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Cited by 157Cephalopods and Marine BiologyMarine Invertebrate Physiology and EcologyMarine Biology and Ecology Research

Early metazoan life: divergence, environment and ecology

Open access
Erwin, Douglas H.·2015·Philosophical Transactions of the Royal Society B: Biological Sciences
DOI 10.1098/rstb.2015.0036PMC PMC4650120
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Abstract

Recent molecular clock studies date the origin of Metazoa to 750-800 million years ago (Ma), roughly coinciding with evidence from geochemical proxies that oxygen levels rose from less than 0.1% present atmospheric level (PAL) to perhaps 1-3% PAL O2. A younger origin of Metazoa would require greatly increased substitution rates across many clades and many genes; while not impossible, this is less parsimonious. Yet the first fossil evidence for metazoans (the Doushantuo embryos) about 600 Ma is followed by the Ediacaran fossils after 580 Ma, the earliest undisputed bilaterians at 555 Ma, and an increase in the size and morphologic complexity of bilaterians around 542 Ma. This temporal framework suggests a missing 150-200 Myr of early metazoan history that encompasses many apparent novelties in the early evolution of the nervous system. This span includes two major glaciations, and complex marine geochemical changes including major changes in redox and other environmental changes. One possible resolution is that animals of these still unknown Cryogenian and early Ediacaran ecosystems were relatively simple, with highly conserved developmental genes involved in cell-type specification and simple patterning. In this model, complex nervous systems are a convergent phenomenon in bilaterian clades which occurred close to the time that larger metazoans appeared in the fossil record.

Integrity signals

Registry

Crossref · 10.1098/rstb.2015.0036

Cites

67 of 70 references verified0 citation errors · 3 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

15 of 47 cited sources checked · 10 supported · 1 flagged · accuracy not yet measured

  • Premisecitation

    Geochemical proxies indicate oxygen levels rose from less than 0.1% PAL to perhaps 1-3% PAL O2.

    “evidence from geochemical proxies that oxygen levels rose from less than 0.1% present atmospheric level (PAL) to perhaps 1-3% PAL O 2”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites [36] 36. Lenton TM, Boyle RA, Poulton SW, Shields-Zhou G, Butterfield NJ. 2014 Co-evolution of eukaryotes and ocean oxygenation in the Neoproterozoic era. Nat. Geosci. 7, 257 -265. (doi:10.1038/ngeo2108) source

      “Deep ocean oxygenation and its causes” reports a geochemical proxy signal of ocean oxygenation, but does not give the claimed atmospheric oxygen rise to 1–3% PAL. “Early Neoproterozoic conditions” instead gives a reliable atmospheric lower limit of 0.01 PAL (1% PAL) at the times discussed, not less than 0.1% PAL; the review’s opening section says evidence for a late-Neoproterozoic atmospheric rise is indirect. Page numbers are unavailable in our copy. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites [40] 40. Ader M, Sansjofre P, Halverson GP, Busigny V, Trindade RIF, Kunzmann M, Nogueira AC. 2014 Ocean redox structure across the late Neoproterozoic oxygenation event: a nitrogen isotope perspective. Earth Planet. Sci. Lett. 396, 1-13. (doi:10.1016/j. epsl.2014.03.042) source
    • cites [41] 41. Johnston DT, Poulton SW, Goldberg T, Sergeev VN, Podkovyrov V, Vorob'eva NG, Bekker A, Knoll AH. 2012 Late Ediacaran redox stability and metazoan evolution. Earth Planet. Sci. Lett. 335, 25-35. (doi:10.1016/J.Epsl.2012.05.010) source
  • Premisecitation

    A detailed study of opsins and phototransduction found good support for the classic phylogeny uniting ctenophores, cnidarians and bilaterians.

