Yuen Li., age i5, of Victoria, B. C:, Canada, for her question:
What happened in the Jurassic Period?
The Jurassic Period of earth's history came to an end about 130 million Years ago. If we could go back, Just to Peek, We would think that our earth was an alien planet. Most of the plants and all of the animals would be strangers to us. Even the mountains and shorelines of our old planet Were different.
The long eras of earth's history are like diaries. The name of each era suggests a step forward in the story of life. The Mesozoic era, meaning middle life, recounts the progress from the ancient life in the sea to the conquest of life on the land. Its 110 million Years are divided into three periods. The Jurassic Period unfolded through the middle years of the Mesozoic era.
Many geological Periods are named for places where their secrets were revealed. Rocks and fossils of the Jurassic Period were unearthed in the Jura mountains between France and Switzerland. Around the world, rocks of the Jurassic Period reveal the bones of 80 to 100 foot lizards that must have Weighed 20 to 40 tons. For this was the age of the dinosaurs.
The Jurassic Period opened 155 million years ago and lasted through Some 25 million years. The arid climate ranged from scorching heat to frigid cold. The Appalachians had grown to their full height, but North and South America Were separated by 8 shallow sea. At one time the Sea invaded Our Western coast and then receded. There were no Rocky Mountains, but the Jurassic Period saw the formation of the Sierra Nevadas.
The sea floors were littered with ammonoids hiding in their coiled shells. Fishes and giant reptiles thronged the waters. Amphibians, large and small, wallowed in the swamps. The ferny coal forests had given way to pines and palmy cycads, but there Were no leafy oaks and no flowers.
The land was dominated by dinosaurs of all shapes and sizes. One variety spread giant bat wings and took the first flight above the face of the earth. And unnoticed by the lumbering lizards, other little animals were learning to cope with the world. These timid heroes Were the remote ancestors of our modern mammals.
The shape of the earth and life in the Jurassic Period would seem strange to us. But the seeds of our modern world were there and starting to sprout. In the next chapter, the dinosaurs declined while the mammals advanced to take over the world. The descendants of the flying feathered reptiles becavie the birds, and. Soon the plant world put forth its first tender flower.