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Natural Selection

Author: Mercer Crouch
Across
the science of determining the relative order of past events
a fossil of a footprint, trail, burrow, or other trace of an animal rather than of the animal itself
the time taken for the radioactivity of a specified isotope to fall to half its original value
a period of time in history or a person's life, typically one marked by notable events or particular characteristics
a technique used to date materials such as rocks or carbon
an organ or bone that appears in different animals, underlining anatomical commonalities demonstrating descent from a common ancestor
the state or process of a species, family, or larger group being or becoming extinct
the remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock
the process whereby organisms better adapted to their environment tend to survive and produce more offspring
surface of contact between two groups of unconformable strata
the gradual development of something, especially from a simple to a more complex form
a fossil that is useful for dating and correlating the strata in which it is found
Down
a long and distinct period of history with a particular feature or characteristic
a change or the process of change by which an organism or species becomes better suited to its environment
a method of dating geological or archeological specimens by determining the relative proportions of particular radioactive isotopes present in a sample
an indefinite and very long period of time, often a period exaggerated for humorous or rhetorical effect
the process of determining an age on a specified time scale in archaeology and geology
the changing of the structure of a gene, resulting in a variant form that may be transmitted to subsequent generations
an English naturalist and geologist, best known for his contributions to evolutionary theory
Similar in function but having different evolutionary origins, as the wings of a butterfly and the wings of a bird