaurus had a rather small head compared to the rest of its body. Its many leaf-shaped teeth had large, coarse serrations very similar to modern 
	plant-eating lizards. 
	Plateosaurus probably spent most of its time walking around on all fours, though occasionally it reared up on its strong back legs to nibble at the tops of trees. 
	LOCALITY: England; France; Germany; Switzerland 
	LENGTH: 23 Feet 
	WEIGHT: Unknown 
_Plesiosaurus: Reptile of the Sea
200 Million BC;7 Feet;Unknown

GERMANY 
	Plesiosaurus was the earliest member of the ocean-going group of reptiles called Plesiosaurs. These seven-foot-long marine reptiles cruised the shallow seas around England and Germany in search of their prey: smaller fish. Instead of limbs like other reptiles, Plesiosaurus developed long, narrow penguin-like flippers and short tails. 
	Plesiosaurus, or "ribbon reptile," used its paddle-shaped flippers much like a sea turtle does. Instead of rowing backwards and forwards, Plesiosaurus flapped its paddles up and down so that it probably looked like it was "flying" through the water when it swam. Plesiosaurus also laid its eggs just like a sea turtle does, in nests that were dug out in the sand. Because of their long necks and lack of any protective "armor," they would have been easy prey for enemies as they waddled up the beach to lay their eggs. 
	Plesiosaurus was an expert fish-catcher. Held high above the water with its long neck, Plesiosaurus' head could spot fish beneath it, and then snap them up with its razor sharp teeth. 
	LOCALITY: England; Germany 
	LENGTH: 7 feet 
	WEIGHT: Unknown 
FHow the Solar System Started
4.6 Billion BC

SOLAR SYSTEM 
	Though the details are not fully understood, it appears our solar system started about 4.6 billion years ago as a whirling disc of hot hydrogen gas mixed with heavier atoms from ancient supernova explosions. 
	Gravity pulled the hydrogen together, toward the center of the disc. The hydrogen became more and more compressed until a nuclear fusion reaction began, generating energy. The Sun was born. 
	The remaining tenth of a percent of solar material condensed into smaller bodies that eventually became the planets. Leftovers became moons, comets, and asteroids.
PEarth Comes Alive
1 Billion BC

EARTH 
	Close to 2.5 billion years ago, the earth's surface and atmosphere were stable enough to support the first forms of primitive life. In the giant seas that covered the planet, single-cell organisms began to make their appearance. Most of them were very simple single-cell bacteria that fed on chemicals in the ocean's waters. 
	Over time, a simple organism known as blue-green algae developed and spread across the seas. These algae were actually more like bacteria than like the algae which live in the oceans today. They were important to the future of the planet because they used sunlight and water to make food, and, in the process, created oxygen. As the blue-green algae thrived in the earth's seas, they began to fill the atmosphere with oxygen. Soon, the algae became so numerous that they formed huge reefs called strommatolites.
!Earth: The Once-Poisonous Planet
4 Billion BC

EARTH 
	For nearly 1.5 billion years after the formation of the earth, the planet was a seething, poisonous place filled with volcanoes and covered by dark clouds of water vapor and poisonous gas. There was no life anywhere on the planet. And the air, water and land as we know them today did not exist. 
	It took hundreds of millions of years just for the earth's molten surface to finally cool and harden. As it did, poisonous gases and water vapor were expelled from the earth's core, creating the first primitive atmosphere. No living thing could have breathed in that atmosphere since there was no oxygen and most of the gases in it were deadly. All around the planet there were erupting volcanoes and lakes of lava. 
	Over time, the earth's surface cooled enough so the water vapor in the atmosphere began to condense and turn into rain. Then for millions of years, it rained nearly continuously, filling up the depressions in the earth's surfaces with what are now our seas and oceans. 
	Eventually, the rain stopped and the clouds covering the earth thinned. For the first time in many millions of years, the sun shone through to the earth's surface. At around the same time, much of the poisonous gas in the atmosphere escaped into space, setting the stage for the development of the first life forms. 
SProtoceratops: Frilly Dinosaur
90 Million BC;6 Feet;400 Pounds

