One fossil record, multiple time resolutions: Disparate time-averaging of echinoids and mollusks on a Holocene carbonate platform

Kowalewski, Michał; Casebolt, Sahale; Hua, Quan; Whitacre, Katherine; Kaufman, Darrell S.; Kosnik, Matthew A.

doi:10.1130/g39789.1

Cited by 42 publications

(55 citation statements)

References 30 publications

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“…Following their death, these individuals contribute fresh, that is, age 0 shells, resulting in a surficial death assemblage that is a mix of modern shells and those that date to > 10,000 years old. This multimillennial time-averaging is consistent with, or exceeds, averaging reported for molluscan assemblages in marine settings (Flessa et al 1993;Kidwell 1997Kidwell , 2013Carroll et al 2003;Kosnik et al 2009Kosnik et al , 2013Kosnik et al , 2015Kidwell and Tomašových 2013;Dexter et al 2014;Dominguez et al 2016;Kowalewski et al 2018;Tomašových et al 2019) and vertebrate fluvial assemblages (Behrensmeyer 1982;Aslan and Behrensmeyer 1996).…”

Section: Death Assemblage Taphonomic Provenance and Pathwayssupporting

confidence: 85%

“…Taphonomic processes that affect freshwater invertebrates in fluvial environments are critically understudied compared with those that operate in marine (Kidwell and Bosence 1991;Kowalewski and Labarbera 2004; do Nascimento Ritter 2020), terrestrial (Yanes et al 2008(Yanes et al , 2011, lagoon (do Nascimento Ritter et al 2013), and lacustrine settings (Cohen 1989;Cummins 1994;Alin and Cohen 2004;Hassan et al 2014; Cristini and de Francesco 2017; Pisano et al 2017; Tietze and de Francesco geologic timescales, springs and rivers represent ephemeral systems, as spring discharge decreases and river channels migrate (Gray 1988;Taylor 1988). Considering these factors, one might expect that freshwater shells would be quickly dissolved or otherwise destroyed and, consequently, that freshwater mollusk death assemblages, that is, the loose, surficial accumulation of shell material in these systems, would not undergo the extensive centennial-to-millennial time-averaging that is often observed in marine systems (Flessa et al 1993;Kidwell 1997;Carroll et al 2003;Krause et al 2010;Scarponi et al 2013;Tomašových et al 2014;Kosnik et al 2015;Dominguez et al 2016;Kowalewski et al 2018). Furthermore, formation of such death assemblages may be complicated by input from multiple sources, making interpretation of a fluvial system's historical ecology difficult (Kotzian and Simões 2006;Leorri and Martin 2009).…”

Section: Introductionmentioning

confidence: 99%

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Live, dead, and fossil mollusks in Florida freshwater springs and spring-fed rivers: Taphonomic pathways and the formation of multisourced, time-averaged death assemblages

et al. 2020

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Taphonomic processes are informative about the magnitude and timing of paleoecological changes but remain poorly understood with respect to freshwater invertebrates in spring-fed rivers and streams. We compared taphonomic alteration among freshwater gastropods in live, dead (surficial shell accumulations), and fossil (late Pleistocene–early Holocene in situ sediments) assemblages from two Florida spring-fed systems, the Wakulla and Silver/Ocklawaha Rivers. We assessed taphonomy of two gastropod species: the native Elimia floridensis (n = 2504) and introduced Melanoides tuberculata (n = 168). We quantified seven taphonomic attributes (aperture condition, color, fragmentation, abrasion, juvenile spire condition, dissolution, and exterior luster) and combined those attributes into a total taphonomic score (TT). Fossil E. floridensis specimens exhibited the greatest degradation (highest TT scores), whereas live specimens of both species were least degraded. Specimens of E. floridensis from death assemblages were less altered than fossil specimens of the same species. Within death assemblages, specimens of M. tuberculata were significantly less altered than specimens of E. floridensis, but highly degraded specimens dominated in both species. Radiocarbon dates on fossils clustered between 9792 and 7087 cal BP, whereas death assemblage ages ranged from 10,692 to 1173 cal BP. Possible explanations for the observed taphonomic patterns include: (1) rapid taphonomic shell alteration, (2) prolonged near-surface exposure to moderate alteration rates, and/or (3) introduction of reworked fossil shells into surficial assemblages. Combined radiocarbon dates and taphonomic analyses suggest that all these processes may have played a role in death assemblage formation. In these fluvial settings, shell accumulations develop as a complex mixture of specimens derived from multiple sources and characterized by multimillennial time-averaging. These findings suggest that, when available, fossil assemblages may be more appropriate than death assemblages for assessing preindustrial faunal associations and recent anthropogenic changes in freshwater ecosystems.

