Drilling gastropod predation on the lower Miocene gastropod assemblages from Kutch, western India: spatiotemporal implications

ABSTRACT

Unambiguous gastropod drilling predation has been reported in shells of Cretaceous age onwards. Global data suggest that the drilling intensity shows wide spatial variation throughout the Miocene. In order to understand the factors controlling geographic variability in drilling predation, data from many regions are needed. The present study includes detailed analyses of drilling intensity (DI) of predation, its spatial variability, and behavioural stereotypy within the lower Miocene gastropod assemblages of the two formations of Kutch, India. The studied area was positioned at about 17⁰N latitude during the lower Miocene. DIs calculated from 25,766 gastropod specimens in the assemblage, as well as at lower taxon levels, are relatively low for the entire lower Miocene. Prey effectiveness (PE) and Multiple drill holes (MULT) are also low. DI in each formation shows spatial variability which is not related to the number of samples per location and specimen numbers. Temporally, DI increases from the Aquitanian to the Burdigalian, and this rise is statistically significant. Low abundance of the predators and bivalves as a potential prey item are two possible causal factors for the low DI’s observed.

KEYWORDS:

• Drilling predation
• Miocene gastropods
• Kutch
• western India
• low predation
• spatial variability

Acknowledgments

Thanks are due to Subir Mukherjee, Jadavpur University for logistic support; all the members and summer interns of the Invertebrate Palaeontology laboratories (both Jadavpur University, Kolkata and Indian Statistical Institute, Kolkata). We also are grateful to Kanishka Bose for his help during photography. We are also thankful to Elizabeth Harper, Julieta Martinelli and Jansen Smith for critically reviewing an early version of the manuscript. PG and SB acknowledge the Department of Science and Technology (Project no. SR/S4/ES-638/2012) for partial funding. PG acknowledges Durgapur Government College for providing the infrastructural facilities. SSD and SB acknowledge Indian Statistical Institute and DST-SERB (Project no. EMR/2017/000328) for financial support and infrastructural facility. SP acknowledges the infrastructural facility provided by the IIT, Kharagpur. Patricia Kelley, Adiël Klompmaker and an anonymous reviewer critically reviewed the manuscript and provided valuable suggestions. Sriparna Saha and Shreya Adhvaryyu, two native English speakers have gone through the manuscript and provided many corrections in the English language. Thanks, are also due to Nigel Hughes, University of California Riverside who has critically read the manuscript and given valuable suggestions especially regarding the English language.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

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Additional information

Funding

This work was supported by the Indian Statistical Institute [5515C for the Year 2018–2019];Department of Science and Technology, Government of India [SR/S4/ES-638/2012,EMR/2017/000328,Inspire Faculty programme];Durgapur Government College.