    “In contrast, a detailed study of opsins and phototransduction found good support for the classic phylogeny with uniting ctenophores, cnidarians and bilaterians [16].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [16] 16. Feuda R, Rota-Stabelli O, Oakley TH, Pisani D. 2014 The comb jelly opsins and the origins of animal phototransduction. Genome Biol. Evol. 6, 1964-1971. (doi:10.1093/gbe/evu154) source

      In “Opsins and Early Animal Evolution: Reciprocal Illumination,” the paper says its opsin results fit best a traditional scenario in which ctenophores, cnidarians, and bilaterians share a common ancestor. But it explicitly cautions that analyses of a single protein family cannot test animal phylogeny, so “good support” for that phylogeny overstates its conclusion. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
  • Premisecitation

    More recent studies support a basal position for the ctenophore clade.

    “more recent studies have attempt to resolve these difficulties and support a basal position for the clade [4,5,11]”
    Quote in the paperNot a substantial claim1 of 3 sources checked
    • cites [4] 4. Ryan JF et al. 2013 The genome of the ctenophore Mnemiopsis leidyi and its implications for cell type evolution. Science 342, 6164. (doi:10.1126/science. 1242592) source
    • cites [5] 5. Moroz LL et al. 2014 The ctenophore genome and the evolutionary origins of neural systems. Nature 510, 109-114. (doi:10.1038/nature13400) source
    • cites [11] 11. Borowiec ML, Lee EK, Chiu JC, Plachetzki DC. In press. Dissecting phylogenetic signal and accounting for bias in whole-genome data sets: a case study of the Metzoa. Mol. Biol. Evol.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Premisecitation

    The missing span includes two major glaciations.

    “This span includes two major glaciations”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [29] 29. Rooney AD, Macdonald FA, Strauss JV, Dudas FO, Hallmann C, Selby D. 2014 Re-Os geochronology and coupled Os-Sr isotope constraints on the Sturtian snowball Earth. Proc. Natl Acad. Sci. USA 111, 51 -56. (doi:10.1073/pnas.1317266110) source
  • Premisecitation

    The first fossil evidence for metazoans (Doushantuo embryos) is about 600 Ma.

    “the first fossil evidence for metazoans (the Doushantuo embryos) about 600 Ma”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [28] 28. Xiao SH, Muscente AD, Chen L, Zhou CM, Schiffbauer JD, Wood AD, Polys NF, Yuan XL. 2014 The Weng'an biota and the Ediacaran radiation of multicellular eukaryotes. Nat. Sci. Rev. 1, 498-520. (doi:10.1093/nsr/nwu061) source

      The Research History section says animal embryos were reported from the Doushantuo Formation at Weng'an, and Stratigraphy, Age Constraints, and Depositional Environment estimates the Weng'an biota at 600–582 Ma. But the Putative Animals and Animal Embryos section calls their animal identity controversial. The paper therefore does not establish the embryos as the first fossil evidence for metazoans. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
  • May combine two claims. 20
  • Classified as probably not a substantial claim. 10

  • May combine two claims.

    Premisecitation

    The results from geochemical proxies suggest an emerging model of redox condition through the late Neoproterozoic, with atmospheric oxygen levels less than 0.1% PAL O2 before approximately 800 Ma and partially oxygenated oceans from approximately 750 to 580 Ma with levels of approximately 1-3% PAL O2.

    “The results from geochemical proxies suggest an emerging model of redox condition through the late Neoproterozoic, with atmospheric oxygen levels less than 0.1% PAL O 2 before approximately 800 Ma and partially oxygenated oceans from approximately 750 to 580 Ma with levels of approximately 1-3% PAL O 2 [36,40,41].”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites [36] 36. Lenton TM, Boyle RA, Poulton SW, Shields-Zhou G, Butterfield NJ. 2014 Co-evolution of eukaryotes and ocean oxygenation in the Neoproterozoic era. Nat. Geosci. 7, 257 -265. (doi:10.1038/ngeo2108) source

      Split into 2 atoms — 0 confirmed, 1 partially supported, 1 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

      Checked by a reasoning model — may be wrong.

