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115-million-year old shark fossils discovered in Jaisalmer: Research

ByDinesh Bothra I Edited by Shilpa Ambardar, Jodhpur
Nov 30, 2023 06:58 PM IST

According to the researchers, the Early Cretaceous was a period of great change for sharks, as new species evolved and old ones disappeared

A team of researchers have discovered India’s first Early Cretaceous shark fossils, “which are 115-million year old” in Jaisalmer area of Rajasthan, according to a research paper. The research paper, “First Early Cretaceous Sharks from India,” was published in Historical Biology, An International Journal of Paleobiology on November 18.

The fossils discovered from the Habur Formation of Jaisalmer Basin in Rajasthan sheds light on a small assemblage of Early Cretaceous (Aptian) sharks (Pic Courtesy: Researchers)
The fossils discovered from the Habur Formation of Jaisalmer Basin in Rajasthan sheds light on a small assemblage of Early Cretaceous (Aptian) sharks (Pic Courtesy: Researchers)

The team of researcher included Triparna Ghosh from the Geological Survey of India (GSI), Jaipur; professor Sunil Bajpai from the Department of Earth Sciences at Indian Institute of Technology (IIT) Roorkee; Krishna Kumar from GSI, Kolkata; Abhayanand Singh Maurya from IIT, and Debasish Bhattacharya from GSI, Kolkata.

According to the researchers, the Early Cretaceous was a period of great change for sharks, as new species evolved and old ones disappeared.

The fossils discovered from the Habur Formation of Jaisalmer Basin in Rajasthan sheds light on a small assemblage of Early Cretaceous (Aptian) sharks.

Researchers said, “The Habur Formation consists of multiple layers, including brown coloured, hard, sandy coquinoidal limestone and orange to brown calcareous sandstone in the lower part and yellowish arenaceous limestone, calcareous sandstone and sandy marl bands in the upper part.The Habur Formation represents a near shore environment with occasional storm events as evident from ammonite beds intercalated with arenaceous limestone and calcareous sandstone.”

The findings, primarily based on isolated teeth, reveal the presence of five lamniform genera —Cretalamna, Dwardius, Leptostyrax, Squalicorax, and Eostriatolamia. These are all genera of large, predatory sharks with serrated teeth that lived during the Cretaceous period, according to the researchers.

Professor Bajpai emphasized the paleobiogeographical significance of the discovery, stating that “the records of Dwardius and Eostriatolamia may possibly be among the globally oldest, with the fossils being an astonishing 115-million-year old”.

These are all genera of large, predatory sharks with serrated teeth that lived during the Cretaceous period, said the researchers.

“Compared to their Late Cretaceous counterparts, our knowledge of Early Cretaceous vertebrates in India is scant, with only a few records,” professor Bajpai said.

Stressing upon the importance of this discovery, he added: “Previously Mesozoic lamniform sharks reported from India included Cretalamna appendiculata, Dwardius sudindicus, Squalicorax aff. Baharijensis, Eostriatolamia sp. and Cretodus longiplicatus from the Cenomanian Karai Formation of Cauvery Basin, southern India.” However, the present study introduces new dimensions, unveiling the first Early Cretaceous lamniform sharks in India, he added.

The fossils, extracted from the Habur Formation near Kanoi village in Jaisalmer, include isolated neoselachian teeth, said the professor. Sharing details about the nature of the study, he said:“wherever possible, these teeth were extracted from the matrix and prepared using mechanical means including a pneumatic air scribe”.

The collection is now housed in the Palaeontology division of the Geological Survey of India, Western Region, Jaipur. The specimens, dating back to the Aptian age and 115-million-year old, represent one of the oldest records of the genus Cretalamna globally, underlining the credibility and significance of the findings, according to the researchers.

The researchers’ team not only documented the presence of five lamniform genera but also underscored the scarcity of prior knowledge regarding Early Cretaceous sharks in India, said the paper.“The significance of the discovery lies in the fact that it introduces Leptostyrax as a first-time record from the Indian subcontinent, and Dwardius, if identified correctly, may represent the oldest known records of its genus globally,” said the researchers. Bajpai said that “this discovery is significant as it opens up new possibilities for collection and study of Early Cretaceous vertebrates from India.”

The study suggests that the Habur assemblage’s paleobiogeographic significance will become more apparent with additional material and species-level identification, adding credibility to the unfolding narrative of India’s ancient marine life.

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