Fossils

Footprint left by a dinosaur What are fossils? Fossils are the remains of a prehistoric animal or plant preserved in sedimentary rock. Types of fossils: Actual bones or remains Imprint or mold Cast (made when sediments fill in fossil) Track or trail Mold a cephalopod Remains of a trilobite Footprint left by a dinosaur

What are the odds? Poor Good Poor Good Tree growing in a swamp Horse drowned in a river flood plain Good Jellyfish in the ocean Poor Small animal caught in a tar pit Good

Studying Fossils Paleontology--The study of fossils before man. Geologic Time Scale--Rocks are placed in order from oldest to youngest.

Studying fossils cont’d Law of Superposition--Younger rocks lie on top of older rocks. Relative Age--Age of a rock when compared to other rocks. Geologic Column--Arrangement showing rock layers in the order they were formed.

Division of Time Era--The longest division of time. Period--Subdivision of an era. Epoch--Smallest division of time. The era divided in epochs is the Cenezoic Era.

Precambrian The Precambrain Era has the most primitive life forms. Earliest era Longest era Fewest fossils, all invertebrate species Only era with no periods or epochs Areas where Precambrain rock can be found Image sources: nasa.gov and nationalatlas.gov

Paleozoic The Paleozoic Era has the first vertebrates. Plant life began to develop on land First animals begin to appear on land Area where Paleozoic rock can be found Image sources: nasa.gov and nationalatlas.gov

Mesozioc The Mesozioc Era is considered era of middle life. Three periods: Jurassic, Triassic, and Cretaceous Era during which the dinosaurs lived Area where Mesozioc rock can be found Image sources: nasa.gov and nationalatlas.gov

Cenozoic The Cenozoic Era is the current era during which we live. Shortest era Era with the most fossils Area where cenozoic rock can be found Image sources: nasa.gov and nationalatlas.gov