Sharks and rays (chondrichthyes, elasmobranchii) from the miocene sediments of Kutch, Gujarat, India: paleoenvironmental and paleobiogeographic implications

ABSTRACT

We report here a diverse assemblage of sharks and batoids representing the genera Carcharhinus, Rhizoprionodon, Galeocerdo, Sphyrna, Myliobatis, Aetobatus, Dasyatis, Pastinachus, Himantura and Pristis from Tapar and Jangadia the two late and early Miocene sites, respectively, of Kutch (Gujarat, India). The shark Rhizoprionodon and batoids, Dasyatis rugosa, D. cf. probsti, Dasyatis sp., Pastinachus and Himantura are being reported for the first time from the Miocene of western coast of India. The presence of Carcharhinus sp., Rhizoprionodon sp., Lamna sp., Negaprion sp., Sphyrna lewini, Myliobatis sp., Aetobatus sp. in the early Miocene Khari Nadi Formation exposed at Jangadia suggest existence of lagoonal, near shore to outer shelf environment. The rich batoid assemblage at the Late Miocene hominoid (Sivapithecus) bearing site of Tapar indicates the presence of a fresh to brackish water environmental condition. The faunal similarity of Miocene chondrichthyan of Indian Ocean and the Mediterranean Sea regions has been assessed using the beta diversity (Sørensen–Dice coefficient) data. The early Miocene elasmobranchs from Kutch shows close affinities with those from Mediterranean Sea. Similarly, in the Indian Ocean region Miocene fauna of Kutch shows close similarity with those of Baripada Beds, Orissa, Bhuban Formation of Mizoram, Gogha Coast, Piram Island and Madagascar.

KEYWORDS:

• Sharks
• batoids
• Kutch
• Miocene
• paleoenvironment
• paleobiogeography

Acknowledgments

KM Sharma is thankful to the Central university of Punjab Bathinda, India for the Research Seed Money Grant (Ref. no: CUPB/CC/16/00/13), UGC (No.F.30-4/2014 (BSR) and SERB (ECR/2016/001100) for the financial supports. NA Singh is thankful to UGC for providing JRF for pursuing Ph.D. R. Patnaik is thankful to SERB (HRR/2018/000063) for financial support. N. Amardas is thankful to UGC for providing JRF. The Authors are thankful to Prof. Sylvain Adnet (Institut des Sciences de l’Évolution Montpellier (ISEM), Université de Montpellier, France) for helping in identification of some of the specimens and for giving constructive suggestion on the draft manuscript. The authors are also thankful to Prof. M.G. Thakkar K.S.K.V. Kachchh University, India for his help during the field work. Encouragement and suggestions from Prof. Ashok Sahni (Panjab University, Chandigarh, India) are highly acknowledged. The authors are very thankful to all the anonymous reviewers for their valuable suggestions.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Research Seed Money, Central University of Punjab; [Ref. no: CUPB/CC/16/00/13]; Science and Engineering Research Board [ECR/2016/001100]; Science and Engineering Research Board [HRR/2018/000063].