Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
7.3.c Students know how independent lines of evidence from geology, fossils, and comparative anatomy provide the bases for the theory of evolution. 7.4.e Students know fossils provide evidence of how life and environmental conditions have changed. Key Concept: Similar body structures, patterns of early development, molecular structures, and fossils all provide evidence that organisms have changed over time. Comparative anatomy- the comparison of the structures of different organisms Similarities in body structure: Homologous structures: similar structures that related species have inherited from a common ancestor All probably inherited similar structure from early ancestor they all share Orange bones are homologous structures Similarities in early development: Some species look similar in early stages of life Share a common ancestor Similarities in DNA and proteins: If two species have similar DNA and proteins, probably evolved from same ancestor Most fossils form: Organisms that die become buried in sediments Sediments = particles of soil or rock Bird Fossil Most common fossils are molds and casts Mold- a hollow area in sediment in the shape of an organism or part of an organism Cast- solid copy of the shape of an organism Petrified fossil- fossils which minerals replace all or part of an organism Sediments cover organism, water rich in dissolved minerals soak into spaces, over time minerals come out of the solution and harden Trace fossil- provide evidence of ancient organisms Foot prints are an example of a trace fossil Sediment buries footprint, sediment becomes rock, and preserves footprint Preserve the remains with little or no change Types of preserved remains- tar, amber, and ice Tar- tar soaked into bones preserving bones from decay Amber- trapped on sticky resin, resin covers organism, sealing it from the air, protecting it from decay Ice- freezing has preserved hair and skin too Paleontologistsscientists who study fossils Key concept: The fossil record provides evidence about the life and past environments on Earth. In addition, scientists use fossils to study the rate at which evolution has occurred. Oldest rock layers contain the oldest fossils Oldest fossils are of simple organisms like bacteria Fossils found in the area also gives paleontologists an idea of what the environment looked like Fossils show how environment has changed Gradualism- is a hypothesis that proposes that evolution occurs slowly but steadily Punctuated equilibria- is a hypothesis that accounts for the gaps in the fossil record, species evolve quickly during relatively short periodsperiods of rapid change are separated by long periods of little or no change Most scientists think that evolution can occur gradually at some times and more rapidly at others Scientists use evidence from: Fossils Body structures Early development DNA and protein structures to determine the evolutionary relationship among species