Body Size Evolution Across the Geozoic

Smith, Felisa A.; Payne, Jonathan L.; Heim, Noel A.; Balk, Meghan A.; Finnegan, Seth; Kowalewski, Michał; Lyons, S. Kathleen; McClain, Craig R.; McShea, Daniel W.; Novack-Gottshall, Philip M.; Anich, Paula Spaeth; Wang, Steve C.

doi:10.1146/annurev-earth-060115-012147

Cited by 66 publications

(66 citation statements)

References 154 publications

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“…Organ-grade metazoans express a fundamentally greater repertoire of habits and interactions than their unicellular counterparts, not least the dramatically enhanced levels of Among the most obvious and characteristic features of the Cambrian 'explosion' is a dramatic increase in maximum body size, culminating in metre-long anomalocaridids 41 . No less impressive, considering the competitive demands on early meiobenthic pioneers, is the extremely small size of Cambrian loriciferans.…”

Section: Early Evolution Of the Metazoan Meiobenthosmentioning

confidence: 99%

Exceptionally preserved Cambrian loriciferans and the early animal invasion of the meiobenthos

Harvey

Butterfield

2017

Nat Ecol Evol

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Microscopic animals that live among and between sediment grains (meiobenthic metazoans) are key constituents of modern aquatic ecosystems, but are effectively absent from the fossil record. Here we describe an assemblage of microscopic fossil loriciferans (Ecdysozoa, Loricifera) from the late Cambrian Deadwood Formation of western Canada. The fossils share a characteristic head structure and minute adult body size (c. 300 µm) with modern loriciferans, indicating the early evolution and subsequent conservation of an obligate, permanently meiobenthic lifestyle. The unsuspected fossilization potential of such small animals in marine mudstones offers a new search image for the earliest ecdysozoans and other animals, even while the anatomical complexity of loriciferans points to their evolutionary miniaturization from a larger-bodied ancestor. The invasion of animals into ecospace previously monopolized by protists will have contributed importantly to the revolutionary geobiological feedbacks of the Proterozoic-Phanerozoic transition.

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Section: Early Evolution Of the Metazoan Meiobenthosmentioning

confidence: 99%

Exceptionally preserved Cambrian loriciferans and the early animal invasion of the meiobenthos

Harvey

Butterfield

2017

Nat Ecol Evol

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“…A marine megafauna of comparable size returned in the Paleogene, with the new diversification of neoselachian elasmobranchs (Kriwet and Benton, 2004) and the evolution of large marine mammals: Eocene archaeocetes (Uhen, 2008;Gingerich et al, 2009) and Oligocene odontocetes and mysticetes (Gingerich, 2005;Marx and Uhen, 2010;Berta, 2012;Marx et al, 2016) empowered by high metabolic rates and new anatomic features (Armfield et al, 2013). Among the largest vertebrates of all times, after a dramatic size increase at the outset of glacial age (Marx et al, 2016;Bisconti et al, 2017;Slater et al, 2017), baleen and sperm whales are among today's ocean's ecosystem engineers (Roman et al, 2014) with which to compare their Mesozoic analogues (Smith et al, 2016). Notwithstanding a crucial role in ecology and evolution, the nature and distribution of the MM fossil record has been less explored, compared to that of marine invertebrates and terrestrial vertebrates.…”

Section: Introductionmentioning

confidence: 99%

Pliocene stratigraphic paleobiology in Tuscany and the fossil record of marine megafauna

