Fossils of 167-million-year-old dinosaur are the oldest of its kind

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Dicraeosaurids were a family of small-bodied sauropod dinosaurs that diversified from the Middle Jurassic to the Lower Cretaceous. Their most distinctive features were their long spine and unusual walking. They also ate plants.

Mostly found in Africa and South America, besides a few occurrences in the USA and China, to date, no diplodocoid (a broader group encompassing the dicraeosaurids) sauropods have been traced in India. Until now.

A team of researchers from India has discovered fossils of a new dicraeosaurid from the Indian city of Jaisalmer in western India. These fossils, dating back to 167 million years, include bones separated at the joints but associated with specimens of the central body bones spread over an area of 270 square feet ( 25- square meters).

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The dicraeosaurid, called Tharosaurus Indicus in reference to the Thar desert where the fossils were found, is the first ever discovered in India and the oldest in the world’s fossil record.

Fossils of 167-million-year-old dinosaur are the oldest of its kind — Caudal vertebrae of Tharosaurus indicus
Bajpai et al

"The significance of this discovery rests in its antiquity," said Sunil Bajpai, a vertebrate paleontologist at the Indian Institute of Technology Roorkee and an author of the study, in an interview with Economic Times.

The team of five began their work in 2018 when they discovered these fossils. The team acknowledged that the material in their possession is fragmentary, and there is a possibility that as more evidence is recovered, there might be a change in their taxonomic attribution; the fact remains that Tharosaurus Indicus currently is the oldest known diplodocoid.

“...the discovery of Tharosaurus makes India a major center for not only diplodocoid but neosauropod radiation,” said the authors in the study. The discovery of Tharosaurus suggests that India played a significant role in the emergence and diversification of neosauropods, a group of long-necked vegetarian dinosaurs that thrived as the largest land animals, explained Debajit Datta, co-author of the study, in an interview with The New York Times.

More research work needed

The discovery of the oldest plant-eating dinosaur to have walked on the Earth provides critical insights into sauropod diversity in the Indian Gondwana, with important implications for the origin and dispersal of Neosauropoda.

In the eastern Gondwana, non-neosauropods could be found in India, New Zealand, and parts of Thailand, Germany, and China during the Late Triassic–Early Jurassic. The researchers think that early ancestors of Neosauropods appeared and radiated during the late Early or early Middle Jurassic in Asia and North–South America.

Dr. Bajpai told NYT that India has a rich repository of dinosaur fossils, but a lack of vertebrate paleontologists limits their discovery. Due to mining operations, lack of funding, and unemployment, paleontology is not advancing in the country.

The study was published in the peer-reviewed open-access journal Scientific Reports.

Study abstract:

The Early Jurassic and Cretaceous deposits of India are known for their diverse sauropod fauna, while little is known from the Middle and Late Jurassic. Here we report the first ever remains of a dicraeosaurid sauropod from India, Tharosaurus indicus gen. et sp. nov., from the Middle Jurassic (early–middle Bathonian) strata of Jaisalmer Basin, western India. Known from elements of the axial skeleton, the new taxon is phylogenetically among the earlier-diverging dicraeosaurids, and its stratigraphic age makes it the earliest known diplodocoid globally. Palaeobiogeographic considerations of Tharosaurus, seen in conjunction with the other Indian Jurassic sauropods, suggest that the new Indian taxon is a relic of a lineage that originated in India and underwent rapid dispersal across the rest of Pangaea. Here we emphasize the importance of Gondwanan India in tracing the origin and early evolutionary history of neosauropod dinosaurs.