Precise age of Bangiomorpha pubescens dates the origin of eukaryotic photosynthesis

Abstract

Shale samples were collected from outcrops that lack evidence for secondary mineralization from hydrothermal activity and weathered regions that may have experienced alteration were also avoided. Sample sets comprise several 100-200 g samples excavated 10-30 cm from the outcrop surface to target fresh material. Samples were collected along strike from a narrow stratigraphic range (<10 cm), as well as from a vertical profile (up to 5 m). The most organic-rich and least visibly-weathered samples were then chosen for digestion and isotopic

Absence of biomarker evidence for early eukaryotic life from the Mesoproterozoic Roper Group: Searching across a marine redox gradient in mid‐Proterozoic habitability

“…The most parsimonious interpretation of the lack of detectable steranes in our view is that aerobic eukaryotes did not become ecologically widespread and abundant in the global oceans until well into the Neoproterozoic era (Brocks et al., ) and that source biota in mid‐Proterozoic and older oceans were dominated by bacteria (Brocks et al., , ; Flannery & George, ; Isson et al., ; Luo et al., ). A recent molecular clock analysis (Gibson et al., ) predicts that photosynthesis did not actually emerge in Eukarya until ca. 1.25 Ga, and this could help explain the bacterial ecological dominance of Roper Group biomarker assemblages, although the divergence time uncertainties for such estimates can be large and this innovation does not coincide with the ubiquity of eukaryotic steranes in ancient rocks being delayed until ca.…”

Animal origins and the Tonian Earth system

“…Ramathallus, therefore, potentially signals the beginnings of complex multicellularity in stem-group florideophytes ca. 1.6 Ga, although convergent evolution among early, perhaps even stem-group, eukaryotes has been suggested to explain the morphological similarities between Ramathallus and modern florideophytes [43]. Therefore, unless Ramathallus represents multicellular cyanobacteria, complex multicellularity in eukaryotes, or stem-group eukaryotes [43], potentially dates back over 1.6 Ga in the fossil record [42].…”

“…This Neoproterozoic diversification of eukaryotes also correlates with the estimated emergence time of both crown-group animals and crown-group florideophytes ( Figure 3A), although these latter molecular clock estimates exclude the recently described ca. 1.6 Ga Vindhyan fossils, as well as the 1.05 Ga red algal fossil Bangiomorpha pubescens [43], as calibration points [42]. Overall, there is potentially a billion-year gap separating the emergence of the LECA from the emergence of crown-group animals and crown-group florideophytes.…”

“…However, the existence of putative stem-group florideophytes ca. 1.6 Ga challenges the need of a Neoproterozoic rise in atmospheric oxygen -or any other environmental-ecological event in the Neoproterozoic Era, like a rise in eukaryotic predation [6,46] -to permit the evolution of multicellularity in the florideophyte stem lineage [42], or the evolution of multicellularity in florideophyte-like eukaryotes or stem-group eukaryotes [43]. Indeed, the correlation between the estimated age of crown-group florideophytes taxa described per fossiliferous stratigraphic unit), taken from ref.…”

Evolution and expression of core SWI/SNF genes in red algae

“…Red algae attained multicellularity over a billion years ago (Butterfield , Gibson et al. ) and since have acquired substantial genetic, morphological, and ecological diversity. In all that time, however, no member of the Rhodophyta has managed to attain the kinds of cellular and tissue‐level differentiation present in most other eukaryotic lineages that have evolved large, multicellular forms (Murray and Dixon , Brawley et al.…”