      Experimental — accuracy not yet measured
    • cites [40] 40. Ader M, Sansjofre P, Halverson GP, Busigny V, Trindade RIF, Kunzmann M, Nogueira AC. 2014 Ocean redox structure across the late Neoproterozoic oxygenation event: a nitrogen isotope perspective. Earth Planet. Sci. Lett. 396, 1-13. (doi:10.1016/j. epsl.2014.03.042) source
    • cites [41] 41. Johnston DT, Poulton SW, Goldberg T, Sergeev VN, Podkovyrov V, Vorob'eva NG, Bekker A, Knoll AH. 2012 Late Ediacaran redox stability and metazoan evolution. Earth Planet. Sci. Lett. 335, 25-35. (doi:10.1016/J.Epsl.2012.05.010) source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Likely early metazoan embryos have been described from the Doushantuo Formation in south China approximately 600 Ma.

    “likely early metazoan embryos have been described from the Doushantuo Formation in south China approximately 600 Ma [28]”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [28] 28. Xiao SH, Muscente AD, Chen L, Zhou CM, Schiffbauer JD, Wood AD, Polys NF, Yuan XL. 2014 The Weng'an biota and the Ediacaran radiation of multicellular eukaryotes. Nat. Sci. Rev. 1, 498-520. (doi:10.1093/nsr/nwu061) source

  • May combine two claims.

    Premisecitation

    Two extensive glacial episodes occurred during the Cryogenian period: the Sturtian glaciation (716-665 Ma) and the Marinoan glaciation (ca 650-635 Ma).

    “Two extensive glacial episodes occurred during the Cryogenian period: the Sturtian glaciation (716-665 Ma) and the Marinoan glaciation (ca 650 -635 Ma; figure 1) [29].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [29] 29. Rooney AD, Macdonald FA, Strauss JV, Dudas FO, Hallmann C, Selby D. 2014 Re-Os geochronology and coupled Os-Sr isotope constraints on the Sturtian snowball Earth. Proc. Natl Acad. Sci. USA 111, 51 -56. (doi:10.1073/pnas.1317266110) source

      The Abstract says ice reached equatorial latitudes at least twice between 717 and 635 Ma. It gives the Sturtian epoch as 717–662 Ma, rather than 716–665 Ma, and identifies a Marinoan glaciation around 635 Ma but does not establish its onset at 650 Ma. (LLM, conf=0.86)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Premisecitation

    Recent studies suggest that low oxygen levels would not have precluded the origin of metazoans, as was once believed, but are quite likely to have limited their maximum body size.

    “Recent studies suggest that low oxygen levels would not have precluded the origin of metazoans, as was once believed, but are quite likely to have limited their maximum body size [38,42,43].”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites [38] 38. Sperling EA, Frieder CA, Raman AV, Girguis PR, Levin LA, Knoll AH. 2013 Oxygen, ecology and the Cambrian radiation of animals. Proc. Natl Acad. Sci. USA 110, 13 446 -13 451. (doi:10.1073/pnas. 1312778110) source
    • cites [42] 42. Knoll AH, Sperling EA. 2014 Oxygen and animals in Earth history. Proc. Natl Acad. Sci. USA 111, 3907-3908. (doi:10.1073/pnas.1401745111) source
    • cites [43] 43. Sperling EA, Halverson GP, Knoll AH, Macdonald FA, Johnston DT. 2013 A basin redox transect at the dawn of animal life. Earth Planet. Sci. Lett. 371, 143 -155. (doi:10.1016/J.Epsl.2013.04.003) source

  • May combine two claims.

    Premisecitation

    Ctenophores, cnidarians and bilaterians have experienced independent expansions of the major families of ion-channel proteins, as well as several rounds of gene loss, with no evidence for a rapid increase in complexity associated with the origin of nerves.

    “A reconstruction of the evolutionary history of ion channel genes established that ctenophores, cnidarians and bilaterians have experienced independent expansions of the major families of ion-channel proteins, as well as several rounds of gene loss, with no evidence for a rapid increase in complexity associated with the origin of nerves [53].”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [53] 53. Liebeskind BJ, Hillis DM, Zakon HH. 2015 Convergence of ion channel genome content in early animal evolution. Proc. Natl Acad. Sci. USA 112, E846-E851. (doi:10.1073/pnas.1501195112) source

  • May combine two claims.