MONGOLIA, ASIA 
	Fighting the brutally hot winds of Mongolia's deserts, an American Museum of Natural History expedition in the early 1920s made a startling find. They unearthed masses of complete skulls and skeletons of Protoceratops, the first of the horned dinosaurs, known as protoceratopids. Living 90 million years ago, Protoceratops was the distant ancestor of the larger and more familiar Triceratops. They shared many of the same features. Measuring six feet long and weighing close to 400 pounds, Protoceratops had a large, heavy skull framed by a bony neck frill which was made lighter by two window-like openings in the skull. It also had a narrow, parrot-like beak with powerful, toothed jaws. 
	Protoceratops had no horns, although it had a crest, or nose-horn, along the top ridge of its snout. Some experts believe that this bump, only associated with the male of the species, was used in combat between enemies. 
	By far the most famous discovery made during this trip was a whole nest of very well-preserved Protoceratops eggs along with skeletons of hatchlings and juveniles. The eggs had been carefully laid out in a circular fashion in shallow depressions made in the sand, but the swirling sands had probably covered the nest so deeply that the babies never had a chance to hatch. 
	LOCALITY: Mongolia 
	LENGTH: 6 feet 
	WEIGHT: 400 pounds
Pteranodon: The Flying Reptile
70 Million BC;23 Feet;37 Pounds

GERMANY 
	Pteranodon belongs to an ancient group of flying reptiles called "pterosaurs" that lived at the same time as the dinosaurs. When the first pterosaur fossils were discovered in Germany in 1784, scientists thought they were aquatic animals. It took them 100 years to finally recognize they were flying reptiles! 
	Pteranodon had one of the largest wingspan of all the pterosaurs, measuring as much as 23 feet wide. This 37-pound creature had a sharp beak with no teeth, and almost half the length of its head was taken up by a bony, protruding crest whose purpose is still not fully understood. Some scientists think it may have been decorative and useful for attracting mates, while others believe that it may have acted like a rudder to steady Pteranodon during flight. 
	Pteranodon was not much of a flier. Instead it probably glided over the seas of what are now Kansas and Texas at speeds of up to 23 miles per hour, feeding on fish and mollusks. Because it had no teeth it probably caught fish like modern pelicans do, swallowing them whole. 
	LOCALITY: England; Germany; Midwestern North America 
	WINGSPAN: 23 feet 
	WEIGHT: 37 pounds
{The Largest Flying Reptile
100 Million BC;50 Feet;190 Pounds

	TEXAS, UNITED STATES 
	Until recently, the giant-winged Pteranodon was thought to have been the largest of the flying reptiles known as "pterosaurs." But in 1972 the remains of an even more enormous pterosaur was discovered in Big Bend National Park in Texas. 
	Quetzalcoatlus, or "feathered serpent" -- named after an Aztec god -- would have been the largest and heaviest flying reptile by far. The fossilized remains indicate that this giant pterosaur would have weighed nearly 190 pounds and had a wingspan of close to 50 feet, almost the same size as a small airplane! 
	Quetzalcoatlus was probably a glider and lived far inland, away from water. Like other pterosaurs, Quetzalcoatlus' wings were made of skin stretched along the lengths of greatly elongated fourth fingers of each claw. Its neck was probably longer than the earlier Rhamphorhynchus, and its head was probably more elongated. Scientists think Quetzalcoatlus had excellent vision and behaved like a modern vulture, spotting its prey from afar, then attacking or feeding on the carcasses of decaying dinosaurs. 
	LOCALITY: Texas, USA 
	WINGSPAN:50 feet 
	WEIGHT: 190 pounds 

\Rhamphorhynchus: Sea Skimmer
145 Million BC;3 Feet 3 Inches;Unknown

SOUTHERN GERMANY 
	With its long beak and outwardly pointing teeth, Rhamphorhynchus skimmed across the Late Jurassic seas snatching up fish for its nourishment. Small and agile, flying reptiles are among the best known of the group called "pterosaurs," which included Pterodactylus. 
	Like other pterosaurs, Rhamphorhynchus flew through the air on wings made of thin skin that was stretched along their bodies to the very tips of their extremely long fourth fingers, or "wing fingers." Well-preserved fossils of Rhamphorhynchus have been found in the limestone quarries of southern Germany which show the membranous skin of their wings and long kite-like tails which helped guide these creatures in flight. 
	It had a wingspan of about three feet three inches, and thin fibers running from the front to the back of the wings strengthened them greatly, much like the wing structure of the modern bat. Rhamphorhynchus' tail was also very long and strengthened by many thin, bony rods that ended in a small, flared out flap of skin resembling a kite. 
	LOCALITY: Germany; Tanzania, Africa 
	WINGSPAN: 3 feet, 3 inches
Death Ray for Dinosaurs?
65 Million BC