Dominici

Danise

Benvenuti

2018

Earth-Science Reviews

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Tuscany has a rich Pliocene record of marine megafauna (MM), including mysticetes, odontocetes, sirenians and seals among the mammals, and six orders of sharks among the elasmobranchs. This is reviewed with respect to paleogeography and sequence-stratigraphy in six different basins. Conditions at the ancient seafloor are explored by means of sedimentary facies analysis, taphonomy and multivariate techniques applied to a large quantitative dataset of benthic molluscs. MM is rare or absent in most basins during the Zanclean, except in one basin, and most abundant in Piacenzian deposits in all six basins. MM occurs preferentially in fine-grained, shelfal highstand-deposits of small-scale depositional sequences, or at condensed horizons of the maximum flooding interval. It is rare in shallow marine paleonvironments and nearly absent in bathyal paleosettings. Paleogeographic and paleoecological evidence and a comparison with modern patterns of marine upwelling suggest that a wedge of nutrient-rich waters sustained in the offshore during the Pliocene a high biomass of primary producers and a community of apex consumers and mesopredators, similarly to the modern northwestern Mediterranean Sea, with a species-richness higher than the modern and a more complex trophic structure. The highest MM diversity coincides with the mid-Piacenzian warm period, suggesting that facies control does not obscure a link between climate and diversity. We underline however that not all marine environments were suitable for marine mammal preservation. Buoyant carcasses were preferentially dismembered and destroyed in high-energy shallow waters, with the possible exception of delta front deposits, where sudden sediment input occasionally buried pristine carcasses. We hypothesise that carcasses sunken on the seafloor below the shelf break underwent destruction through the activity of a whale-fall biota of modern type, specialised in the consumption of decomposing tissues, both soft and mineralised. A taphonomic window was left between storm wave base and the shelf break. Here water pressure is high enough to prevent the formation of decomposing gases and the resurfacing of carcasses, while the lack of a specialised whale-fall biota slows down bone degradation with respect to deeper settings. Sedimentation rate was high enough to cover skeletal material before its complete destruction. An estimate of paleobathymetries based on multivariate techniques suggests that the preferential depth for the inclusion of MM in the fossil record was 30-300 m. The results are compared with major Mesozoic and Cenozoic MM records worldwide. Available evidence suggests that the late Neogene radiation of large whales, true ecosystem engineers, and their size increase, triggered the radiation of a bone-eating fauna that hampered, and hampers, MM preservation in the deep sea. Stratigraphic paleobiology and an ecosystem-level approach deliver useful insights to the nature of the fossil record.

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“…Body size may inform on organisms’ adaptations to changing environments, and through selection patterns, may reveal the underlying environmental and ecological conditions (Smith et al . ). Furthermore, body size provides an assessment of diversity independent of traditional systematic taxon distinctions (Dommergues et al .…”

Section: Methodsmentioning

confidence: 97%

Ecological revolution of Oklahoma's rhynchonelliform brachiopod fauna during the Great Ordovician Biodiversification Event

Trubovitz

Stigall

2018

LET

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During the Great Ordovician Biodiversification Event (GOBE), the number of marine invertebrate families more than tripled. Fundamental shifts in clade dominance and ecological structure led to the rise of the Palaeozoic Fauna and the second Palaeozoic Ecological Evolutionary Unit (EEU P2 of Sheehan), which revolutionized benthic ecosystems for the next 200 million years. Although general global signals of increased diversity and ecosystem restructuring are known, direct links between these changes are more poorly constrained on high‐resolution local scales. To address this, rhynchonelliformean brachiopod assemblages of the Middle Ordovician Simpson Group (Oklahoma, USA) were assessed before, during and after maximum local diversity increase related to the second global pulse of the GOBE. Stratigraphically constrained brachiopod species occurrence and abundance data were collected for Dapingian‐lower Sandbian strata via field study. Brachiopod assemblages exhibited declining dominance and increasing evenness from the Dapingian through middle Darriwilian stages followed by high volatility in index values during and after the GOBE interval. These patterns document local faunal turnover and shift from EEU P1 to P2. Furthermore, the average species body volume statistically increased over this interval, a pattern that is independent of phylogenetic constraints. Paired increase in mean body size and size disparity is evidence of niche specialization and utilization of additional food resources. Together, changes in body size, evenness and dominance indicate that increasing ecological complexity was coincident with diversification in Oklahoma. This suggests that a common mechanism, such as climate optimization or increased food abundance, was locally responsible for building both taxonomic diversity and ecological complexity during the GOBE.

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Body Size Evolution Across the Geozoic

Cited by 66 publications

References 154 publications

Exceptionally preserved Cambrian loriciferans and the early animal invasion of the meiobenthos

Exceptionally preserved Cambrian loriciferans and the early animal invasion of the meiobenthos

Pliocene stratigraphic paleobiology in Tuscany and the fossil record of marine megafauna

Ecological revolution of Oklahoma's rhynchonelliform brachiopod fauna during the Great Ordovician Biodiversification Event

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