    Premisecitation

    The ion channel data are most consistent with the early origin of 'very rudimentary' nervous systems that persisted for a long time before the independent and convergent expansion of channel complexity.

    “This study emphasized that the ion channel data are most consistent with the early origin of 'very rudimentary' nervous systems that persisted for a long time before the independent and convergent expansion of channel complexity.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [53] 53. Liebeskind BJ, Hillis DM, Zakon HH. 2015 Convergence of ion channel genome content in early animal evolution. Proc. Natl Acad. Sci. USA 112, E846-E851. (doi:10.1073/pnas.1501195112) source

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    Comparative studies of the development of living animals support conflicting interpretations of the probable morphology of animals during this time.

    “Comparative studies of the development of living animals support conflicting interpretations of the probable morphology of animals during this time.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    One possible resolution is that animals of the still unknown Cryogenian and early Ediacaran ecosystems were relatively simple, with highly conserved developmental genes involved in cell-type specification and simple patterning.

    “One possible resolution is that animals of these still unknown Cryogenian and early Ediacaran ecosystems were relatively simple, with highly conserved developmental genes involved in cell-type specification and simple patterning.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Kimberella could be a stem mollusc but is certainly a stem lophotrochozoan.

    “which could be a stem mollusc but is certainly a stem lophotrochozoan [20,21]”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [20] 20. Fedonkin MA, Simonetta A, Ivantsov AY. 2007 New data on Kimberella, the Vendian mollusc-like rstb.royalsocietypublishing.org Phil. Trans. R. Soc. B 370: 20150036 organism (White Sea region, Russia): paleontological and evolutionary implications. In The rise and fall of the Ediacaran biota (eds P Vickers-Rich, P Komarower), pp. 157-179. London, UK: Geological Society. source
    • cites [21] 21. Vinther J. 2015 The origins of molluscs. Palaeontology 58, 19-34. (doi:10.1111/pala.12140) source

  • May combine two claims.

    Interpretationcitation

    The absence of evidence for macroscopic metazoans before 579 Ma, or bilaterians until after 555 Ma is consistent with a role for oxygen levels in controlling body size, rather the origin of clades.

    “The absence of evidence for macroscopic metazoans before 579 Ma, or bilaterians until after 555 Ma is consistent with a role for oxygen levels in controlling body size, rather the origin of clades.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    The relationships between most animal groups have been satisfactorily established through molecular phylogenetics.

    “The relationships between most animal groups have been satisfactorily established through molecular phylogenetics (figure 1).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    The origin and early divergence of animals occurred from the Cryogenian into the Ediacaran and Cambrian periods.

    “The origin and early divergence of animals occurred from the Cryogenian (ca 850-635 Ma) into the Ediacaran (635-542 Ma) and Cambrian periods”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    These results imply that many metazoan lineages must have been present during the Ediacaran, not only sponges, cnidarians, but also stem groups of arthropods, priapulids, annelids, molluscs, brachiopods, vertebrates, echinoderms, hemichordates and others.

    “these results imply that many metazoan lineages must have been present during the Ediacaran, not only sponges, cnidarians, but also stem groups of arthropods, priapulids, annelids, molluscs, brachiopods, vertebrates, echinoderms, hemichordates and others.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [1] 1. Erwin DH, Laflamme M, Tweedt SM, Sperling EA, Pisani D, Peterson KJ. 2011 The Cambrian conundrum: early divergence and later ecological success in the early history of animals. Science 334, 1091 -1097. (doi:10.1126/science.1206375) source

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationreasoning

    In this model, complex nervous systems are a convergent phenomenon in bilaterian clades.

    “complex nervous systems are a convergent phenomenon in bilaterian clades”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    The Cryogenian and Ediacaran were intervals of pervasive environmental changes, many unlike anything in the past 540 million years.

