DO NOW Pick up the green sheet and the pink sheet. Get out your notebook.

WHAT TO KEEP KEEP: Syllabus Lab Safety Sheet Purple Sheet Put pink sheet and green sheet with the purple sheet in the front of your notebook. Pull everything else out! We will come by with a recycling bin.

REVIEW Magma cools. Rock weathers and erodes. Lithification (compaction and cementation) Heat and pressure changes the rock. Rock melts to become magma.

FOSSIL RECORD SES4: Students will understand how rock relationships and fossils are used to reconstruct the earth’s past.

WHAT ARE FOSSILS? Remains of an ancient organism or its activity. Require rapid burial after death. Quick sedimentation. Often due to water. Best locations – bottom of lake or ocean. Sediments compact and build up over time.

WHY STUDY FOSSILS? Fossils: Help determine the absolute and relative ages of rocks. Provide clues to past geologic events, climates, and evolution of living things. Are an indicator of an area's ancient environmental conditions and climates.

FOSSILS FOUND IN SEDIMENTARY ROCKS Sedimentary rock forms in layers. Sedimentary rocks formed by: 1. Weathering ✔ 2. Erosion ✔ 3. Deposition ✔ 4. Lithification ✔ Compaction and Cementation

FOSSILS FOUND IN SEDIMENTARY ROCKS Igneous rocks are too hot. Metamorphic rocks require too much heat and pressure to have fossils.

BEST CONDITIONS FOR FOSSILS TO FORM Quick burial in moist sediments - prevents scavengers and bacteria from destroying. Quick burial in volcanic ash. Presence of hard body or plant parts – teeth, bones, shell - soft parts decompose quickly. Consistent temperatures.

BEST CONDITIONS FOR FOSSILS TO FORM Lots of minerals in ground water – minerals slowly replace body. Very fine sediments. Calm conditions, so that remains are not broken up (ex: waves, wind.).

FOSSILS PROVIDE CLUES TO THE PAST What living things existed in the past. How living organisms have changed over time. What ecosystems and environments were like. What can you conclude about past environments in places where fish fossils are found?

FOSSIL DATING Absolute age Radiometric dating (remember Penny Lab and half life?) Radioactive isotopes – carbon, nitrogen, uranium Tells how many millions of years old something is.

FOSSIL DATING Relative dating Location of fossils in layers of rock. Oldest layers are below newer layers. Tells which are older or younger without specific dates.

FOSSILIZATION: MINERALIZATION This is creating a fossil using minerals to replace the hard tissue. More common type of fossil. Soft body parts quickly decay – harder tissues take longer. Mineralized water fills the pores of the organic tissues and moves through the cellular spaces. Water evaporates. Excess minerals replace tissues over time.

FOSSILIZATION: OTHER METHODS Other ways to Fossilize: Mummification: Drying Amber: Tree sap Tar Seeps: Petroleum ooze NOTE: Fossilization is Rare! Most organisms decay first!

FOSSILIZATION: OTHER METHODS Other ways to Fossilize: Freezing: Ice Carbonization: Carbon print remains Chemicalization: ex: Peat bog

TYPES OF FOSSILS: CASTS AND MOLDS Do not contain actual remains. Are impressions of physical characteristics. Organism dies and buried in sediment creating imprint. Mold: Imprint left by tissues - most often bones, shells, and hard parts. Cast: Minerals fill in mold and take shape of original organism.

TYPES OF FOSSILS: IMPRINTS Shallow external molds or voids left by animal or plant tissue Formed from compression of tissues. Can include carbonization – dark organic residue. Carbon imprints can show surface features.

TYPES OF FOSSILS: COPROLITES Fossilized dung. Rare due to rapid decay. More common for fish and reptiles. Can provide information about organism's diet.

TYPES OF FOSSILS: GASTROLITHS Digestive (gizzard) stones. Usually reptiles. Provide clues to feeding habits.

TYPES OF FOSSILS: TRACE FOSSILS Evidence of life, includes: Tracks Trails Footprints Burrows Borings Ichnology: the study of the behavior of extinct organisms by studying trace fossils.

FINDING FOSSILS The right kind of rock: Sedimentary The right age rock: Most multicellular life appeared less than 500 million years ago. Different organisms appear in different time periods.

FINDING FOSSILS The right environment for preservation: Example: ancient seas

FOSSIL RECONSTRUCTION Difficulty dependent on how much remains. Clues from: Position of the remains. Best-fit calculations. Structural considerations. Similarities in known and modern organisms.

REVIEW Fossils tell us a lot about: Recent human history What the Earth is made of Past environments Origin of Earth’s oceans REVIEW #1 due tomorrow

LAB: FOSSIL RECONSTRUCTION In this lab, you will construct a skeleton of a mystery fossil from the Jurassic Period and make inferences about what the animal looked like, what food it ate, and its environment.

LAB: FOSSIL RECONSTRUCTION Neatly cut out the pieces. Piece them together at your lab desk. Follow directions on the lab sheet. Once you are satisfied, you will glue it down on the colored piece of paper.

LAB: FOSSIL RECONSTRUCTION Once you have glued it down, answer the questions on the lab sheet. One person in the group turns in the reconstruction. Make sure your lab partners are listed on your lab sheet.