The Diversity of Life Flashcards
Why is fossilization rare?
Most organisms are completely destroyed after death, either being eaten, decayed, or destroyed by geologic processes.
What are the chances of being fossilized largely controlled by?
The makeup of the organism and where it lives.
True or False: Animals without hard mineralized shells have a much better chance of being fossilized that those without.
False, animals with a hard mineralized shell have a better chance of fossilization.
Why does where an animal live important for fossilization?
The chances of being fossilized increase greatly if the body is quickly covered in sediment, because then it is protected from scavengers and other destroying agents.
Where is the best location for rapid burial?
In the ocean.
What type of animals have the best fossil record?
Invertebrates with shells.
What type of animals have the poorest fossil record?
Terrestrial animals with no shells or skeletons.
Define Taphonomy.
The study of how fossils are preserved. The study of everything that happens to an organism from the time it dies until it is fossilized.
What do Taphonomists look for?
Clues that explain what has happened to the organisms after death.
What controls the type of Fossilization?
The environment where the organism was buried.
What is Permineralization?
Occurs when minerals are deposited in pores or other voids in a shell or bone. Makes the material stronger, improving chances of preservation. This is the most common method of fossilizing bone.
What is Replacement?
Replacement is when minerals in the original shell or bone are replaced by new ones. Can be incredibly detailed, the common replacement minerals are pyrite (fool’s gold). It can also be replaced with silica (also makes very detailed replacements).
Why is Silica good for Replacement?
Since silica does not dissolve in acid and the limestone rock does, they can dissolve the rock and leave the fossils behind.
What is Carbonization?
When thin laters of tissue are preserved as films of carbon - leaves and tissues of soft-bodied organisms are often preserved this way.
What are Moulds/Casts?
Sometimes after burial, the original shell material is dissolved - this leaves a void where the shell used to be. There can be either internal or external moulds, that can also be filled at a later time (forming a cast).
