Carbonaceous and siliceous Neoproterozoic vase-shaped microfossils (Urucum Formation, Brazil) and the question of early protistan biomineralization

Morais, Lurdes; Fairchild, Thomas R.; Lahr, Daniel J. G.; Rudnitzki, Isaac Daniel; Schopf, J. William; Garcia, Amanda K.; Kudryavtsev, Anatoliy B.; Romero, Guilherme R.

doi:10.1017/jpa.2017.16

Cited by 42 publications

(71 citation statements)

References 78 publications

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“…In support of the emerging Proterozoic biomarker patterns, fossil evidence for diverse eukaryotic assemblages from multiple locations, including phytoplankton and heterotrophic protists, is also found in the early‐mid Neoproterozoic from about 850 Ma and younger (Butterfield, Knoll, & Swett, ; Knoll, ; Knoll, Javaux, Hewitt, & Cohen, ; Morais et al, ; Porter & Knoll, ; Strauss et al, ). Microfossil analysis is best suited for detecting the earliest eukaryotes in the geological record, but it is difficult to use this approach to semi‐quantitatively assess the eukaryotic abundance relative to bacterial source inputs and relative to the total sedimentary organic matter pool, since the dominant sedimentary organic matter component is amorphous kerogen.…”

Section: Resultsmentioning

confidence: 93%

Free and kerogen‐bound biomarkers from late Tonian sedimentary rocks record abundant eukaryotes in mid‐Neoproterozoic marine communities

2019

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Lipid biomarker assemblages preserved within the bitumen and kerogen phases of sedimentary rocks from the ca. 780-729 Ma Chuar and Visingsö Groups facilitate paleoenvironmental reconstructions and reveal fundamental aspects of emerging mid-Neoproterozoic marine communities. The Chuar and Visingsö Groups were deposited offshore of two distinct paleocontinents (Laurentia and Baltica, respectively) during the Tonian Period, and the rock samples used had not undergone excessive metamorphism. The major polycyclic alkane biomarkers detected in the rock bitumens and kerogen hydropyrolysates consist of tricyclic terpanes, hopanes, methylhopanes, and steranes. Major features of the biomarker assemblages include detectable and significant contribution from eukaryotes, encompassing the first robust occurrences of kerogen-bound regular steranes from Tonian rocks, including 21-norcholestane, 27-norcholestane, cholestane, ergostane, and cryostane, along with a novel unidentified C 30 sterane series from our least thermally mature Chuar Group samples.Appreciable values for the sterane/hopane (S/H) ratio are found for both the free and kerogen-bound biomarker pools for both the Chuar Group rocks (S/H between 0.09 and 1.26) and the Visingsö Group samples (S/H between 0.03 and 0.37). The more organic-rich rock samples generally yield higher S/H ratios than for organic-lean substrates, which suggests a marine nutrient control on eukaryotic abundance relative to bacteria. A C 27 sterane (cholestane) predominance among total C 26 -C 30 steranes is a common feature found for all samples investigated, with lower amounts of C 28 steranes (ergostane and crysotane) also present. No traces of known ancient C 30 sterane compounds; including 24-isopropylcholestanes, 24-n-propylcholestanes, or 26-methylstigmastanes, are detectable in any of these pre-Sturtian rocks. These biomarker characteristics support the view that the Tonian Period was a key interval in the history of life on our planet since it marked the transition from a bacterially dominated marine biosphere to an ocean system which became progressively enriched with eukaryotes. The eukaryotic source organisms likely encompassed photosynthetic primary producers, marking a rise in red algae, and consumers in a revamped trophic structure predating the Sturtian glaciation. K E Y W O R D S eukaryotes, HyPy, lipid biomarkers, Neoproterozoic, steranes | 327 ZUMBERGE Et al.

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Section: Resultsmentioning

confidence: 93%

Free and kerogen‐bound biomarkers from late Tonian sedimentary rocks record abundant eukaryotes in mid‐Neoproterozoic marine communities

2019

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“…, Mayama and Kuriyama , Morais et al. ). The most well‐known protists forming mineral structures are diatoms (Martin‐Jezequel et al.…”

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confidence: 99%

“…Moreover, a lack of structures that could be preserved in sediment leads to a very limited fossil record in protists, which also constrains the proper calibration of phylogenetic analyses (Roger and Hug 2006). Nevertheless, some protist lineages are able to produce minerals preserved in fossil layers by a process of biomineralization (e.g., Bovee 1981, Henriksen et al 1993, Mayama and Kuriyama 2002, Morais et al 2017. The most well-known protists forming mineral structures are diatoms (Martin-Jezequel et al 2000); though, several other clades in Stramenopiles are capable of creating extraordinarily diverse biomineralized structures.…”

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confidence: 99%

Molecular phylogeny and evolution of phenotype in silica‐scaled chrysophyte genus Mallomonas

Čertnerová

Čertner

Škaloud

2019

Journal of Phycology

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The evolution of phenotypes is highly understudied in protists, due to the dearth of morphological characters, missing fossil record, and/or unresolved phylogeny in the majority of taxa. The chrysophyte genus Mallomonas (Stramenopiles) forms species‐specific silica scales with extraordinary diversity of their ornamentation. In this paper, we molecularly characterized three additional species to provide an updated phylogeny of 43 species, and combined this with evaluations of 24 morphological traits. Using phylogenetic comparative methods, we evaluated phylogenetic signal in traits, reconstructed the trait evolution, and compared the overall phylogenetic and morphological diversity. The majority of traits showed strong phylogenetic signal and mostly dynamic evolution. Phylogenetic relatedness was often reflected by the phenotypic similarity. Both V‐rib and dome are very conservative structures that are presumably involved in precise scale overlap and bristle attachment, respectively. Based on modern species, it seems the dome firstly appeared on apical and/or caudal scales, and only later emerged on body scales. Bristle was presumably present in the common ancestor and gradually elongated ever since. However, most other morphological traits readily changed during the evolution of Mallomonas.

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“…Vase-shaped tests are widespread and abundant in marine sediments of the later Tonian Period (ca. 800-725 million years ago) [31][32][33][34]. Most of these fossils show a combination of characters suggestive of amoebozoan affinities, including some populations that closely resemble the tests of extant Arcella species [31].…”

Section: And Discussionmentioning

confidence: 99%

Testate Amoebae in the 407-Million-Year-Old Rhynie Chert

et al. 2019

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Carbonaceous and siliceous Neoproterozoic vase-shaped microfossils (Urucum Formation, Brazil) and the question of early protistan biomineralization

Cited by 42 publications

References 78 publications

Free and kerogen‐bound biomarkers from late Tonian sedimentary rocks record abundant eukaryotes in mid‐Neoproterozoic marine communities

Free and kerogen‐bound biomarkers from late Tonian sedimentary rocks record abundant eukaryotes in mid‐Neoproterozoic marine communities

Molecular phylogeny and evolution of phenotype in silica‐scaled chrysophyte genus Mallomonas

Testate Amoebae in the 407-Million-Year-Old Rhynie Chert

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