    One long-standing explanation for why dinosaurs died so mysteriously is that a star in a nearby constellation exploded and bathed the earth in deadly cosmic rays. If the star's explosion was close enough, then many animals, both large and small, would have been killed. 
	But there is one major problem with this theory. Why is it that some animals (such as birds, mammals, and crocodiles) survived while others (like dinosaurs, and marine reptiles) did not? 
The Hedgehog Dinosaur
152 Million BC;21 Feet;2 Tons
COLORADO, UNITED STATES 
	Though not always able to outrun its carnivorous foes, the 21-foot-long, two-ton Stegosaurus always had a final line of defense, its bony plated back and spiny tail. 
	If cornered or outmaneuvered by a larger enemy, the Stegosaurus' back plates afforded some protection while the four to eight spikes on the end of its tail (which grew as long as four feet) made it dangerous for any foe to approach too carelessly. 
	Paleontologists still don't agree about the placement of the vertical plates along the Stegosaurus' back, which you can see in this movie. The plates are not attached to bone, but were embedded in the dinosaur's back, which makes it difficult to tell if they were in a single row, double row or a combination of the two. 
	Many scientists believe the vertical plates may also have served as warming or cooling fins, picking up heat from the sun when the weather was cool to warm the Stegosaurus, or giving off heat when it was too hot. 
	Stegosaurus bones have been found in Colorado and Wyoming. They are believed to have lived primarily in the western part of North America. 
	LOCALITY: Colorado, Wyoming, USA 
	LENGTH: 21 feet 
	WEIGHT: 2 tons 

Stegosaurus: The Plant Eater
152 Million BC;21 Feet;2 Tons

COLORADO, UNITED STATES 
	Look how big you can grow if you eat your vegetables! 
	Stegosaurus had a small mouth with small teeth and apparently ate only small plants, but this peaceful dinosaur grew to 21 feet long and weighed up to two tons. 
	In addition to having small teeth, Stegosaurus also had a small brain. It may even have had the smallest brain in comparison to its body size of any dinosaur. Stegosaurus' brain was only about the size of a walnut. 
	The word "Stegosaurus" means "roofed reptile." It was named this because scientists originally thought the plates on its back lay flat to form a protective roof. 
	LOCALITY: Colorado, USA 
	LENGTH: 21 Feet 
	WEIGHT: 2 Tons
The Crash Helmet Dinosaur
82 Million BC;6 Feet;120 Pounds

ALBERTA, CANADA 
	Stegoceras was certainly not a dinosaur with which to butt heads. In fact, this dinosaur was built almost entirely for ramming its uniquely shaped head into other dinosaurs. 
	Stegoceras belonged to a family of dinosaurs known as "thick-headed reptiles," or pachycephalosaurs, because of their dome-shaped bony heads. Discovered in North America in the early part of this century, these plant-eating dinosaurs had high foreheads and massively dense skulls that were made up entirely of thickened bone. Scientists believe that Stegoceras used its giant "crash helmet" to butt the heads of other males of its group, a lot like the behavior of modern mountain goats. 
	Living in the Late Cretaceous Period, Stegoceras roamed the plains of North America, traveling in herds. Adults grew to about six feet in length and weighed close to 120 pounds. 
	LOCALITY: Alberta, Canada 
	LENGTH: 6 feet 
	WEIGHT: 120 pounds
MStyracosaurus: Spiked Reptile
80 Million BC;18 Feet;$6000

