Unit 4: Plate Tectonics Fossils

I. Fossil Record Fossils form when: i. Living things die and are buried under sediment ii. As the sediment hardens and turns to sedimentary rock it preserves the shape of the organism iii. When the organism dies other living things eat the soft part of the animal or the soft part decays over time iv. The hard bones and structures of the organism are left behind to form a fossil

I. Fossil Record b. Types of Fossils i. Mold and Cast: 1. This is when a hollow area in sediment forms from an organism that was once there 2. Water brings in minerals and sediment that fills in the mold creating a cast (a solid copy of the shape of the organism) 3. Preserve the fine details

II. Fossil Record ii. Petrified Fossils: 1. Petrified means “Turned to Stone” 2. Minerals replace all or part of the organism 3. Water seeps into the space between the cells and when the water evaporates it leaves behind the minerals 4. Examples: wood, bones and teeth

I. Fossil Record iii. Carbon Films: 1. An extremely thin coating of carbon on a rock 2. This preserves delicate plants and insects 3. Many times these look like a drawing

II. Fossil Record iv. Trace Fossils: 1. Shows activity of ancient organisms 2. These prints get covered in sediment and turn to rock, leaving the imprint in the rock 3. Example: foot prints, trails and burrows

II. Fossil Record v. Preserved Remains: 1. Entire Organisms are preserved 2. Some get stuck in tree sap which becomes amber 3. Some are frozen in ice which can even preserve the hair of an animal

II. Geological Time Scale A paleontologist looks at fossils to date the earth . Split into Eras, Periods, and Years. Scientists split this into 3 separate eras i. Each era is split into multiple periods

II. Geological Time Scale d. 3 Different Era’s i. Paleozoic Era: life flourished and grew during this time period ii. Mesozoic Era: “Age of the Dinosaurs” iii. Cenozoic Era: Earth began to rebuild itself and the new environment began to form

II. Geological Time Scale e. Important time Periods i. Triassic Period (Mesozoic Era): Dinosaurs began to take over the earth ii. Cretaceous Period (Mesozoic Era): Large Extinction event that wiped out the dinosaurs iii. Paleogene Period (Cenozoic Era): earth began to cool and the climate changed allowing for new and different growth.