Geologic Time Scale Use with Chapter 14, Section 14.1 RETEACHING SKILLS TRANSPARENCY MASTER 23 BIOLOGY: The Dynamics of Life Name Date Class Geologic Time Scale 1. What is the basis of the Geologic Time Scale? ~ The basis of the Geologic Time Scale was when the geological record was divided into time units that were related based on the mutual relation of the rock formations, mostly by the index fossils they contained. 2. Describe the divisions of the Geologic Time Scale. ~ 1. Precambrian Era 2. Paleozoic Era – Cambrian -Mississippian - Ordovician -Pennsylvanian - Silurian -Permian - Devonian 3. During what era and at approximately what date does fossil evidence suggest life had evolved on Earth? What form of life was this? ~ During the middle of the Precambrian Era in a period called the Archaean period fossil evidence suggests that life arose on Earth in the form of bacteria. 3. Mesozioc - Triassic - Jurassic - Cretaceous 4. Cenozoic - Tertiary - Quaternary 4. What forms of living things characterized the Cambrian period? ~ Invertebrates were the forms of living things that characterized that Cambrian period. 6. The dinosaurs and many other species became extinct in a relatively short period of time that marks what is called the K-T boundary, which stands between the Cretaceous and Tertiary periods. About how long ago did the dinosaurs become extinct? ~ The dinosaurs became extinct around 61 - 66 million years ago. 5. During what era did the first vertebrates evolve? What were these vertebrates? ~ During the Paleozoic Era the first vertebrates evolved and they were mainly algae dominant vertebrates. 7. Imagine you found a fossil of a bird that dates to 213 million years. Why would this find be astonishing to scientists? ~ Finding a fossil of a bird that dates back to 213 million years would be astonishing to scientists because that would be the Triassic period, the period before the first birds had evolved. 8. Suppose a geologist finds a layer of rock that can be dated to 320 million years ago. Layers from which periods would be expected to be above and below the newly discovered layer? ~ Layers of rock from the periods Pennsylvanian and Mississippian would be expected to be above and below the newly discovered layer.