The Dinosaur Age

fossil bones embedded in rock. They remove some of the overlying rock and dirt so they can examine what they've found. They decide important enough to take to the museum laboratory. First they clear the area being careful not to disturb the fossil remains. Now they begin the job of uncovering the fossil bones. They must work very carefully. The dirt is removed a little at a time to reduce the danger of damaging the find. Soon they are able to identify their find. It's the paddle or flipper of a plesiosaur. A plesiosaur was a large water living reptile or sea serpent closely related to the dinosaurs. from the age of the rock in which it was found. They know that this plesiosaur lived perhaps a 100 million years ago. When one side of the paddle has been cleared of dirt and rock, the other side must be cut away so that the entire rock slab with the bones in place can be lifted out. The slab will be covered with a plaster cast so the bones can be moved without crumbling or breaking them. First, pieces of wet newspaper cover the bones in order to protect them from the plaster. Then plaster of Paris is added to the water. Pieces of burlap are soaked in the plaster of Paris and carefully laid bones. The length of the cast to prevent her hardens. The plesiosaur paddle with every bone in place is carried back to the museum. At the museum, the paleontologists work in their laboratory on the job of preparing the fossil materials for study or exhibition. Carefully the cast is cut away. Great skill and patience are needed. The paper is lifted off. The bones must be freed from the dirt and rock that still remains. When the bones are clean enough, a do of paint is placed on each one. Then they are numbered. The paint on the numbers will make it easier for the paleontologist to put the bones together in their proper order after they are lifted from the plaster cast. Finally, when enough fossil bones of a theosaur have been gathered together, an entire skeleton is assembled. The new paddle is put in its proper place. Skeleton is mounted on iron supports to hold it in a natural position. The bones of many animals collected over many years have been used to make this skeleton. The shape of the bones and the position in which they may have been found helped the paleontologist in his job. The plesiosaur skeleton has been put together as it must have been when the animal was alive. Sometimes the museum may decide that a model of the animal is needed. A specially trained artist is called in. The artist works with the paleontologist to make a sketch of the plesiosaur skeleton. From his sketch, he makes a detailed and accurate drawing of the animal as it may have looked. And from the artist's drawing, a model is finally completed. Same way models of other long deadad animals like this brontosaurus are made. Finally, visitors to a museum may look at an exhibit like this one. This brontosaurus was a dinosaur, probably the largest of all dinosaurs. A model of a man built to scale will give you some idea of its size. No man, of course, lived when the dinosaurs were alive. Brontosaurus was a planteater. Some brontosaurs weighed as much as 50 tons, perhaps 10 times as much as a modern elephant, and may have been 60 to 70 ft long. The name Brontosaurus means thunder lizard. It gets its name from the fact that when it walked, it probably shook the earth, making a noise like thunder. This is Stegosaurus, one of the smaller dinosaurs, only 8 ft high and 15 ft long. Again, the model man will give you an idea of its size. Stegosaurus too was a planteater, and the strange armor along its back was probably part of its defense against attack by the larger, more powerful, flesheating dinosaurs. Its spiked tail could have been a handy weapon, too. Trackodon is called the duck bill dinosaur. It measured almost 30 feet from its head to its tail. Notice the scale model man again. Crackodon walked upright. It lived in the rivers and swamps of North America feeding upon water plants. The peculiar shape of its mouth gives it the name duck bill. Paleontologists believe it may have strained its food from the mud much as a modern duck does. This is Tyrannosaurus. The scale model man shows you its great size. Fortunately, perhaps, the last Tyrannosaurus died about a 100 million years before the first man appeared. For Tyrannosaurus was the tyrant lizard, the most terrible of all the dinosaurs. Its skull measured more than 4 feet in length. Its sharp pointed 6-in teeth prove it was a meat eater. Few animals probably could defend themselves against its attack. The fossil bones of dinosaurs and other giant reptiles have been found on every continent. From fossils like these, we know that dinosaurs ruled the earth for over 100 million years only to disappear completely. No one really knows why. The dinosaurs and the other giant reptiles are gone. But today, paleontologists and other scientists are continually searching for fossils in order to better understand the record of life on Earth. [Music] [Laughter] [Music]