cHAPTER 18-19 TEST Flashcards
A species that has dies out
extinct
Most fossils are preserved in_________ _________
Sedimentary Rock
Preserved remains or traces of ancient life
Fossils
Scientists who study fossils are called
Paleontologists
Relative dating and and radiometric dating are used to
Determine the age of fossils
__________ ___________ establishes the relative age of fossils
relative dating
_________ _________ represent species that lived for a short period of time but over a wide geographic range.
Index fossils
__________ __________ determines a fossils approximate age in years by finding the proportion of radioactive to nonreactive isotypes in a sample
Radiometric dating
__________-__________ is the length of time needed for half of the radioactive atoms in a sample to decay
HALF-LIFE
A fossils age is calculated from the ______-_________ and the amount of remaining ________ ________ the fossil contains
half-life
radioactive atoms
Extinction caused by the slow process of natural selection
background extinction
______ ____________ affect huge numbers of species over a relatively short time.
Mass extinctions
The idea that evolution occurs slowly and gradually is called
gradualism
__________ ___________, long periods of little or no change are interrupted by short periods of rapid change.
punctuated equilibrium
The process in which a single species evolves into diverse species that live in different ways.
Adaptive radiation
