Sensitivity of Taphonomic Signatures to Sample Size, Sieve Size, Damage Scoring System, and Target Taxa

Kidwell, Susan M.; Rothfus, Thomas A.; Best, Mairi

doi:10.2307/3515551

Cited by 6 publications

(21 citation statements)

References 14 publications

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“…About 34 samples were collected and deposited in the Palaeontology Collection of the Geology Department (DGEO), Center of Technology and Geosciences (CTG), at Federal University of Pernambuco (UFPE), Pernambuco, Brazil. In the laboratory, a mean of 120 bioclasts (≥ 2 mm) was analyzed in each skeletal accumulation, as proposed by Kidwell et al (2001), to obtain reliable taphonomic results.…”

Section: Methodsmentioning

confidence: 99%

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Tafonomy of macroinvertebrates and Albian marine ingression as recorded by the Romualdo Formation (Cretaceous, Araripe Basin, Brazil)

2018

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The Romualdo Formation, Araripe Basin, crops out in the municipality of Exu, Pernambuco State, exposing coquinas. Fauna survey, taphonomic analysis of the macrobenthos, and identification of sedimentary facies of the outcrop were carried out to contribute to paleoenvironmental understanding of the Romualdo Formation. The association of molluscs (Cerithium sp., Tylostoma ranchariensis, Aguileria dissita, Brachidontes araripensis and unidentified cassiopids) and echinoids of the species Bothryopneustes araripensis suggests sedimentation in the marine environment. The taphonomic similarities made possible the grouping of coquinas into two types. Coquinas type 1 exhibit characteristics of transport and reworking of bioclast generated by storms in proximal setting. Coquinas type 2 demonstrates echinoids in situ and articulated with spines connected to shells, suggesting a fast sedimentation by distal tempestite. Regarding sedimentary facies, the concentrations of invertebrates would have been formed in the transitional offshore zone of siliclastic platform. The results presented here evidence a broader distribution of echinoids and expand the geographic limits of the shallow marine environment in the Romualdo Formation.

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Section: Methodsmentioning

confidence: 99%

“…Macroinvertebrates form fossiliferous concentrations in all layers, except in LCE11, which has a single unidentified closed articulated bivalve. Since samples with less than 20 specimens are not reliable to determine taphonomic signatures in single taxa assemblages (Kidwell et al 2001), LCE11 has not been considered for analysis.…”

Section: Survey Of Macrobenthosmentioning

confidence: 99%

Tafonomy of macroinvertebrates and Albian marine ingression as recorded by the Romualdo Formation (Cretaceous, Araripe Basin, Brazil)

2018

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“…Sin embargo, aún existen numerosos estudios tafonómicos que utilizan aproximaciones cualitativas, lo que dificulta la interpretación numérica, e incrementa la subjetividad de los resultados y, consecuentemente, reduce la replicabilidad de los trabajos. De la misma manera, la falta de una estandarización en la cuantificación ha dificultado la comparación y la generalizacion de los resultados (Kidwell et al, 2001;Kowalewski & Hoffmeister, 2003;Rothfus, 2004). Se puede reconocer una falta de estandarización en la recolección de las muestras, el esfuerzo de muestreo, la fracción granulométrica y el número mínimo de bioclastos para el análisis, así como en la definición de cuáles atributos tafonómicos son los más adecuados para el problema de interés y de qué manera cuantificarlos, de modo de permitir análisis estadísticos robustos y confiables.…”

Section: Introductionunclassified

“…Se puede reconocer una falta de estandarización en la recolección de las muestras, el esfuerzo de muestreo, la fracción granulométrica y el número mínimo de bioclastos para el análisis, así como en la definición de cuáles atributos tafonómicos son los más adecuados para el problema de interés y de qué manera cuantificarlos, de modo de permitir análisis estadísticos robustos y confiables. Esta falta de métodos objetivos y estandarizados ha limitado enormemente la posibilidad de comparación de los resultados entre diferentes estudios (Kidwell et al, 2001;Kowalewski & Hoffmeister, 2003;Rothfus, 2004;Rodrigues et al, 2009).…”

Section: Introductionunclassified

“…Diferentes operadores tienen distintas percepciones y el resultado final puede ser diferente aún para un mismo conjunto de datos. Esto ya fue demostrado tanto para la comparación entre dos operadores (Kidwell et al, 2001), como entre 13 operadores (Rothfus, 2004). Este efecto es lo que denominamos aquí como efecto del operador (también conocido como error inter-observador o error del observador).…”

Section: Introductionunclassified

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El sesgo del operador en la replicabilidad de los estudios tafonómicos comparativos

Ritter¹,

Francischini²,

Kuhn³

et al. 2017

Rev. bras. paleontol.

