The circum-North Atlantic region archives three major late-Mesoproterozoic to Neoproterozoic tectonic episodes, the Grenville–Sveconorwegian and Renlandian orogenies followed by rifting formation of Iapetus Ocean, each is bracketed sedimentary successions that define megasequences. In this context, we summarize sedimentological geochronological data propose a new stratigraphic framework for ico...

The Neoproterozoic Era is of widespread geobiological interest because it marks the critical transition from a world of microbes to one where animals become an established feature of the landscape. Much research into this time period has focused on the ventilation of the oceans, as this is widely considered a primary factor driving the diversification of complex, multicellular life. In this stu...

A growing body of evidence suggests that the deep oceans during early Paleozoic Era were widely oxygen deficient, despite for increased marine oxygenation Neoproterozoic. However, temporal and geographic extents dynamics reducing conditions within these are not well understood. Here, we investigate redox history Drumian through earliest Jiangshanian International Stages Cambrian Period, using c...

The Cambrian appearance of fossils representing diverse phyla has long inspired hypotheses about possible genetic or environmental catalysts of early animal evolution. Only recently, however, have data begun to emerge that can resolve the sequence of genetic and morphological innovations, environmental events, and ecological interactions that collectively shaped Cambrian evolution. Assembly of ...

Introduction According to Anbar & Knoll (2002), the Proterozoic ocean was in a transition stage from euxinic with oxygenated shallow water to the fully oxygenated water column of the present day. Though there is no direct proxy for the concentration of oxygen in the past, carbon and sulfur isotopes help constrain these concentrations. The carbon and sulfur cycles underwent vast transitions in t...

The Cambrian time scale is in a state of flux due to lack reliable geochronological dates which can be tied biostratigraphic scales. Most recent Australian relevant the geochronologic have been determined from Early successions South Australia and Middle Late sedimentary volcanic rocks western Tasmania. This work has based on SHRIMP using zircon standard SL13. reliability these questionable dou...

Although palaeontological evidence from exceptional biota demonstrates the existence of diverse marine communities in the Early Cambrian (approx. 540-520 Myr ago), little is known concerning the functioning of the marine ecosystem, especially its trophic structure and the full range of ecological niches colonized by the fauna. The presence of a diverse zooplankton in Early Cambrian oceans is st...

The oldest annelid fossils are polychaetes from the Cambrian Period. They are representatives of the annelid stem group and thus vital in any discussion of how we polarize the evolution of the crown group. Here, we describe a fossil polychaete from the Early Cambrian Sirius Passet fauna, Pygocirrus butyricampum gen. et sp. nov., with structures identified as pygidial cirri, which are recorded f...

animal life on land. The current benchmark for evidence of plants on land is about 450,000,000 years ago (Late Ordovician). Tantalizing microscopic fossils of chemically resistant spore walls occur in land-derived rocks around the world, and predate this Late Ordovician age by over 50,000,000 years (Upper Cambrian) and possibly beyond. Figuring out what kinds of organisms (algae, primitive plan...

The geological age of the onychophoran crown-group, and when the group came onto land, have been sources of debate. Although stem-group Onychophora have been identified from as early as the Cambrian, the sparse record of terrestrial taxa from before the Cretaceous is subject to contradictory interpretations. A Late Carboniferous species from the Mazon Creek biota of the USA, Helenodora inopinat...