MONTANA, UNITED STATES 
	If you were a meat-eating dinosaur and had to stare a herd of Styracosaurus in the face, you might look elsewhere for your supper. 
	Like other plant-eating ceratopians, the 18-foot-long Styracosaurus had a massive, armor-plated head with heavy-duty spikes that would make any predator beware. While the better-known and larger Triceratops had a nose horn and two large eyebrow horns, Styracosaurus had a large nose horn and large sharp spikes around the upper edge of the armored frill that covered its neck. 
	Ceratopian fossils have been found in large beds in Montana and Alberta, in North America. In these beds all the skeletons are of the same variety and at different ages of life. This suggests they were members of a herd and were drowned during a flood. 
	If they were herd animals, perhaps they formed circles with their heads facing outward to ward off predators. Can you imagine a hungry meat-eater circling a herd, only to see sharp spikes and armor plate facing him at every point? 
	LOCALITY: Alberta, Canada; Montana, USA 
	LENGTH: 18 Feet 
	WEIGHT: 3 Tons
Dinosaurs Roam the Earth
250 Million BC

PANGAEA 
	Looking down on earth from space 200 million years ago, you would have seen a very different world. 
	Instead of the familiar continents, you would have seen one super-continent called Pangaea, and one gigantic ocean, and on the earth would be large ferns and conifer trees, many that would be strange to us today. 
	Most impressive, though, would be the dinosaurs. While some of these reptiles (whose name means "terrible lizard") were as small as a chicken, others were taller than a three-story building. 
	These great creatures appeared on earth about 225 million years ago and ruled until about 65 million years ago. 
	The first part of their reign was during the Triassic Period. During that time all the earth's land was in one continent, so the dinosaurs could spread freely across the earth. Also, the weather was warm and swamps covered much of the land. 
	During the next period, the Jurassic, the weather remained warm and plants and animals increased rapidly, but the continents had begun to drift apart. 
	The Cretaceous Period marked the end of the dinosaurs. The continents drifted further apart and the earth's climate became more varied. 
Removing Fossils: Easy Does It


    Finding a fossil is one thing. Removing it from the ground without damaging it is quite another. When most dinosaur fossil sites are discovered, only a fragment of the fossil is visible. The rest is usually embedded in hard earth or rock. Using very special tools and techniques, experienced fossil collectors can take weeks just to excavate the fossils out of a small patch of ground. 
	First, the area where the fossil has been discovered must be labeled, photographed and drawn so that records will be available for researchers to use in the future. Most of the time, the fossil bones are cracked or crumbly and need to be painted with shellac or glue to harden the fossil surface. Then they are usually covered with moistened paper until the fossils look like they are made of paper mache. If a fossil is small enough, excavators can scrape away the earth around the fragment and then carry it away. 
	Much larger fossils, such as the skull of a Triceratops or the thigh bone of an Apatosaurus, can require that huge pieces of rock surrounding the fossil be removed using power hammers and sometimes even explosives. When a large enough block has been carved out, the fossil can be carried away by tractor or truck. 
Tanzania: Finding the Big One
1909 AD

TENDAGURU HILL, TANZANIA 
	Buried deep beneath the ancient rock of southern Africa are the fossils of numerous varieties of dinosaur. 
	Between 1909 and 1912 two German paleontologists, Werner Janensch and Edwin Hennig, hired hundreds of untrained African natives to dig though the bone pits of what is now Tanzania. For three years, the workers labored in the sweltering heat, unearthing thousands of bones which they then crated and carried by foot to a distant port town on the east coast of Africa. 
	Among these bones, some of which weighed hundreds of pounds or more, the fossil hunters discovered the nearly complete skeleton of the giant dinosaur Brachiosaurus. When it was reconstructed at the East Berlin Natural History Museum in Germany, the skeleton stood 40 feet tall, as high as a three-story building, and the tallest complete dinosaur skeleton in the world. 
	Many other types of dinosaurs were found at the same site, including relatives of the spiny-plated Stegosaurus and giant plant eaters of North America. 
Ah, What Beautiful Teeth!
1822 AD

