Scientists find dragonfly fossil, 2.5mn years old, in J’khand

Kolkata: A team of scientists from West Bengal has discovered the first dragonfly fossil found in India in Jharkhand’s Latehar district, according to a study published in Current Science. The fossil is said to be at least 2.5 million years old.

“This is the first dragonfly fossil from India. It is a well-preserved one. The fossil belongs to the late Neogene period which dates between 2.5 million and five million years ago,” said Subir Bera, a professor with the Centre for Advanced Study in the botany department of Calcutta University., and one of the authors of the study.

The study, published in the October 10 edition of the journal said the dragonfly fossil has a well-preserved head, thorax and a long cylindrical abdomen with terminalia (nether regions) and four wings with longitudinal veins, cross-veins and a characteristic small pterostigma (a pigment spot ) at the apex. The fossil is around 3 cm long and has a wing-span of around 2.5 cm. This is much smaller than the fossils of giant dragonflies, which have been found elsewhere in the world, the study said.

Experts said the wing-span of one of the giant dragonflies, Meganeuropsis permiana, measured around 2.5 feet; it was found by Frank Carpenter in Elmo, Kansas in the US in 1939. It dated back to the Permian era which made it around 300 million years old. In 2013, a giant, well preserved dragonfly fossil, dating back 200 million years, was discovered in China.

The researchers from four universities in West Bengal were looking for fossils in the sediments of the Chotanagpur plateau for almost a year when, in January, they found the dragonfly fossil at a depth of around 5m below the soil surface. The team also found fossils of various other insects, fish and flowering plants.

The study said the find suggested that this dragonfly thrived under a “tropical, warm, humid climate” during the depositional period and the fossil specimen was associated with prolific and diversified tropical angiospermic plant remains, vertebrates and invertebrates that provided a suitable environment for the dragonfly to survive.

“The nearest living member of the fossil is Libellula depressa, a species of dragonfly that is found in any tropical country including India,” said Manoshi Hazra, the first author of the research paper.

As dragonflies spend most of their lives near fresh water bodies, the scientists said that millions of years ago a freshwater body might have existed in the plateau, which has now dried up. The other fossils of plants and fish, which the scientists have found, also suggest so.

“The very fact that the team has found the fossil of an adult dragonfly from the sedimentary bed is very interesting. The prospect of finding an immature dragonfly from the sedimentary bed is huge because dragonfly larvae live underwater, and the prospect of finding insect fossils from sedimentary beds and coal beds is also huge, but unfortunately, little work has been done in India in this regard,” said TK Pal, a former scientist at the Zoological Survey of India.

According to the study, which was led by Mahasin Ali Khan, assistant professor of botany at Sidho-Kanho-Birsha University in West Bengal’s Purulia, dragonflies are known as “guardians of the watershed” and “wetland bio-indicators” and are carnivorous, feeding on other insects such as moths, flies, mosquitoes, bugs and midges.

“The presence of fossil flies, midges and butterflies in the fossil locality suggests that the dragonflies probably fed on these insects at that time. Thus, the late Neogene tropical forests of Jharkhand comprising abundant flora and fauna provided a suitable environment for the libellulid dragonfly to survive,” the study said.