Ch. 6.1 Fossils & Geologic Time
- 1. Ch. 6.1 – Fossil Evidence of Evolution
- 2. • How do scientists know what organisms looked like if they don’t exist anymore? 1. How do fossils form? • Fossils – remains or traces of prehistoric life • Fossil record – complete record of all fossils discovered • Helps us understand how life forms have changed over time.
- 3. Carbonization Amber Petrified wood Mineralization (petrified): “turned into stone” Altered remains: direct evidence Amber: hardened resin (sap) of ancient trees; preserves delicate insects Carbonization: effective in preserving leaves & delicate animal forms (carbon film left behind) Molds: impression of an organism in a rock Cast: fossil copy of an organism in a rock Mold & Cast
- 4. Which refers to the impression of an organism found in a rock? A. Cast B. Fossil C. Mold D. Trace fossil Cast Fossil M old Trace fossil 0 000 45
- 5. Which refers to a fossil that is turned into stone? A. Carbonization B. Mineralization C. Mold D. Trace fossil Carbonization M ineralization M old Trace fossil 0 000 45
- 6. Animal footprints Copralite (dung & stomach contents) Animal burrows (worm burrow) Gastrolith (polished stomach contents) Altered remains: indirect evidence Trace fossils: preserved evidence of the activity of an organism
- 7. • Original Materials: original tissues are preserved – Most common with teeth, bones, and shells – Extremely rare to find remains of an entire animal – Example: Fully preserved, frozen mammoth found in Siberia (Lyuba) 1. How do fossils form?Baby woolly mammoth: 4 ft. long between 10,000 & 40,000 yrs old
- 8. Which is the preserved evidence of the activity of an organism? A. Cast B. Fossil C. Mold D. Trace fossil Cast Fossil M old Trace fossil 0 000 45
- 9. • Instead of dating fossils directly, scientists date the rocks the fossils are embedded inside. • Revisiting the rock cycle: 2. How is geologic evidence used to help determine the age of fossils?
- 10. Which kind of rocks are most fossils found in? A. Igneous rocks B. Sedimentary rocks C. Metamorphic rocks Igneousrocks Sedim entaryrocks M etam orphicrocks 0 00 45
- 11. • The geologic time scale is a chart that divides Earth’s 4.6 billion year history into different time units. 1. Eons 2. Eras 3. Periods 4. Epochs 2. How is geologic evidence used to help determine the age of fossils? longest shortest
- 12. Which era and period are we currently in? A. Mesozoic and Neogene B. Precambrian and Hadean C. Cenozoic and Paleogene D. Cenozoic and Quaternary M esozoicand Neogene Precam brian and Hadean Cenozoicand Paleogene Cenozoicand Quaternary 0 000 45
- 13. • Scientists now understand that sudden disappearance in fossils in rock layers are evidence of extinction events. • Extinction occurs when the last individual organism of a species dies. • A mass extinction occurs when many species become extinct within a few million years or less. • Extinctions occur when environments change (either gradually or suddenly). 3. What causes species to change over time?
- 14. Evidence of the meteorite impact (65 mya)
- 15. The fossil record contains evidence that five mass extinction events have occurred during the Phanerozoic eon. 3. What causes species to change over time?
- 16. How many major extinction events have occurred in Earth’s history? A. 2 B. 3 C. 4 D. 5 2 3 4 5 0 000 45
- 17. • As fossils were discovered, patterns emerged that showed many different species with similar body structures. • Evidence suggests that species change over time. • Change over time = Evolution (to evolve) • Biological evolution is the change over time in populations of related organisms. 3. What causes species to change over time?
- 18. • The fossil record is evidence that horses descended from organisms for which only fossils exist today. • There are many other examples of this that we will learn about.
Editor's Notes
- #17: http://commonfossilsofoklahoma.snomnh.ou.edu/geological-time-scale