LEWES, ENGLAND 
	For thousands of years, dinosaur fossils turned up without anyone knowing exactly what they were. In the middle ages, some people even thought that dinosaur fossils were actually the bones of ancient dragons or giants. That all changed in 1822, when a quiet English doctor named Gideon Mantell became the first person to prove that a dinosaur fossil was actually from a race of prehistoric animals. 
	It began one day when Mantell and his wife Mary were calling on patients and happened to spot a pair of enormous fossilized teeth lying in a pile of gravel alongside the road. At first, Mantell couldn't figure out what animal, living or dead, could possibly have had teeth that large. So he traced the gravel to several nearby stone quarries and soon discovered more fossil fragments from the same animal. 
	When Mantell took the fossils to scientists, no one believed the teeth were from an ancient animal. But by looking closely at the kind of rock from which the fossils had come, Mantell could prove they were indeed very old. He also noticed that the fossils strongly resembled a modern-day lizard known as the Iguana. With this information Mantell wrote a paper claiming that the teeth were from an enormous 40-foot lizard named Iguanodon.
Making Tracks in Texas
145 Million BC

GLEN ROSE, TEXAS 
	Dinosaur trackways are some of the rarest and most informative fossil remains to be found. Fossil tracks were formed when dinosaurs walked over wet sand or soil and left an imprint which was quickly covered with sediment and thereby preserved. Most often this occurred along the sides of rivers or lakes where dinosaurs might have traveled. 
	By far the most famous dinosaur tracks were discovered in Texas at a place named the Glen Rose Formation. These fossil imprints show 23 overlapping trackways made by a large number of four-legged plant-eaters, most likely the giant Apatosaurus. There were trackways of both young and adult dinosaurs. At first, scientists thought the great number of tracks was proof that these dinosaurs traveled in large herds. But now scientists believe that the tracks were probably formed around the side of a lake where many large dinosaurs may have traveled at different times. 
	These tracks also helped disprove a common myth held about the way large four-legged dinosaurs like Apatosaurus known as sauropods carried their tails. Most believed that sauropods dragged their immense tails along the ground. But the Glen Rose tracks had no signs of tail marks, which meant that even giant sauropods held their tails aloft.
gTyrannosaurus: Fast or Slow?
67 Million BC;45 Feet;7 Tons
MIDWEST NORTH AMERICA 
	If you were to stand next to a Tyrannosaurus -- assuming he didn't eat you first -- you would barely come up to his knee. 
	Tyrannosaurus was the largest of the meat-eating dinosaurs, with a massive skull and teeth as long as seven inches. 
	Some scientists think the 45-foot-long, seven-ton monster you see in this movie was so big he could only waddle along slowly. 
	Reasoning from this, they believe he may have been a scavenger who chased other hunter-dinosaurs away from their lunch and ate it himself. Or perhaps he relied upon a surprise attack to bring down his prey. 
	However, other scientists who have examined the legs of Tyrannosaurus believe he was fast, capable of running along at up to 40 miles an hour. 
	LOCALITY: Montana, Texas, Montana, USA; Alberta, Saskatchewan, Canada; China; Mongolia 
	LENGTH: 45 feet 
	WEIGHT: 7 tons 
$Rhinoceros of Dinosaurs
70 Million BC;30 Feet;11 Tons

WYOMING, UNITED STATES 
	With its mighty three-horned head and heavily armored body, a fast-charging Triceratops must have been a fearsome sight to any hungry Tyrannosaurus. Certainly not what you would call an easy meal. 
	Triceratops was among the best known of the horned-face dinosaurs called "ceratopsids." It was also one of the last dinosaurs to exist on the planet before dinosaurs mysteriously became extinct. Scientists know this because Triceratops' bones have been found in the most recent sediments containing dinosaur fossils. 
	Normally a peaceful plant-eater, Triceratops offered the perfect defense against marauding predators like Tyrannosaurus. Massively built, an adult Triceratops could grow to more than 30 feet long and weigh up to 11 tons, heavier than an elephant! Its skull was built like an enormous shield with a thick neck frill, a short, thick nose horn and two long brow horns which sometimes measured over three feet long. 
	Triceratops lived some 70-65 million years ago and likely roamed in great herds throughout western North America. In 1900, dinosaur collector John Bell Hatcher recovered 32 ceratopian skulls in the area around Niobrara County, Wyoming, and almost all of them belonged to the Triceratops family. 
	LOCALITY: Wyoming, USA 
	LENGTH: 30 Feet 
	WEIGHT: 11 Tons 

