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
Evolution (Fossils/Geologic Time) Review PO4 – Describe how rock and fossil record show that environmental conditions changed over geologic and recent time. Geologic time = the summary of earth’s history, divided into intervals of time defined by major events or changes on Earth; measured in thousands, millions, and billions of years PO5 – Describe the conditions necessary for fossils to form. The organism or trace of the organism must be preserved before it decomposes or disappears so it must be covered or buried in sediment rather quickly and then as the layers of sediment harden together over time creating sedimentary rock PO6 – Distinguish among the different types of fossils. Fossil = a trace or the remains of a once-living thing from long ago Index fossil = a fossil of an organism that was common, lived in many areas, and existed only during a certain span of time; used to determine the age of rock layers Trace fossil = evidence of an animal’s presence in a given location such as footprints, trails, holes, and feces Body fossil = a fossil of an actual body part such as teeth or bones Cast fossil = a solid model in the shape of an organism made when a mold becomes filled with minerals Mold fossil = a visible shape left after an animal or plant was buried in sediment and then decayed away PO7 – Name some common types of organisms from each era of geologic time. Paleozoic = means ‘ancient life’; fish, reptiles, insects, ferns Mesozoic = means ‘middle life’; dinosaurs, mammals, birds, flowering plants Cenozoic = means ‘recent life’; called the Age of Mammals because mammals became a main category of life on Earth PO8 – Explain why Precambrian Era has a poor fossil record. Precambrian time = the Hadean, Archaen, and Proterozoic eons together and make up almost 90% of Earth’s history Very few plants or animals existed and most that did were single-celled and microscopic; many had soft bodies that rarely form fossils; the planet was dominated by volcanoes (igneous rock) which never contain fossils; fossils form in sedimentary rock PO9 – Explain how scientists determine the age of fossils. Relative Age = the age of an event or object in relation to other events or objects Absolute Age = the actual age of an event or object Radioactive or radiometric dating = a technique used to date materials such as rocks comparing amounts of radioactive isotopes and decay products using known decay rates Half life = the length of time it takes for half of the atoms in a sample of radioactive element to change from an unstable form into another form Other Vocabulary Evolution = the process through which species change over time Extinction = the permanent disappearance of a species Mass Extinction = one of several periods in Earth’s history when large numbers of species became extinct at nearly the same time Natural selection = the process through which members of a species that are best suited to their environment survive and reproduce at a higher rate than other members of the species Adaptation = a characteristic, a behavior, or any inherited trait that makes a species able to survive and reproduce in a particular environment Eon = the largest unit of geologic time; Earth’s history is divided into 4 eons (Hadean, Archean, Protozoic, Phanerozoic) Era = Eons are divided into Eras such as the Phanerozoic Eon is divided into the Paleozoic, Mesozoic, and Cenozoic Eras Period = each Era is subdivided into a number of Periods such as the Mesozoic Era is divided into the Triassic, Jurassic, and Cretaceous periods Epoch = the periods of the Cenozoic Era are divided into Epochs