Presentation on theme: "Fossilization and Fossils. So what exactly is a fossil? ANY evidence of ancient life. Body fossil teeth or bones Trace fossil cast, track, burrow."— Presentation transcript:
Fossilization and Fossils
So what exactly is a fossil? ANY evidence of ancient life. Body fossil teeth or bones Trace fossil cast, track, burrow
What is a scientist who studies fossils called? paleontologists Archaeologists study the remains of ancient humans and their cultures. Write this down; it is an IMPORTANT distinction! Next question…
Fossils If 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).
Process of fossilization
Fossilization depends on two critical steps: rapid burial by sediment mineralization Helpful conditions: anoxia (lack of oxygen following burial) minimal disturbance subsequently mineral-rich water in sediment
Types of Fossilization Unaltered Remains Original material, including soft parts preserved Rapid burial in ice, tar, or mummification Recrystallization Original material dissolved New mineral deposited simultaneously Permineralization Minerals infill pores and holes Molds and casts Infilling with other material Often, sedimentary infill Carbonization Preservation as thin films of carbon Outline and sometimes detailed structures preserved
Unaltered Soft Parts (Amber) Scorpion Mosquito Feather
Trace Fossils Reflect 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.
Same animal may make several different types of trace fossils.
Trilobite resting trace
Other trace fossils include trackways on land (mostly dinosaur, reptile, and amphibian) and coprolites (fossilized feces, “ poop ” ).