2 ANY evidence of ancient life. So what exactly is a fossil?ANY evidence of ancient life.Body fossilteeth or bonesTrace fossilcast, track, burrowSo what exactly is a fossil?
3 What is a scientist who studies fossils called? paleontologists Next question…What is a scientist who studies fossils called?paleontologistsArchaeologists study the remains of ancient humans and their cultures.Write this down; it is an IMPORTANT distinction!Archae – beginning or ancientPaleo – old; the term was originally used by Charles Lyell 1838
4 FossilsIf the layers of sedimentary rock are the pages that tell the story of the Earth, fossils are the words.Literally, the word fossil means “dug up”.Technically speaking fossils are remains of life that are at least 15,000 years old.Preservation can include both altered and unaltered hard and soft parts. Fossils can also be casts and molds.Found in shales, sandstones, limestones, amber, ash, nodules, tar, and ice.The study of an organism from death to fossilization is called taphonomy (can include post-fossilization events as well).
6 Process of fossilization Fossilization depends on two critical steps:• rapid burial by sediment• mineralizationHelpful conditions:• anoxia (lack of oxygen following burial)• minimal disturbance subsequently• mineral-rich water in sediment
7 Types of Fossilization Unaltered RemainsOriginal material, including soft parts preservedRapid burial in ice, tar, or mummificationRecrystallizationOriginal material dissolvedNew mineral deposited simultaneouslyPermineralizationMinerals infill pores and holesMolds and castsInfilling with other materialOften, sedimentary infillCarbonizationPreservation as thin films of carbonOutline and sometimes detailed structures preservedPermineralization: Minerals dissolved in water fill in the open spaces in bone. This makes the bone harder and heavier, but some original bone material may be retained.
8 Unaltered Soft Parts (Amber) MosquitoScorpionFeather
9 Unaltered Soft Parts (Ice) “Blue Babe” bisonSiberian Wooly Mammoth
10 Unaltered Hard Parts: Tar and Anoxic Silt Beetle in tarLaBrea Tar PitAvitelmessus, NCFish from Messel, Germany
11 Unaltered Hard Parts (skeletal) SmilodonAshfall ParkColumbian Mammoth
20 Trace FossilsReflect the activity, or behavior, of organisms on land and in marine settings.Exogenic – on the surface.Endogenic – within the substrate.Shape of the trace fossil does not always mirror the animal.Trace fossils are named for their particular shape and form and not for the animal that made the trace.
21 Same animal may make several different types of trace fossils.