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

Abstract

The Palaeozoic Era: an overview of land and sea ecosystems The Palaeozoic Era, lasting from 541-252 million years ago, was a time of dramatic geographical, climatic, and evolutionary changes. During this Era, life experienced a tremendous transformation and many critical macroevolutionary events took place, including important biotic radiations and diversifications, and three of the five major mass extinctions on the Earth history (Raup & Sepkoski 1982). The advent and diversification of most modern metazoan phyla occurred during the Cambrian and Ordovician periods, in the so-called Cambrian Explosion and Great Ordovician Biodiversification Event (GOBE) (Servais et al. 2010). During the Ordovician, tectonic movements lead to a global cooling that culminated in the Hirnantian glaciation and the first of the five major extinction crisis (Sheehan 2001). Shortly after, life recovered and land was colonized during the Silurian by plants and different groups of arthropods, establishing the first forests during the Devonian (Behrensmeyer 1992). The land transformation caused drastic terrestrial changes with the development of new habitats that allowed the appearance of freshwater ecosystems with increasingly complex ecological interactions (Scheckler 2006). In this context, the colonization of terrestrial environments took place by the first tetrapods, constituting one of the most important events in the evolutionary history of vertebrates (Niedźwiedzki et al. 2010). At the same time, diversity-saturation in marine benthic habitats and the high abundance of planktonic food lead to the occupation of the water column by many animal groups, an event known under the name of "the Devonian Nekton Revolution" (Klug et al. 2009). At the end of the Devonian Period, a second major extinction episode occurred at the Frasnian-Famennian boundary in both marine and terrestrial ecosystems (Barash 2016). Life flourished again during the Carboniferous with unprecedented levels of atmospheric oxygen, which lead to the evolution of unusual gigantic body sizes in several non-related groups of animals (Harrison et al. 2010). The end of the Palaeozoic Era was marked by the greatest extinction of the Phanerozoic Eon, the Permo-Triassic extinction, which entailed the loss of as much as 95% of all species on Earth (Benton & Twitchett 2003). All these key events have determined in a large extent the later evolutionary history of life and, as consequence, their study is critical for achieving a proper understanding of the Mesozoic and Cenozoic eras, as well as explaining the current biological, taxonomical and ecological diversity. Fossil Record provides a unique opportunity in this sense, and therefore its understanding is one of the primary goals of palaeontology. This requires undoubtedly a multidisciplinary approach, including systematic, palaeogeographic, palaeoecologic and evolutionary studies that, in a lower scale, are represented in the special volume herein published, grouping some of the contributions presented at the special workshop ...