    “The Cryogenian and Ediacaran were intervals of pervasive environmental changes, many of them unlike anything that has occurred in the past 540 million years”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    This implies a missing 150-200 Myr of early history of metazoans, a span encompassing most of the critical episodes in the evolution of nervous systems.

    “This implies a missing 150-200 Myr of early history of metazoans, a span encompassing most of the critical episodes in the evolution of nervous systems.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given

    The Cambrian radiation begins about 542 Ma with a suite of small shelly fossils, most of which were probably of lophotrochozoan affinities.

    “The Cambrian radiation begins about 542 Ma with a suite of small shelly fossils, most of which were probably of lophotrochozoan affinities.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationcitation

    Integration of molecular clock and fossil data suggests that metazoans originated during the Cryogenian, perhaps 780 Ma, and diversified into many of the major clades through the Cryogenian and Ediacaran.

    “integration of molecular clock and fossil data suggests that metazoans originated during the Cryogenian, perhaps 780 Ma, and diversified into many of the major clades through the Cryogenian and Ediacaran.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisenone given

    The enigmatic macrofossils of the Ediacaran range from 578 to 542 Ma.

    “followed by the enigmatic macrofossils of the Ediacaran, ranging from 578 to 542 Ma.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationnone given

    In either case, body size of early metazoans must have been small with limited developmental patterning of the embryo and a lack of complex morphogenetic patterning.

    “In either case, body size of early metazoans must have been small with limited developmental patterning of the embryo and a lack of complex morphogenetic patterning.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Interpretationnone given

    The absence of any fossil record of animals during the Cryogenian and early Ediacaran establishes that animals alive during this interval lacked a skeleton and were not easily fossilizable.

    “The absence of any fossil record of animals during the Cryogenian and early Ediacaran establishes that animals alive during this interval lacked a skeleton and were not easily fossilizable.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The fossil record is complete enough that the absence of fossils of animals in the Cryogenian and early Ediacaran indicates that animals then lacked skeletons and were not easily fossilizable.

  • May combine two claims.

    Premisecitation

    By approximately 650 Ma, the bilaterian LCA was more highly tuned for direct interaction with environment and exhibited both anterior/posterior and dorsal/ventral regional patterning and elaboration.

    “By approximately 650 Ma, the bilaterian LCA was more highly tuned for direct interaction with environment and exhibited both anterior/posterior and dorsal/ventral regional patterning and elaboration.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [46] 46. Tweedt SM, Erwin DH. 2015 Origin of metazoan developmental toolkits and their expression in the fossil record. In Evolution of multicellularity (eds I Ruiz-Trillo, AM Nedelcu), pp. 47 -78. Dordrecht, The Netherlands: Springer. source
    • The authors state this as an assumption: Sponges are basal to metazoans.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given

    This increased morphogenetic patterning was often accomplished by co-option of developmental processes initially established for simpler processes.

    “This increased morphogenetic patterning was often accomplished by co-option of developmental processes initially established for simpler processes.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Transcription factors for cell-type specification were present in early metazoan LCAs, producing limited regional patterning of the body and a loosely controlled body plan.

    “Transcription factors for cell-type specification were present, producing limited regional patterning of the body and a loosely controlled body plan.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [46] 46. Tweedt SM, Erwin DH. 2015 Origin of metazoan developmental toolkits and their expression in the fossil record. In Evolution of multicellularity (eds I Ruiz-Trillo, AM Nedelcu), pp. 47 -78. Dordrecht, The Netherlands: Springer. source
    • The authors state this as an assumption: Sponges are basal to metazoans.

  • May combine two claims.

    Premisecitation

    The sponge-cnidarian LCA, the cnidarian-bilaterian LCA and the bilaterian LCA generally lacked the complicated morphogenetic developmental pathways observed in modern bilaterians, assuming sponges are basal to metazoans.

