The Origin and Paleoecology of Clypeasteroid Assemblages From Different Shelf Settings of the Miocene of Sardinia, Italy

Mancosu, Andrea; Nebelsick, James H.

doi:10.2110/palo.2014.087

Cited by 18 publications

(5 citation statements)

References 56 publications

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“…On the basis of morphological features and comparison with recent analogues (see discussion in Mancosu and Nebelsick, 2015, 2016, 2017b), the Clypeaster olisiponensis morphotype, with a highly domed test with thick and tumid margins and flat oral surface, and the Clypeaster latirostris morphotype, with a lower test and relatively thin margin, are interpreted as epibenthic and semi- to shallow infaunal forms, respectively. These morphotypes occur frequently in the Miocene sedimentary deposits of shallow-water settings (see Mancosu and Nebelsick, 2015, 2016, 2017b and discussion therein). The Clypeaster marginatus morphotype with a low, flattened test and thin margins, is interpreted as a shallowly buried to partially burrowed form.…”

Section: Discussionmentioning

confidence: 91%

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Drilling predation on spatangoid echinoids from the Miocene of Sardinia: a taphonomic and paleoecological perspective

2022

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Predation is of great importance in understanding the diversification of spatangoid echinoids as well as their preservation in the fossil record. Herein, the spatangoid-dominated Miocene carbonate succession of Punta Foghe (Montiferru area, central-western Sardinia, Italy) is studied with the aim of reconstructing paleoenvironmental conditions and investigating abiotic and biotic factors, including predation, that influence the paleoecology and preservation potential of spatangoid echinoids. The echinoid fauna is dominated by the spatangoid Agassizia and, to a lesser extent, the clypeasteroid Clypeaster. The fauna also includes both regular (undetermined diadematoids and camarodonts) and irregular (Plagiobrissus, Echinocyamus, and Koehleraster) forms. Echinoids and associated fossil content, along with taphonomic and sedimentological signatures, indicate an inner sublittoral environment with moderate energy conditions affected by high-energy events. Agassizia remains, which consist mainly of complete and well-preserved tests, commonly bear subcircular drill holes that are interpreted as the result of cassid gastropod predation and investigated with respect to size selectivity and stereotypy of attack sites. Potential biases related to drilling predation and biostratinomy on the preservation potential of spatangoid tests are discussed. Agassizia lacks any morphological adaptation to minimize high predation risk, including defensive spines and the ability to burrow deeply into the sediment. An antipredator behavior possibly relied on a gregarious life-history strategy, reducing the frequency of attacks on specific individuals by cassid predators.

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Section: Discussionmentioning

confidence: 91%

“…The Clypeaster marginatus morphotype with a low, flattened test and thin margins, is interpreted as a shallowly buried to partially burrowed form. It is common as a minor component in spatangoid-dominated assemblages of moderately deep sublittoral environments (Mancosu and Nebelsick, 2015, 2017b, 2019).…”

Section: Discussionmentioning

confidence: 99%

Drilling predation on spatangoid echinoids from the Miocene of Sardinia: a taphonomic and paleoecological perspective

2022

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“…[17][18][19][20]). The skeletons of this echinoid group are common and often well-preserved in both recent environments and the fossil sedimentary record [11,[21][22][23][24][25][26][27][28], which is indicative for a structurally resilient skeletal architecture [20]. The minute Echinocyamus pusillus represents a particular case within the clypeasteroid echinoids as collagenous fibres between the plates are entirely absent [3].…”

Section: Introductionmentioning

confidence: 99%

Structural stress response of segmented natural shells: a numerical case study on the clypeasteroid echinoidEchinocyamus pusillus

Grun

Scheven

Bischoff

et al. 2018

J. R. Soc. Interface.

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The skeleton of Echinocyamus pusillus is considered as an exceptional model organism for structural strength and skeletal integrity within the echinoids as demonstrated by the absence of supportive collagenous fibres between single plates and the high preservation potential of their skeletons. The structural principles behind this remarkably stable, multi-plated, light-weight construction remain hardly explored. In this study, high-resolution X-ray micro-computed tomography, finite-element analysis and physical crushing tests are used to examine the structural mechanisms of this echinoid's skeleton. The virtual model of E. pusillus shows that the material is heterogeneously distributed with high material accumulations in the internal buttress system and at the plate boundaries. Finite-element analysis indicates that the heterogeneous material distribution has no effect on the skeleton's strength. This numerical approach also demonstrates that the internal buttress system is of high significance for the overall skeletal stability of this flattened echinoid. Results of the finite-element analyses with respect to the buttress importance were evaluated by physical crushing tests. These uniaxial compression experiments support the results of the simulation analysis. Additionally, the crushing tests demonstrate that organic tissues do not significantly contribute to the skeletal stability. The strength of the echinoid shell, hence, predominantly relies on the structural design.

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“…La replicabilidad de los métodos utilizados en Tafonomía es aún desconocida, aunque la utilización de atributos tafonómicos esté ampliamente reconocida en la actualidad (de forma no estandarizada) para diversos grupos de organismos, como los vertebrados (Araújo-Junior et al, 2015), equinoideos (Mancosu & Nebelsick, 2015), gasterópodos (Pisano et al, 2015), bivalvos (Erthal et al, 2015) y foraminíferos (Berkeley et al, 2009), entre otros.…”

Section: Introductionunclassified

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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The Origin and Paleoecology of Clypeasteroid Assemblages From Different Shelf Settings of the Miocene of Sardinia, Italy

Cited by 18 publications

References 56 publications

Drilling predation on spatangoid echinoids from the Miocene of Sardinia: a taphonomic and paleoecological perspective

Drilling predation on spatangoid echinoids from the Miocene of Sardinia: a taphonomic and paleoecological perspective

Structural stress response of segmented natural shells: a numerical case study on the clypeasteroid echinoidEchinocyamus pusillus

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

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