We can directly observe microevolution, but the only proof supporting any theses related to mechanisms of macroevolution can be obtained through excavations, comparative anatomy, and, recently, genetic comparisions. Currently, there exist two major hypotheses describing macroevolution. The first one proposes as its main ingredient the accumulation of changes occurring during microevolution. According to the second one, natural selection and standard microevolution mechanisms do not play an important role. Macroevolution is composed of long periods of "stasis" separated by short (in the geological time scale) periods of rapid changes, which determine its direction. Such view is often supported with the fossil data. Defenders of the first theory (macroevolution as a result of accumulation of changes occurring during microevolution) argue however, that the fossil record is incomplete, and it is not necessery to invoke rapid changes of different kind.

Macroevolution consists of, among other things, adaptive radiation and extinction.

•  History of earth abounds with different scale extinctions. Some of them affected only a few species and are considered a part of the "background noise." Some were extinctions on a great scale, which wiped out a large portion of all species from the face of the Earth. There have been five or six such mass extinctions since the Cambrian period.
•  Adaptive radiation means differentiation of ancestral lineages into several derived lines. If there is a vacancy – due to extinction some ecological niches are vacated – others quickly fill them.