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The preserved remains or traces of living things are called fossils The study of fossils is called paleontology The hollow space left when an animal's remains in hardened sediment dissolve is a mold The remains of something that lived during a short period of time and in many places around the world is an index fossil What is the first thing that happens during fossil formation? Rock layers form, an animal or a plant dies, a plant or an animal turns to stone, or sediments bury a plant or animal an animal or plant dies How are frozen mammoths similar to insects encased in amber? The entire organisms are preserved. If you were in a canyon with undisturbed rock layers, where would you find the oldest rocks? at the surface, at the bottom rock layer, in the top fossil layer, in the canyon's stream at the bottom rock layer If fossils of the same land animal are on different continents, what do you infer? the fossils formed in water, animal fossils look alike, the animals swam across the ocian, or the continents were once joined the continents were once joined What have paleontologists learned from studying plant fossils? The oldest plants lacked roots, stems, and leaves. What was Pangea? Earth's landmass millions of years ago What forms when dissolved minerals fill the space left by a mold? A cast Where are fossils most often found? in petrified wood, in ice, in sedimentary rock, or in the bottom layer of rock in sedimentary rock You're walking along and discover animal tracks that have burrowed and hardened in mud. The mud since has turned into rock and the animal track is now a fossil. What kind of a fossil is evidence of an animal's acitivity? Trace fossils are evidence of an animal's activity Why are most plant fossils carbon films? plants lack hard parts to fossilize, so only the details of roots, leaves, and stems are left behind What might be the result of an organism changing over time? becoming extinct, forming interesting fossils, surviving, or becoming larger or smaller surviving What is a cast? A layer where fossils are found, a fossil formed when minerals fill in a mold, a fossil formed by ice, or an imprint of a fossil a fossil formed when minerals fill in a mold What could you infer about the area where you find a Pecten fossil? the area was once formed by water How can you classify into tow groups a Pecten fossil, a fern fossil, a petrified tree, and a dinosaur footprint trace? You could classify these into plant and animal groups Why do you think paleontologists find fossils of small water plants, but few other plants, in the deepest rock layers? The oldest plants lived in the sea. Suppose you're on a dig at a deep canyon. How could you use index fossils to help you tell the ancient history of the canyon? You could notice where index fossils are found in the rock layers and then use the known ages of the index fossils to date the layers. On your dig, you find the shell of an ancient type of turtle that no one has seen before. What are possible ways to determine its age? Finding the age of the rock layer it was in, inferring its age from the age of index fossils in the same rock layer. Chapter 8 review and test preparation