Evolution Evolution : The Science behind the theory Evolution Evolution : The Science behind the theory Geological time Fossils Darwin & Natural Selection Species changing over time Anatomical & Embryological evidence Speciation

Summary of Evolution of Life Formation of the earth’s early crust and atmosphere Small organic molecules form in the seas Large organic molecules (biopolymers) form in the seas First protocells form in the seas Single-cell prokaryotes form in the seas Single-cell eukaryotes form in the seas Variety of multicellular organisms form, first in the seas and later on land Chemical Evolution (1 billion years) Biological Evolution (3.7 billion years)

Fossils How do we know about the past? How do we know about the past?

What is a fossil? A fossil is an impression, cast, original material or track of any animal or plant that is preserved in rock after the original organic material is transformed or removed.

A fossil may be:  an original skeleton or shell;  a mold or cast;  traces such as footprints or worm tubes Material that has replaced the once living thing

Types of Fossils Body fossils – actual parts of an organism bones, shells, leaf imprints

Trace fossils – evidence of life having been there tracks, burrows, casts Types of Fossils

Trace Fossils Mold – reproduction of the inside or outside surface of a living thing Cast – duplicate of the original organism; usually formed by replacement of inside of living thing

Burrows or borings – Spaces dug out by living things & preserved as is or filled in Trace Fossils Tracks – impressions of passage of living things

Trace Fossils Imprint – Thin objects such as a leaf that falls onto sediment & leaves an imprint then the sediment hardens into rock

Minerals penetrate & replace the hard parts of an organism producing a copy of them Amber & Ice An entire organism was quickly trapped in ice or tree sap that hardens into amber Petrified Fossils

Where are fossils found? Sedimentary Rock Sedimentary Rock

Why sedimentary rock?

Hard body parts such as skeletal bones or exoskeletons What conditions promote fossilization? Rapid burial and/or lack of Oxygen

Unaltered - insects or plant parts trapped in amber or ice ; original unaltered material from the living organism Replacement – the hard parts of an organism dissolve and are replaced by other minerals Petrification – rock-like minerals seep in slowly and replace the original organic tissues Authigenic - molds or casts of organisms tissue material is decomposed or of markings left behind by an orgasnism

Putting it all together Examples of Fossils...

Sporadoceras Nautilus

Orthoceras Squid

Trilobites Lobster

Fossil Fish

Dinosaur Bones