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
Created By Gina Wike Fossils A fossil is evidence such as remains, imprints or traces of once living organisms preserved in rock Fossils are found predominantly in sedimentary rock Fossils tell us when, where, & how organisms lived Fossils have helped scientists: 1. 2. 3. Determine when life began When plants & animals 1st lived on land When dinosaurs disappeared (other organisms also) How fossils form Body of an organism must be protected from scavengers & bacteria Body of organism must be covered by sediments (a quick burial) Needs to have hard parts such as bones & teeth Fossil Types Petrified Remains, Carbonaceous Film, Molds, Casts, Original Remains, Trace, & Index Petrified Remains Hard & rocklike Some or all remains have been replaced by another mineral Example: (bone) calcium is removed and replaced with quartz Carbonaceous Film most living organisms contain carbon sometimes carbon is the only thing left Coal is a fossil, but is more important as a fuel Molds A mold is a cavity in rock that is left behind when an organism decays Cast A cast is when a cavity is filled with sediments that harden into rock & take the shape of the original organism that decayed Original Remains Actual organism remains Amber (tree sap) preserves the organism Ice preserves an organism Trace Fossils Fossilized tracks & evidence of other animal activity Ex. Animal tracks & worm burrows Index Fossils Criteria to be an index fossil 1. Existed on Earth for a short period of time 2. Wide spread geographically 3. Abundant Determine the relative (how related) age of rock layers