Fossils Flashcards
Inheritance, Variation, and Evolution (12 cards)
What are fossils?
Remains of plants and animals from millions of years ago found in rocks
Fossils provide evidence that organisms lived ages ago.
How do fossils form?
Fossils form in one of three ways:
* Gradual replacement by minerals
* Casts and impressions
* Preservation in places where no decay happens
What is the most common way fossils are formed?
From gradual replacement by minerals
Most fossils happen this way.
What happens to hard parts of organisms when they are buried?
They are eventually replaced by minerals as they decay, forming a rock-like substance shaped like the original hard part.
What is a cast in fossil formation?
A cast is formed when an organism is buried in soft material like clay, which hardens around it as the organism decays.
What types of things can leave impressions in soft materials?
Footprints and rootlet traces
These impressions occur when the material is soft and later hardens.
What environments prevent decay in fossil preservation?
Amber, tar pits, glaciers, and peat bogs
These environments lack oxygen, moisture, or are too cold or acidic for decay microbes.
What is one hypothesis about the origin of life?
The first life forms may have come into existence in a primordial swamp or under the sea.
What is a challenge in supporting hypotheses about the origin of life?
The fossil record is incomplete due to many early life forms being soft-bodied, which decay completely.
What geological activity can destroy fossils?
Movement of tectonic plates can crush fossils already formed in the rock.
Fill in the blank: Fossils show how much or how little different organisms have changed (_______) over millions of years.
evolved
True or False: There is a consensus on how life first began.
False
Various hypotheses exist, but no one really knows.
