Changes Over Time Crossword Puzzle

Changes Over Time

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Across

Down

a technique used to determine the actual age of a fossil on the basis of the amount of a radioactive element it contains

a technique used to determine which of two fossils is older

a diagram that shows how scientists think different groups of organisms are related

the theory that species evolve during short periods of rapid change

a well-tested concept that explains a wide range of observations

term used to indicate a species that does not have any living members

an unstable element that breaks down into a different element

the process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species

a fossil formed when minerals replace all or part of an organism

any difference between individuals of the same species

a type of fossil formed when a shell or other hard part of an organism dissolves, leaving an empty space in the shape of the part

a type of fossil that forms when a mold becomes filled in with minerals that then harden

body parts that are structurally similar in related species; provide evidence that the structures were inherited from a common ancestor

a trait that helps an organism survive and reproduce

the preserved remains or traces of an organism that lived in the past

the time it takes for half of the atoms in a radioactive element to break down

the theory that evolution occurs slowly but steadily

the gradual change in a species over time

a group of similar organisms that cna mate with each other and produce fertile offspring

Answer