Life in the Palaeozoic: an overview of land and sea ecosystems

摘要

The Palaeozoic Era, lasting from 541–252 million years ago, was a time of dramatic geographical, climatic, and evolution-ary changes. During this Era, life experienced a tremendous transformation and many critical macroevolutionary eventstook place, including important biotic radiations and diversifications, and three of the five major mass extinctions on theEarth history (Raup & Sepkoski 1982). The advent and diversification of most modern metazoan phyla occurred during theCambrian and Ordovician periods, in the so-called Cambrian Explosion and Great Ordovician Biodiversification Event(GOBE) (Servaiset al. 2010). During the Ordovician, tectonic movements lead to a global cooling that culminated in theHirnantian glaciation and the first of the five major extinction crisis (Sheehan 2001). Shortly after, life recovered and landwas colonized during the Silurian by plants and different groups of arthropods, establishing the first forests during the Dev-onian (Behrensmeyer 1992). The land transformation caused drastic terrestrial changes with the development of new habi-tats that allowed the appearance of freshwater ecosystems with increasingly complex ecological interactions (Scheckler2006). In this context, the colonization of terrestrial environments took place by the first tetrapods, constituting one of themost important events in the evolutionary history of vertebrates (Nied?wiedzkiet al. 2010). At the same time,diversity-saturation in marine benthic habitats and the high abundance of planktonic food lead to the occupation of thewater column by many animal groups, an event known under the name of “the Devonian Nekton Revolution” (Kluget al.2009). At the end of the Devonian Period, a second major extinction episode occurred at the Frasnian-Famennian boundaryin both marine and terrestrial ecosystems (Barash 2016). Lifeflourished again during theCarboniferous withunprece-dented levels of atmospheric oxygen, which lead to the evolution of unusual gigantic body sizes in several non-relatedgroups of animals (Harrisonet al. 2010). The end of the Palaeozoic Era was marked by the greatest extinction of thePhanerozoic Eon, the Permo-Triassic extinction, which entailed the loss of as much as 95% of all species on Earth (Benton& Twitchett 2003).