    “the sponge-cnidarian LCA (demosponge-cnidarian LCA if sponges are paraphyletic), the cnidarian-bilaterian LCA and the bilaterian LCA generally lacked the complicated morphogenetic developmental pathways observed in modern bilaterians.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [46] 46. Tweedt SM, Erwin DH. 2015 Origin of metazoan developmental toolkits and their expression in the fossil record. In Evolution of multicellularity (eds I Ruiz-Trillo, AM Nedelcu), pp. 47 -78. Dordrecht, The Netherlands: Springer. source
    • The authors state this as an assumption: Sponges are basal to metazoans.

  • May combine two claims.

    Interpretationreasoning

    The absence of trace fossils indicates that any mobile, benthic forms must have been less than 1 cm in maximum dimension, and had a metabolic rate consistent with shallow marine oxygen levels of 1-3% PAL.

    “The absence of trace fossils indicates that any mobile, benthic forms must have been less than 1 cm in maximum dimension (in some environments even smaller forms can be detected), and had a metabolic rate consistent with shallow marine oxygen levels of 1-3% PAL.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    The cnidarian-bilaterian LCA possessed a mouth, gut and multifunctional cells.

    “This LCA possessed a mouth, gut and multifunctional cells.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [46] 46. Tweedt SM, Erwin DH. 2015 Origin of metazoan developmental toolkits and their expression in the fossil record. In Evolution of multicellularity (eds I Ruiz-Trillo, AM Nedelcu), pp. 47 -78. Dordrecht, The Netherlands: Springer. source
    • The authors state this as an assumption: Sponges are basal to metazoans.

  • May combine two claims.

    Premisecitation

    These match closely with estimates from the fossil record, except for crown demosponges and crown cnidarians, which occur in the Cryogenian.

    “These match closely with estimates from the fossil record, except for crown demosponges and crown cnidarians, which occur in the Cryogenian.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [1] 1. Erwin DH, Laflamme M, Tweedt SM, Sperling EA, Pisani D, Peterson KJ. 2011 The Cambrian conundrum: early divergence and later ecological success in the early history of animals. Science 334, 1091 -1097. (doi:10.1126/science.1206375) source
    • Rests on an assumption: The origin of basal metazoan clades occurred during the Cryogenian and early Ediacaran, to about 600 Ma.
28 of 28

  • The paper relies on this without support.

    The fossil record is complete enough that the absence of fossils of animals in the Cryogenian and early Ediacaran indicates that animals then lacked skeletons and were not easily fossilizable.

    “The absence of any fossil record of animals during the Cryogenian and early Ediacaran establishes that animals alive during this interval lacked a skeleton and were not easily fossilizable.”

  • The authors state this as an assumption.

    Sponges are basal to metazoans.

    “assuming that sponges are basal to metazoans”

  • The paper relies on this without support.

    The origin of basal metazoan clades occurred during the Cryogenian and early Ediacaran, to about 600 Ma.

    “The origin of basal metazoan clades occurred during the Cryogenian and early Ediacaran, to about 600 Ma.”

  • The paper relies on this without support.

    During the Cryogenian and early Ediacaran, oxygen concentrations were low and unstable.

    “During this time, oxygen concentrations were low and unstable, probably placing primacy on opportunistic life strategies with easy dispersal.”

  • The paper relies on this without support.

    During the Ediacaran-Cambrian radiation, environmental conditions began to ameliorate.

    “During the Ediacaran-Cambrian radiation (ECR) environmental conditions began to ameliorate”

  • The paper relies on this without support.

    Glacial activity ended during the ECR.

    “glacial activity ended”

  • The paper relies on this without support.

    There was a decline in the magnitude of perturbations in carbon isotopes during the ECR.

    “there was a decline in the magnitude of perturbations in carbon isotopes”

  • The paper relies on this without support.

    There was an increase in oxygen levels in the deep and shallow oceans, especially after 555 Ma.

    “an increase in oxygen levels in the deep and shallow oceans, especially after 555 Ma.”

  • The paper relies on this without support.