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Section: Death Assemblage Taphonomic Provenance and Pathwayssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Live, dead, and fossil mollusks in Florida freshwater springs and spring-fed rivers: Taphonomic pathways and the formation of multisourced, time-averaged death assemblages

et al. 2020

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“…Multiple examples of co-occurring shells of mollusks and brachiopods have been shown to differ significantly in median ages and time averaging (Kosnik et al, 2009(Kosnik et al, , 2013Krause et al, 2010;Tomašových et al, 2014Tomašových et al, , 2019. Such differences can be generated by intrinsic factors like between-species variation in skeletal durability (Kosnik et al, 2007;Kowalewski et al, 2018), in timing and duration of shell production (Tomašových et al, 2016), or in propensity to out-of-habitat transport. These intrinsic factors can be modulated or overwhelmed by gradients in extrinsic factors that influence burial and disintegration, such as sedimentation rates (Krause et al, 2010) and pore-water chemistry (Best et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Radiocarbon dating supports bivalve-fish age coupling along a bathymetric gradient in high-resolution paleoenvironmental studies

Albano

Hua

Kaufman

et al. 2020

Geology

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Studies of paleocommunities and trophic webs assume that multispecies assemblages consist of species that coexisted in the same habitat over the duration of time averaging. However, even species with similar durability can differ in age within a single fossil assemblage. Here, we tested whether skeletal remains of different phyla and trophic guilds, the most abundant infaunal bivalve shells and nektobenthic fish otoliths, differed in radiocarbon age in surficial sediments along a depth gradient from 10 to 40 m on the warm-temperate Israeli shelf, and we modeled their dynamics of taphonomic loss. We found that, in spite of the higher potential of fishes for out-of-habitat transport after death, differences in age structure within depths were smaller by almost an order of magnitude than differences between depths. Shell and otolith assemblages underwent depth-specific burial pathways independent of taxon identity, generating death assemblages with comparable time averaging, and supporting the assumption of temporal and spatial co-occurrence of mollusks and fishes.

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“…; but see Kowalewski et al . ). Furthermore, the magnitude of time‐averaging (interquartile range of ages) generally does not vary according to depth (e.g.…”

mentioning

confidence: 97%

“…Individually dating shallow-water marine mollusc death assemblages has revealed that they are mostly composed of shells with ages approximately spanning from contemporary to >10,000 years old, and shells predating the Holocene are rare (Kidwell & Bosence 1991;Kowalewski et al 1998;Krause et al 2010;Kidwell 2013;Dexter et al 2014;Dominguez et al 2016;Ritter et al 2017). Commonly, timeaveraging does not vary within taxa from the same habitat (Krause et al 2010; but see Kowalewski et al 2018). Furthermore, the magnitude of time-averaging (interquartile range of ages) generally does not vary according to depth (e.g.…”

mentioning

confidence: 99%

Depth as an overarching environmental variable modulating preservation potential and temporal resolution of shelly taphofacies

Ritter

Erthal

Coimbra

2019

LET

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In the marine realm, the interpretation of taphofacies relies heavily on how oceanographic and sedimentary conditions affect the preservation state of fossils. Several taphonomic variables either covary with depth or are directly influenced by depth. Facies‐level factors rather than broad, basin‐scale parameters influence the taphonomic profile of mollusc death assemblages according to actualistic and experimental evidence. To determine the possible relation between depth and the taphonomic conditions of multiple species of bivalve remains, we used seven samples gathered over a comprehensive bathymetric gradient (from 7 to 150 m below mean sea level; topmost 10‐ to 20‐cm layer, roughly corresponding to the taphonomically active zone). We selected samples from predominantly muddy facies on the southern Brazilian shelf (SBS). The taphonomic damage profile (TDP) was measured using site samples based on a standard taphonomic analysis (categorical scoring system) of shells and fragments larger than 4 mm, to identify site damage patterns. Restricting the sedimentary grain size (samples from fine sediments) enabled the determination of the variation in damage with depth among the samples. Constrained analysis of proximities (CAP) revealed that up to 46% of the taphonomic variation observed was related to variation in depth (with approximately 28% unexplained by environmental factors). Part of the unexplained fraction was due to the effect of temporal mixing, which is predictable along large‐scale patches but is inversely linked to the TDP. Our results show that taphonomic analysis, considering large spatial scales in recent environments, can explain the variations present in shell beds that formed during distinct time periods of the evolution of a Quaternary sedimentary basin.

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One fossil record, multiple time resolutions: Disparate time-averaging of echinoids and mollusks on a Holocene carbonate platform

Cited by 42 publications

References 30 publications

Live, dead, and fossil mollusks in Florida freshwater springs and spring-fed rivers: Taphonomic pathways and the formation of multisourced, time-averaged death assemblages

Live, dead, and fossil mollusks in Florida freshwater springs and spring-fed rivers: Taphonomic pathways and the formation of multisourced, time-averaged death assemblages

Radiocarbon dating supports bivalve-fish age coupling along a bathymetric gradient in high-resolution paleoenvironmental studies

Depth as an overarching environmental variable modulating preservation potential and temporal resolution of shelly taphofacies

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