Fossil Formation
What is a fossil?
Preserved evidence or remains of past life.
According to the Law of Superposition, which undisturbed rock layer is usually oldest: the top or the bottom?
The bottom.
Put these eras in order from oldest to most recent: Cenozoic, Paleozoic, Mesozoic.
Paleozoic, Mesozoic, Cenozoic
Is a fossilized footprint a body fossil, a trace fossil or both?
A trace fossil
(An argument could be made for both)
What is evolution?
The change in inherited traits within populations over generations.
What kind of rock most often preserves fossils?
Sedimentary Rock
If a fossil is found in a lower, undisturbed layer than another fossil, which fossil is usually older?
The fossil in the lower layer.
What major event marks the end of the Mesozoic Era?
The mass extinction of dinosaurs.
Is a fossilized shell a body fossil, a trace fossil or both?
A body fossil
What is natural selection?
The process in which organisms with helpful inherited traits are more likely to survive and reproduce.
What usually happens to an organism’s remains before they become a fossil?
They are buried by sedimentary and decompose slowly.
How do volcanic intrusions disrupt the Law of Superposition?
Volcanic intrusions disrupt the Law of Superposition because they are always younger than the rocks they erupt through.
During which era did mammals become especially common and diverse?
The Cenozoic
What do trace fossils provide evidence about?
Evidence of an organism’s activity or behavior, such as walking, digging, or feeding.
What does Australopithecus afarensis (Lucy’s species) show us about how humans evolved?
Lucy shows us that hominids developed the ability to walk on two legs (bipedality) earlier than scientists once believed.
Why are hard parts, such as bones and shells, more likely to fossilize than soft parts?
Hard parts decay more slowly and are more likely to be buried and preserved.
What is an index fossil?
A fossil from an organism that was widespread but lived for a relatively short time, helping scientists compare rock-layer ages.
Name one major event in the Paleozoic Era.
Examples include the rise of many ocean animals, the first land plants, the appearance of early reptiles.
Is a fossilized tooth a body fossil or a trace fossil, or both?
Body fossil or both. It is a part of an animals body. It can also offer clues about an animal's diet.
What evidence do scientists have that whales evolved from land mammals?
Scientists believe whales descended from land mammals because of vestigial leg bones inside of their bodies.
Describe one way minerals can help form a fossil from an organism’s remains.
Minerals can fill spaces in remains or replace parts of them, preserving their shape or structure.
The same index fossil is found in rock layers in both North America and Asia. What can scientists infer about those rock layers?
The layers formed around the same time in Earth's history.
What is the geologic time scale? How is it organized?
The geologic time scale is the record of life and geologic events in Earth’s history. It is organized into eras and periods. Years are not really long enough to organize it.
Scientists find fossilized burrows alongside bones. What can each type of fossil tell scientists about the past?
Bones can show what organisms were like; burrows can provide evidence of their activity and habitat.
How do animals evolve to develop camouflage over long periods of time?
Camouflage helps animals survive so they can blend into their environments. Over time, animals that do not blend into their environments may go extinct because they are over hunted.