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Article Dans Une Revue Historical Biology Année : 2023

Coupling of taxonomic diversity and morphological disparity in Devonian trilobites?

Résumé

Morphological disparity and taxonomic richness are two major aspects of evolution used to understand biodiversity changes. These metrics are often decoupled in time, particularly during the early history of clades. To assess the pervasiveness of this pattern during the postacme of a clade, both morphological disparity and taxonomic diversity of the welldocumented Devonian trilobites from North Africa were analysed. Morphospace occupancy and body size were estimated and compared to genus richness through time. This study highlights that, during the Early Devonian, morphological disparity of the pygidium and the cephalon strongly increased, whereas cranidium disparity remained low. Interestingly, the pygidium and cephalon morphological dynamics were decoupled. Taxonomic diversity also increased. Then, the Middle Devonian anoxic events affected the trilobite communities with simultaneous drastic loss of both morphologies and taxonomic richness. This coupling in diversity and disparity dynamics could be explained by either the intensity of extinctions or strong internal constraints. Finally, the weak Famennian recovery of both disparity and diversity did not reach the Early Devonian levels, thus making trilobites a 'dead clade walking' during their late evolutionary history. Devonian trilobite families are thus identified as 'Top-Heavy Clades', characterized by a diversity peak at the end of their history.
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hal-04412702 , version 1 (23-01-2024)

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Paternité - Pas d'utilisation commerciale

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Valentin Bault, Catherine Crônier, Claude Monnet. Coupling of taxonomic diversity and morphological disparity in Devonian trilobites?. Historical Biology, 2023, pp.1-12. ⟨10.1080/08912963.2023.2167601⟩. ⟨hal-04412702⟩
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