Some of the enigmatic Precambrian organisms in the Ediacaran Period grew large and stood tall above the seafloor. Canopy flow modeling suggests that their large size was optimized for access to flow in order to facilitate osmotrophic nutrient uptake in low-flow environments.

The Precambrian genesis plus Cambrian explosion scenario also implies a perplexing view of a major evolutionary radiation: a long period of cryptic speciation with increasing developmental complexity and anatomical sophistication, yet without substantial behavioural or ecological modification or diversification, followed by a sudden increase in morphological and ecological innovation. Page 1046...

Cyanobacteria are among the most ancient of evolutionary lineages, oxygenic photosynthesizers that may have originated before 3.0 Ga, as evidenced by free oxygen levels. Throughout the Precambrian, cyanobacteria were one of the most important drivers of biological innovations, strongly impacting early Earth's environments. At the end of the Archean Eon, they were responsible for the rapid oxyge...

Magmatism, ore genesis and metamorphism are commonly associated processes that define fundamental features of the Earth’s crustal evolution from earliest Precambrian to Phanerozoic [...]

The discovery by Farquhar et al. (1) of mass-independent isotope fractionation of S and S in rocks formed more than ;2 billion years ago (Ga), but not in younger rocks, has boosted the theory postulating a dramatic change from an anoxic to an oxygen-rich atmosphere about 2 Ga. That is because the only known natural process that may cause mass-independent fractionation of both S and S involves a...

The eumetazoan clade of modern animals includes cnidarians, acoels, deuterostomes, and protostomes. Stem group eumetazoans evolved in the late Neoproterozoic, possibly before the Marinoan glaciation, according to a variety of different kinds of evidence. Here, we combine this evidence, including paleontological observations, results from molecular and morphological phylogeny, and paleoecologica...

Three lines of evidence for ancient life on land are paleosols, microfossils, and MISS (microbially induced sedimentary structures). The three appear in the rock record as old as 3.5–2.7 Ga (Hallbauer and van Warmelo 1974; Rye and Holland 2000; Wacey et al. 2008; Johnson et al. 2010; Noffke et al. 2013). The primitive terrestrial biosphere is plausibly as old as the oldest marine biosphere (Sch...

The antiquity and global abundance of the enzyme, RuBisCO, attests to the crucial and longstanding role it has played in the biogeochemical cycles of Earth over billions of years. The counterproductive oxygenase activity of RuBisCO has persisted over billions of years of evolution, despite its competition with the carboxylase activity necessary for carbon fixation, yet hypotheses regarding the ...