Lower Paleozoic Biostratigraphy of South America: New contributions and advances

G. L. ALBANESI AND G. ORTEGA

Lugar: Barcelona; Año: 2008 p. 115

The early Paleozoic was the most critical time intervalfor the diversification of the biota on planet Earth.This phenomenon was driven by important paleocontinentaland paleoceanographic changes, caused by intensiveplate tectonic and climatic processes. The Cambrianexplosion of life providing bauplans, the great Ordovicianbiodiversification event, the second most importantmass extinction of life in the Phanerozoic that occurredin the Late Ordovician, and the appearance of landplants represent benchmarks in this evolutionary process(e.g., Albanesi et al., 2003; Webby et al., 2004; Munneckeand Servais, 2007; Li et al., 2007)The chronostratigraphic status of the lower Paleozoic,indispensable to correlate globally all of theseimportant events, has changed dramatically in the lastdecade. The International Commission on Stratigraphy(ICS) of the International Union of Geological Sciences(IUGS), through the work of respective subcommissionsfor each time period, has made significant advances inestablishing new global chronostratigraphic references.The Ordovician, Silurian and Devonian systems havebeen fully established and the Cambrian System is beingrapidly reorganized in terms of stages, series and respectiveintra-systemic boundaries to accomplish the internationaltime chart (see most recent advances at ICS-IUGSweb site: www.stratigraphy.org)This Geologica Acta issue is included in a series ofthem that have been published thanks to the editorialefforts carried out by research members of the CONICETwho focus its activity on the lower Paleozoicrecord (see Aceñolaza, 2003 and 2005, and cites herein).A number of contributions on the lower Paleozoic basinresearch, biostratigraphy and paleogeography have beengathered in these issues and makes up a significant dealof basic knowledge on this subject. The present issueconsists of a series of selected papers that were presentedas abstracts in the “9º Congreso Argentino de Paleontologíay Bioestratigrafía” held in Córdoba, Argentina,on September 18-22, 2006. These contributions wereinvited papers from the total presented in the 2nd symposiumof the congress, entitled “Bioestratigrafía delPaleozoico inferior” (i.e. Lower Paleozoic Biostratigraphy).Sixteen co-authors contributed six papers thatcompose this varied volume on lower Paleozoic paleontologicaland biostratigraphic subjects.