Paleontology is a major source of data, hypothesis generation, and hypothesis testing in evolutionary studies. The occurrence of distinctive suites of fossils in different strata forms the evidence upon which geological time first was delineated, thus providing the temporal framework for interpreting biological evolution. Fossils have been a major source of data since the advent of evolutionary thinking. Early Darwinian studies employed transformational series of fossils from successive rock layers (i.e., chronoclines) to infer homologies, to document the evolution of organs, and to interpret the evolution of modern groups of organisms. With the advent of quantitative and cladistic methodologies, the role of fossils expanded further to encompass the evolutionary diversification of clades, and to define patterns of phylogeny through time. Other paleontological studies go beyond evolutionary patterns to address evolutionary processes, and to assess the mode and tempo of evolution. For the application of molecular clock reasoning, fossils are the principal means by which such clocks are calibrated and the resulting hypotheses are tested. Most recently, the application of molecular techniques to developmental evolutionary studies has defined another important role for the fossil record. When developmental control mechanisms leave a distinctive morphological or anatomical “fingerprint”, such structure can be used to identify the origin and track the diversification of the mechanisms that define growth patterns. With the continuing addition of new approaches and methodologies, future evolutionary studies will continue to rely heavily upon an accurate interpretation of the past.

Key words: evolution, paleontology, phylogeny