Fossils

What are fossils? The remains, imprints or traces of an organism that lived long ago. Preserved in rock. Typically sedimentary rock Must be buried quickly Types of fossils: Molds Casts Carbonaceous film Petrified remains Original remains Trace fossils Hard parts decay leaving behind a cavity in the rock Formed when the mold becomes filled Thin film of carbon forms outline on rock Minerals replace the original organism The actual organism is preserved Evidence of organism activity (footprint)

How were entire organisms preserved? Original remains can be preserved in different materials. Ice Tar Amber Glaciers La Brea Tar Pits Tree sap

Otzi the Iceman Called Otzi, because found in the Otzzi Alps near Hauslabjoch on the border between Austria and Italy Look at how, when and why A frozen organism does not decay because most bacteria can’t survive freezing temperatures.

Oldest human found Omo Pics of Skulls

Different types of fossils Mummification-Fossilized remains of an organism found in very dry places Gastrolith-Fossilized stone from the digestive system of a dinosaur (stomach stone)

Diff types of Fossils Coprolite-fossilized dung or waste Petrification-Minerals replace organic material Imprint-carbonized impressions of plants and fish

Index Fossils Organisms that lived during short spans of geologic time Found in rock layers in different areas of the world. This indicates that rock layers formed during the same period of time.

What are fossil fuels? Raw fuel that comes from the remains of once living organisms Solid Liquid Gas Coal Petroleum or Oil Natural Gas or methane

Why do scientists study fossils? Clues to the past Global changes & regional changes Environmental Natural disasters Climate change Geologic Evolution

How can relative age of rocks be determined? Using the law of superposition relative age can be determined Relative age is comparing one objects age to another. If there are three layers Top is youngest Then middle Bottom is oldest Index fossil is always found in a particular layer

How is absolute age determined? The specific age of a rock or fossil Uses radioactive decay Half-life is the amount of time it takes for ½ of the mass of an element to decay into, more stable, element. The rate of decay can be measured Particular elements have a constant rate of decay Carbon-14 dating for living things Not always 100% accurate! Half-life

Review of geologic time scale. Precambrian Paleozoic Mesozoic Cenozoic Era Periods Epochs Cambrian Ordovician Silurian Devonian Carboniferous Permian Triassic Jurassic Cretaceous Tertiary Quaternary Paleocene Eocene Oligocene Miocene Pliocene Pleistocene Recent

What is a fossil??? Play palentologists studying fossils Play palenotologists studying tracks and traces

The End!