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OPERATOR BIAS AND REPLICABILITY IN COMPARATIVE TAPHONOMIC STUDIES. The operator effect is a well-known analytical bias already quantified in some taphonomic studies. However, the influence of operator bias in the replicability on taphonomic studies has still not been considered. Here, we quantified for the first time this bias using different multivariate statistical techniques, testing if the operator effect is related to the replicability. We analyzed the results reported by 15 operators working on the same dataset. Each operator analyzed 30 bioclasts (bivalve shells) by site, from a total of five sites, considering the following taphonomic attributes: shell fragmentation, edge rounding, corrasion, bioerosion, and color alteration. The operator effect followed the same pattern reported in previous studies, characterized by a worse correspondence for those attributes having more than two levels of damage categories. However, the effect did not appear to have relation to replicability, because nearly all operators found differences among sites. The binary attribute bioerosion exhibited 83% of correspondence among operators, but at the same time it was the taphonomic attribute that showed the highest dispersion among operators (28%). Therefore, we concluded that binary attributes, despite indicating a reduction of the operator effect diminishes replicability, resulting in different interpretations of concordant data. We found that a variance value of nearly 8% among operators was enough to generate a different taphonomic interpretation, in a Q-mode cluster analysis. The results reported here showed that the statistical method employed influences the level of replicability and comparability of a study and that the availability of results may be a valid alternative to reduce bias.

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Temporal dynamics of encrusting communities during the Late Devonian: a case study from the Central Devonian Field, Russia

Zatoń¹,

Borszcz

Rakociński³

2017

Paleobiology

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In this study we focused on the dynamics of encrusting assemblages preserved on brachiopod hosts collected from upper Frasnian and lower Famennian deposits of the Central Devonian Field, Russia. Because the encrusted brachiopods come from deposits bracketing the Frasnian/Famennian (F/F) boundary, the results also shed some light on ecological differences in encrusting communities before and after the Frasnian–Famennian (F-F) event. To explore the diversity dynamics of encrusting assemblages, we analyzed more than 1300 brachiopod valves (substrates) from two localities. Taxon accumulation plots and shareholder quorum subsampling (SQS) routines indicated that a reasonably small sample of brachiopod host valves (n=50) is sufficient to capture the majority of the encrusting genera recorded at a given site. The richness of encrusters per substrate declined simultaneously with the number of encrusting taxa in the lower Famennian, accompanied by a decrease in epibiont abundance, with a comparable decrease in mean encrustation intensity (percentage of bioclasts encrusted by one or more epibionts). Epibiont abundance and occupancy roughly mirror each other. Strikingly, few ecological characteristics are correlated with substrate size, possibly reflecting random settlement of larvae. Evenness, which is negatively correlated with substrate size, shows greater within-stage variability among samples than between Frasnian and Famennian intervals and may indicate the instability of early Famennian biocenoses following the faunal turnover. The occurrence distribution of encrusters points to nonrandom associations and exclusions among several encrusting taxa. However, abundance and occupancy of microconchids remained relatively stable throughout the sampled time interval. The notable decline in abundance (~60%) and relatively minor decline in diversity (~30%) suggest jointly that encrusting communities experienced ecological collapse rather than a major mass extinction event. The differences between the upper Frasnian and lower Famennian encrusting assemblages may thus record a turnover associated with the F-F event.

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Sensitivity of Taphonomic Signatures to Sample Size, Sieve Size, Damage Scoring System, and Target Taxa

Abstract: PALAIOS, 2001, V. 16, p. 26-52The sensitivity of taphonomic signatures to a battery of common sampling and analytic procedures is tested here using modern bivalve death assemblages from the San Blas Archipelago, Caribbean Panama, to determine (a)

Cited by 6 publications

References 14 publications

Tafonomy of macroinvertebrates and Albian marine ingression as recorded by the Romualdo Formation (Cretaceous, Araripe Basin, Brazil)

Tafonomy of macroinvertebrates and Albian marine ingression as recorded by the Romualdo Formation (Cretaceous, Araripe Basin, Brazil)

El sesgo del operador en la replicabilidad de los estudios tafonómicos comparativos

Temporal dynamics of encrusting communities during the Late Devonian: a case study from the Central Devonian Field, Russia

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