    Metazoan body sizes increased significantly, first with the appearance of the Ediacaran macrofauna after 579 Ma, and then with the appearance of larger-bodied bilaterians in the early Cambrian.

    “Metazoan body sizes increased significantly, first with the appearance of the Ediacaran macrofauna after 579 Ma, and then with the appearance of larger-bodied bilaterians in the early Cambrian.”

  • The paper relies on this without support.

    Both these phases of the ECR were accompanied by increases in the complexity of developmental patterning.

    “Both these phases of the ECR were accompanied by increases in the complexity of developmental patterning.”

  • The paper relies on this without support.

    Ecological complexity increased rapidly, particularly near the Ediacaran-Cambrian boundary.

    “Ecological complexity increased rapidly, particularly near the Ediacaran-Cambrian boundary”

  • The paper relies on this without support.

    Feeding at this node was likely via proto-epithelial filter-feeding.

    “Feeding at this node was likely via proto-epithelial filter-feeding.”
12 of 12

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Even if the rate of evolution was elevated during the early diversification of animals, or if the evolution of higher taxa such as Panarthropoda was limited to the Phanerozoic, a deep Neoproterozoic history is required to account for the radiation of early animal clades.

    “Even if the rate of evolution was elevated during the early diversification of animals [121, 122], or if the evolution of higher taxa such as Panarthropoda was to be limited to the Phanerozoic [121], a deep Neoproterozoic history is required to account for the radiation of early animal clades [123].”

    From The origin of animals: Can molecular clocks and the fossil record be reconciled? (2017) · cites this paper as [123]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Different dates for the cnidarian-bilaterian ancestor

    Minor

    The paper dates the last common ancestor of cnidarians and bilaterians to approximately 700 Ma in one section and approximately 720 Ma in another. Both are presented as estimates for the same ancestor, without an explanation for the different point estimates.

1 of 1

Cites

Flagged first, then by citations

Research works printed but not linked: 3

  1. Halverson GP, 2011, Memoir 36: The geological record of Neoproterozoic glaciations, 51
  2. Tweedt SM, 2015, Evolution of multicellularity, 47
  3. Mayr E, 1960, The evolution of life, 349

Cited by

Sorted by citations

Related

Authors
Erwin, D. H.
Affiliations
Smithsonian Institution (US)
Corresponding author
Erwin, Douglas H.
ORCID
Erwin, Douglas H.
Venue
Philosophical Transactions of the Royal Society B: Biological Sciences
Publisher
The Royal Society
Published
2015-12-19
Volume
370
Issue
1684
Pages
20150036
ISSN
  • 0962-8436 (ISSN-L)
  • 1471-2970
DOI
10.1098/rstb.2015.0036
PMC
PMC4650120
OpenAlex
W2161156333
Cited by
157
References
66
Citations by year
2026: 28 · 2025: 5 · 2024: 17 · 2023: 13 · 2022: 17 · 2021: 11 · 2020: 12 · 2019: 13 · 2018: 13 · 2017: 14 · 2016: 9 · 2015: 2
FWCI
25.86
Type
journal article
Language
en
Open access
Licence
royalsociety.org/journals/ethics-policies/data-sharing-mining/ (tdm)
Locations
  • Philosophical Transactions of the Royal Society B Biological Sciences (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (submittedVersion)
  • PubMed Central (submittedVersion)
Topics
  • Life Sciences › Agricultural and Biological Sciences › Ecology, Evolution, Behavior and Systematics › Cephalopods and Marine Biology
  • Physical Sciences › Earth and Planetary Sciences › Paleontology › Marine Invertebrate Physiology and Ecology
  • Physical Sciences › Earth and Planetary Sciences › Oceanography › Marine Biology and Ecology Research
Keywords
early metazoan evolution, molecular clock, atmospheric oxygenation, Ediacaran fossils, Cryogenian, bilaterian evolution, nervous system evolution, convergent evolution
MeSH terms
Animals, Biological Evolution, Fossils, Nervous System, Ecosystem

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-11.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-11.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

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