2. GTS (update your ToC) Geologic Time Scale: a.How is the GTS organized? grouped by changes in global biotic turnover (many changes in flora/fauna species across the world in a relatively short time span) b. What are the units used to organize these events? Eon  Era  Period  Epoch c. Is the GTS “scaled” mathematically? Explain. No. New divisions are based on geologic and biotic changes on earth, NOT based on equal intervals of time. d. What appears to be the major emphasis on the GTS? changes in fauna in the very recent history (latest 1/2 Billion years)

3. GTS (cont) Geologic Time Scale: e. Why are new divisions in time made? climate change, appearance of fossils of new type of family, disappearance of many families or species/mass extinction events f. What patterns can you find? * Greater diversity closer to “today” * species appears, species disappear – “extinction happens” * flora and fauna start in the water and later show up on the land * life-forms generally become physically more sophisticated