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Abstract <p>The mollusc fauna from the early Eocene Cambay Shale of the Cambay Basin, western India, has been described recently. A palaeoecological analysis of the stratigraphically changing composition, diversity, and abundance of this fauna was conducted in this study. The statistical tools employed here are the calculation of diversity indices, rarefaction analysis, testing rank-abundance models, and detrended correspondence analysis (DCA). The habits and habitat preferences of the members of the fauna have also been considered. A decrease in marginal-marine affiliated, herbivore taxa and an increase in eurytopic, carnivore forms from lower to upper levels, and an upward increase in marine influence as indicated by the DCA and analysis of habitat preferences of the mollusc genera support an onshore–offshore trend in the environmental evolution of the basin. The analyses indicate that the Cambay Shale, characterized by having an overall low specific mollusc diversity, several monospecific mollusc beds, and dominance of marginal-marine molluscs, was deposited in a quiet restricted coastal basin experiencing the early Eocene marine transgression. The basin experienced a relatively open marine environment later. An oyster bed at the top of the mollusc-bearing succession with no marine fossils above it indicates a regressive phase for the upper part of the Cambay Shale.</p> Research highlights <p><UnorderedList Mark="Bullet"> <ItemContent> <p>Changes in the composition, diversity-abundance pattern, trophic structure, and habitat preference of benthic molluscs in different levels are used to understand the palaeoenvironmental evolution of the Cambay Basin, western India, during the early Eocene.</p> </ItemContent> <ItemContent> <p>Tools such as diversity indices, rarefaction analysis, rank-abundance models, and detrended correspondence analysis (DCA) have been used for the reconstruction.</p> </ItemContent> <ItemContent> <p>The early Eocene hyperthermal and associated marine transgression events played important roles in the evolution of the basin and its faunal composition.</p> </ItemContent> </UnorderedList></p>

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Palaeoecological analysis of the early Eocene molluscs from Cambay Basin, western India, elucidates the evolution of the basin

  • 期刊论文

  • 发表日期：

    2025年8月20日

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  • Sayoni Banerjee,
  • Kalyan Halder,
  • Aniket Mitra

摘要

Abstract

The mollusc fauna from the early Eocene Cambay Shale of the Cambay Basin, western India, has been described recently. A palaeoecological analysis of the stratigraphically changing composition, diversity, and abundance of this fauna was conducted in this study. The statistical tools employed here are the calculation of diversity indices, rarefaction analysis, testing rank-abundance models, and detrended correspondence analysis (DCA). The habits and habitat preferences of the members of the fauna have also been considered. A decrease in marginal-marine affiliated, herbivore taxa and an increase in eurytopic, carnivore forms from lower to upper levels, and an upward increase in marine influence as indicated by the DCA and analysis of habitat preferences of the mollusc genera support an onshore–offshore trend in the environmental evolution of the basin. The analyses indicate that the Cambay Shale, characterized by having an overall low specific mollusc diversity, several monospecific mollusc beds, and dominance of marginal-marine molluscs, was deposited in a quiet restricted coastal basin experiencing the early Eocene marine transgression. The basin experienced a relatively open marine environment later. An oyster bed at the top of the mollusc-bearing succession with no marine fossils above it indicates a regressive phase for the upper part of the Cambay Shale.

Research highlights

Changes in the composition, diversity-abundance pattern, trophic structure, and habitat preference of benthic molluscs in different levels are used to understand the palaeoenvironmental evolution of the Cambay Basin, western India, during the early Eocene.

Tools such as diversity indices, rarefaction analysis, rank-abundance models, and detrended correspondence analysis (DCA) have been used for the reconstruction.

The early Eocene hyperthermal and associated marine transgression events played important roles in the evolution of the basin and its faunal composition.