The new ichnospecies Teredolites solitarius and its taphonomy from the Cenozoic carbonate intervals of Kutch Basin, India

Abstract

Teredinidae is a family of bivalves occupying a spatial range of brackish to open-marine benthic niches and a stratigraphic range from Jurassic to recent. The teredinid genus Kuphus occurs within the calcareous muddy stiffground to hardground as vertical to inclined calcareous tubes. The ichnogenera Teredolites and Apectoichnus encompass the borings generally produced by the teredinids/shipworms. In the Kutch Basin, solitary teredinid borings range from the Eocene to the Early Miocene. Each subvertical boring has a calcareous wall with growth annulations on its outer surface. These tubes do not display any homeomorphic exoskeletal character. Rather, they manifest the producer’s ethology of mechanical boring into the organic-rich stiffground to hardground substrates and sustenance through microbially mediated chemosymbiosis. A systematic ichnotaxonomy is presented here for the solitary ‘Kuphus tubes’ which are classified as a new ichnospecies: Teredolites solitarius. The taphonomic analysis of the borings is based on the size, shape, orientation, and composite secondary borings, which are used in ascertaining the depositional conditions and palaeoecology. Two distinct taphofacies, i.e. TS-A and TS-B, have been identified. The TS-A represents the in-situ vertical morphotype formed in a restricted intermittently brackish mud-dominated inner carbonate ramp setting. The TS-B represents the reworked borings redeposited along with other bioclasts in a storm-influenced lower to middle shoreface setting.

Keywords:

• Shipworm
• Teredolites
• bioerosion
• boring
• Kuphus
• Kachchh Basin

Acknowledgements

The authors extend their sincere gratitude to the following funding organizations for the research grants: Science and Engineering Research Board (SERB), Government of India (grant # CRG/2018/000259 to SDG), Industrial Research and Consultancy Centre (IRCC), IIT Bombay (seed grant # RD/0517-IRCCSH0-035 to SDG), Council of Scientific & Industrial Research (CSIR) (doctoral scholarship for AS and RD), IITB and Ministry of Education of India (doctoral scholarship for MD). We express our sincere gratitude to Dr. Umesh Kumar, Head of the IT&I Section at Bhabha Atomic Research Centre (BARC), Government of India, Mumbai, for his invaluable support in facilitating access to the X-Ray CT scanning facility. A special appreciation is extended to Rajesh Acharya, Scientific Officer, IT&I Section, BARC, and Lakshminarayana, as well as, to Anant Mitra, for their unwavering support and enriching discussions. The authors are grateful for the time and dedication shown by both the Editors (LA Buatois and MK Gingras), Associate Editor (RG Netto), and anonymous reviewers #1 and #2 in providing their valuable and insightful critical feedback to enhance the quality of our paper. Heartfelt appreciation goes to PK Saraswati, MG Mángano, S Banerjee, J Punekar, and P Kumar, for their invaluable input and discussions. The authors hold high regard for the assistance received from Indian Railways, the State Government of Gujarat, and the District Administration of Kachchh. The authors express profound gratitude to the Department of Earth Sciences and SAIF (Sophisticated Analytical Instrumentation Facility), IIT Bombay, for their support in providing essential infrastructure. We express our sincere appreciation to K Prasad for offering invaluable insights into the Oligocene MFF. Additionally, we extend our appreciation to A Natarajan for his help in handling the CT data. The commendable contributions of D Rajkhowa and K Chatterjee in the fieldwork and sample collection are duly acknowledged. Their collective efforts have enriched this study, and we acknowledge their dedication and expertise in enhancing the quality of our research.

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No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by Industrial Research and Consultancy Centre, IIT Bombay.