Change Over Time Vocabulary

Species

• A group of physically similar organisms that can
• mate and create offspring that can also do the same

Scientific Theory

• an explanation about some aspect of nature that
• has been confirmed through eperitmenting, facts,
• and creating observations
• The Big Bang is an example of a theory.

Branching Tree

• a diagram that shows how scientists
• believe differing organisms are related

Relative Dating

• a technique that determines which fossil is older

Fossil Record

• all of the fossils scientists have collected

Fossil

• perserved traces or remains of an
• organism that lived in the past

Natural Selection

• a process where organisms that have adapted
• better to their environment are more likely to reproduce
• and live in comparison to others in the same species

Petrified Fossil

• when minerals replace all or some of
• an organism and create a fossil

Radioactive Dating

• a technique used to determine the age of a fossil
• based on how many radioactive elements it contains

Extinct

• dissapearance of a whole species on Earth
• The saber tooth cat is an extinct animal.

Adaptation

• a behavior or physical charasteristic
• that allows an organism to survive and/or
• reproduce in its environment

Variation

• any difference between organisms
• in the same species

Mold

• a fossil form when a hard part of an orgaism
• dissolves and leaves an empty space in the
• shape of the part

Radioactive Element

• an unstable element that breaks down
• into a different element
• Uranium is a radioactive element.

Gradualism

• theory that evolution occurs slowly but steadliy

Evolution

• gradual change in a species over time

Homologous Structures

• body parts that are similar between
• differing species that provide evidence
• for evolution

Cast

• a fossil that forms when minerals
• fill a fossil and then hardens

Half-life

• the time it takes for half of the atoms
• in a radioactive element to decay

Punctuated Equilibria

• a theory that states species evolve during
• short periods of rapid change
• Gradualism (Left) vs. Punctuated Equilibrium (Right)