May 19, 2010 What was the purpose of the timeline activity? What is the name of the era we are living in today?

Evidence Supporting Evolution FOSSILS any preserved evidence of an organism Estimated that 99% of species that have ever lived are extinct! Mostly formed in sedimentary rock Fossilization How a fossil is made

Activity Cut out the “fossils” and put them together to determine what organism it was!

Diprotodon Giant wombat or Rhinoceros wombat Largest marsupial ever to live 1.6 mil – 45,000 ya

How do we date fossils? Law of Superposition Newer fossils are found relatively close to the surface while older fossils are found deeper underground. (relative dating)

How do scientists date CARBON? How do we date fossils? Radiometric Dating Uses the half life decay of radioactive material to determine age. (actual dates) How do scientists date CARBON?

Trace Fossil Indirect evidence left behind Footprints Burrows Animal waste

Dinosaur Ridge Morrison, Colorado http://www.dinoridge.org/

Molds and Casts Organisms buried in sediment may decay or dissolve away leaving a mold. If the space fills with sediment, an external cast can be made. Molds and casts are three dimensional and preserve the surface contours of the organism.

Replacement Original organism material is replaced by minerals Can leave replicas of hard tissue (shells, bones, etc) or soft tissue (muscle, fat, etc)

Petrified Empty spaces are filled with minerals

Amber Tree sap hardens into amber Preserves specimen

Original Material Mummified/frozen organisms

Who studies fossils? Paleontologists Reconstruction of Ichthyosaurus.

rock formed by the growth of blue-green algae or cyanobacteria stromatilite Trace fossil rock formed by the growth of blue-green algae or cyanobacteria http://www.youtube.com/watch?v=4opsN_iQdEs

ammonites Replacement/Mold and Cast 415 million years ago

Today’s organisms believed to be derived from ammonites