Dinosaur Fossils in the Thar Desert
In a paper published recently in Scientific Reports, scientists from IIT Roorkee have characterised dinosaur fossils from the Middle Jurassic period, found in the Thar desert near the Jaisalmer Basin by the Geological Survey of India.
They discovered that they had uncovered remains of a sauropod dinosaur, which is the same clade as the long-necked herbivores in Jurassic Park – only these happened to be the oldest known fossils of this particular kind of sauropod.
Belonging to the family Dicraeosauridae and from the superfamily Diplodocoidea, these fossils are the first dicraeosaurid sauropods to have been found in India.
And at 167 million years old, they are the oldest known diplodocoid fossils in the world.
The scientists named the dinosaur Tharosaurus indicus, with Tharo deriving from the Thar desert; saurus from the Greek ‘sauros’, or lizard; and indicus from its Indian origin.
The fossils were found by Triparna Ghosh, Pragya Pandey, and Krishna Kumar from the Geological Survey of India.
The most fascinating feature about sauropods is their size.
They can grow more than a hundred feet. There are many sauropod groups that are even longer than the blue whale.
However, members of the Dicraeosauridae family of sauropods – to which Tharasaurus belongs – were not nearly as large.
This family was unique: its members were smaller and had shorter necks and tails compared to the other long-necked sauropods.
Sauropods first appeared on the earth during the Jurassic period, about 200 million years ago.
They were one of the most dominant clades of dinosaurs, surviving until the late Cretaceous period 65 million years ago, when dinosaurs went extinct.
But strangely, in India, while sauropod fossils from the Early Jurassic and the Late Cretaceous period have been found.
very few have from the Middle or Late Jurassic period, which would be about 160-180 million years ago.
India has also been home to a few early, more primitive sauropods, like Kotasaurus and Barapasaurus.
They were both discovered in the Kota Formation, a geological rock unit in Telangana, from the Early Jurassic period.
Some 167 million years ago when Tharosaurus lived, India was not where it is now; it was part of a group of continents in the southern hemisphere with Africa, South America, Madagascar, and Antarctica, together called Gondwanaland.
The scientists reasoned that these diplodocoid sauropods could have originated in India during the Middle Jurassic period and used the land connections at the time to migrate to Madagascar, Africa, and South America.
After that they could have made their way to North America and the rest of the world.
Another piece of evidence that supports their theory was that diplodocoid fossils in other continents like Africa, the Americas, and Asia come from a younger geological interval.
This increases the possibility that the Indian landmass was the site for the Tharosaurus’ early radiation.
Archaic sauropod fossils from during the start of the Jurassic period –like of Kotasaurus and Barapasaurus – were also found in India suggests that this diplodocoid group of sauropods could have evolved and originated in India.
In 2006, an Indo-German team found another middle Jurassic sauropod dinosaur fossil in the Kutch basin of Gujarat, named Camarasaurus supremus, which was also the oldest fossil of that group found at the time.
There have been subsequent finds of extremely old sauropod fossils in the region by the same team since.
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