Patterns of macroevolution through the Phanerozoic

Abstract

Evolution is seen as a future-blind process driven by ecology. At geological time scales (macroevolution), complex ecosystems (including parasites) have caused periods of relative stasis, while evolutionary change may be fostered by two kinds of exceptional situation: (1) after an extinction event, the availability of open niches gave innovative groups the chance to gain ecologic power; (2) a climatically controlled Golden Age before the event allowed Darwinian optimization to exceed the constructional limits of established bauplans. Increasing specialization, however, automatically raised the vulnerability towards biologically unforeseeable events, because niches become narrower, and conservative (plesiomorphic) features happen to become fatal 'Achilles' heels' under unusual conditions. The interplay between Darwinian diversification and extinctional counter-evolution results in cascading clade histories that resemble individual life cycles without any teleonomic underpinnings. © The Palaeontological Association.