Fossils - Oct. 18, 2022 Flashcards
Fossil Definition
Mineralized remains Body Fossils (ex. bones, shells, teeth, leaves) or Trace Fossils (ex. Burrows, tracks, impressions) of deceased life forms
Taphonomy Definition
The study of the conditions under which plants, animals, and other organisms change after death and are sometimes conserved as fossils
Silt Definition
Fine nutrient rich soil; found by water
Sediment Definition
Matter that settles to the bottom of a liquid (like dirt)
Imprint Definition
A rock cast of an original organism imprints can show soft tissue
Soft Tissue Definition
Our hair, muscles, skin, and tissue that is soft not hard like bone.
Preserve Defintion
When parts of an organism are saved with the skeleton
Ice preserves animal remains the best
Relative Age Dating
Dating a fossil or material using surrounding features; for ex. getting one fossils then allows you to know the fossils above are younger and the ones below are older (Law of Superposition)
Law of Superposition
Any fossil above one is younger and any below it are older
Index Fossil
They are used to find the relative age of a fossil; ex. the fossils above it are younger than the ones below it. Many species are used as index fossils since they went through massive evolutionary changes.
Strata
Layers of rock laid down by wind and water over the course of Earth’s 4.6 billion-year history
Radiometric Dating
What we use to get the exact age of a fossil
Uranium 238 is used to date rocks
Carbon 14 is used for living things
Isotope
An isotope is one of two or more species of atoms of a chemical element with the same atomic number and location in the periodic table and closely the exact same chemical habits but with unalike atomic masses and physical attributes.
Half-life
After a certain period of time called a Half-life half of the nuclei decay’s
Example - There is 40 grams of a substance and the half-life is 20 years, how much will be left after 60 years?
40 grams - 0 years
20 grams - 20 years
10 grams - 40 years
5 grams - 60 years
Chronometric
In contrast, chronometric dates place events in their chronological position with reference to a universal time scale such as a calendar.
Fossil Complexity
The different complex stages of an animal. How to tell whether it’s the same animal or an adaptation as well as how long ago it lived. What it did or ate to discover whether it was a carnivore or not.
What are the perfect conditions for fossil formation? How do fossils form?
You need to not die a violent death and preferably be by a body of water, ice, or a dry area like a desert. You also need to be covered in sediment quickly. Fossils form underground when minerals start to replace cells and atoms in bones and become stone.
Perfect Conditions for a Fossil
Fast Burial, Hard Parts
Organisms should die alone of natural causes
Should die in or near water
Sediment covers the body layer by layer
Minerals get deposited into air pockets of the bones
Minerals replace the calcium in the bones
Fossils eventually come to the surface
What are the ways we get preserved animal remains? Which is the best and why?
There are four ways to get animal remains. There is another which I will start with but it isn’t really animal remains. This method is a cast or mold method where you make a mold from what a fossil would look like and make a cast from it. Another method is Permineralization aka Petrification; when the organic components of bone break down (ex. blood cells and fat) or inorganic components, made from minerals, remain which leaves a bone-shaped mineral form with pores throughout it. A third method is Complete Preservation, when an organism dies and is covered with, tree sap (later turned into amber), water, or tar (liquid asphalt). Mummification is another; this is where a skeleton or any remains become dehydrated and the bacteria cannot colonize. The last one is compression where an organism made a mark of high pressure on the rock. The best one would be ice as it preserves the skeleton very well and keeps it safer than other methods.
How do we use relative age dating techniques to order rock layers?
The Law of Superposition states that any fossils above one are younger than any below it.
How do we use radiometric techniques to get the exact age of a rock or fossil?
Radioactive atoms decay at a predictable rate which we can measure to see how much is left to tell how long ago something formed.
What can an imprint possibly tell us or show us that a fossil cannot?
How it moved through bones and more details about the thing like maybe more leaves or spiky parts for a plant or more sharp claws or maybe how heavy an animal was.
Explain the difference between the Typological and Populationist approaches to assigning species names. (From the Record of time reading)
People who take the typological approach believe that even minor or small differences make similar fossils completely different species while those who take the populationist approach (the more popular one as of now in the biological scene) believe that many species all may have minor differences so any similar fossils are typically put together to be the same species because different species would show more major differences.
Fluorine analysis
Can be used only as a relative dating method because the rate of decay and the amount of dissolved mineral in the ground water varies from site to site.