_The Turtle: A Real Survivor
2 Million BC;8 Feet;4.5 Tons

INDIA 
	If you were to go back 200 million years, one group of animals would look almost exactly the same as it does today: the turtle. About the only difference you'd notice between modern turtles and prehistoric turtles is their size. Prehistoric turtles measured anywhere between six inches and 12 feet long. 
	Turtles are unique because they are the only reptiles that have most of their body enclosed in a shell. For the giant land turtles which lived at the time of the dinosaur, a sturdy shell was a must for use against meat-eating predators. The giant sea turtles alive at the time had fewer enemies so they could survive with a lighter shell, which enabled them to move quickly through the ancient seas. 
	Perhaps the most fascinating ancient turtle was Testudo Atlas, the world's largest land turtle. Alive in the Pleistocene epoch -- long after the dinosaurs disappeared -- Testudo weighed 4.5 tons, measured eight feet in length, and was also called "Colossochelys," which means "colossal shell." It had a sharp, toothless beak which it used to tear up plants. It supported its massive shell with four pillar-like legs that stuck out from either side of its body. If attacked, Testudo Atlas could retreat fully into its huge shell, where it was totally protected from even the fiercest of predators. 
	LOCALITY: India 
	LENGTH: 8 feet long 
	WEIGHT: 4.5 tons 

Tyrannosaurus: Not Always the Winner
67 Million BC;45 Feet;7 Tons
MIDWEST NORTH AMERICA 
	Tyrannosaurus rex means "king of the tyrant lizards," but being king didn't always mean winning a fight. 
	In this movie battle scene, we can see that a healthy triceratops -- with its sharp horns and armor-plated head and neck -- might well battle a hungry tyrannosaurus to a standstill. 
	LOCALITY: Montana, Texas, Montana, USA; Alberta, Saskatchewan, Canada; China; Mongolia 
	LENGTH: 45 feet 
	WEIGHT: 7 tons 

RTyrannosaurus the Tyrant
67 Million BC;45 Feet;7 Tons

MONTANA, UNITED STATES 
	One of the most ferocious of the dinosaurs was the terrible seven-ton meat-eating Tyrannosaurus, which literally means "king of the tyrant lizards." 
	Tyrannosaurus was probably the largest land predator ever. It stood almost 20 feet tall on its rear legs, had a massive tail, puny front legs, powerful jaws and sharp seven-inch-long saw-edged teeth for tearing its prey, such as plant-eating hadrosaurs. From nose to tail Tyrannosaurus measured up to 45 feet in length. Its skull alone was nearly four feet long. 
	These monstrous predators lived toward the very end of the age of dinosaurs and likely preyed on packs of duck-billed Hadrosaurs as well as herds of the better-defended Triceratops. According to fossil evidence, Tyrannosaurus ranged across great parts of North America and much of Asia. 
	Some paleontologists believe Tyrannosaurus was a scavenger, but most believe it was a terrible hunter, swift on its back feet and ferocious in battle. 
	LOCALITY: Montana, Texas, Montana, USA; Alberta, Saskatchewan, Canada; China; Mongolia 
	LENGTH: 45 feet 
	WEIGHT: 7 tons
Ultrasaurus: The Biggest Dinosaur?
138 Million BC;98 Feet;130 Tons

COLORADO, NORTH AMERICA 
	In 1979 the famed fossil hunter, James Jensen, made an amazing yet frustrating discovery. 
	While excavating a dinosaur site in western Colorado he unearthed one of the largest dinosaur legs ever known to man. Unfortunately, all he found was the leg. 
	Belonging to the same sauropod family as Brachiosaurus and Brontosaurus (also known as Apatosaurus), this giant plant-eater, now known as Ultrasaurus, could have measured up to 98 feet in length and weighed an enormous 130 tons, making it the largest land animal ever! Its front leg alone is about a third larger than that of Brachiosaurus. Some day we may find the rest of Ultrasaurus. 
	LOCALITY: Colorado, USA 
	LENGTH: 98 feet 
	WEIGHT: 130 tons 

