100-million-year-old dinosaur bones found in the Meghalaya, the region’s earliest record of sauropods
Researchers have identified fossil bone fragments of sauropod dinosaurs dating from around 100 million years ago in an area around the West Khasi Hills district in the Meghalaya. The findings that have yet to be published were made during a recent field visit by researchers from the paleontology division of the Geological Survey of India in the northeast. GSI researchers noted that this was the first record of sauropods of probable Titanosaurian origin found in the region. Sauropods had a very long neck, a long tail, a small head compared to the rest of their body, and four thick pillar-shaped legs. They are distinguished by the enormous sizes attained by some species, and the group includes the largest animals to ever live on earth. The discovery makes Meghalaya the fifth state in India after Gujarat, Madhya Pradesh, Maharashtra and Tamil Nadu and the only state in the northeast to report sauropod bones with titanosaur affinity, they said.
The Titanosaurs were a diverse group of sauropod dinosaurs, comprising genera from Africa, Asia, South America, North America, Europe, Australia, and Antarctica.
“Meghalaya dinosaur bones were reported by the GSI in 2001, but they were too fragmentary and poorly preserved to understand its taxonomic identification,” said Arindam Roy, senior geologist, Division of Paleontology, GSI.
“The present finding of bones takes place during fieldwork in 2019-2020 and 2020-21. The team’s last visit was in February 2021. The fossils probably date from the Late Cretaceous, around 100 million years ago, ”Roy told PTI.
He noted that the best-preserved fossils are the limb bones, adding that the type of curvature, development of the lateral and proximal margins of the partially preserved bone indicates that it is a humerus bone.
He noted, however, that the conclusions are drawn from preliminary studies and that detailed work is underway.
The bone fragments were collected in very coarse grained, poorly sorted, purplish to greenish arkosic sandstones interspersed with beds of pebbles.
Over twenty-five, mostly fragmentary, disarticulated bone specimens have been recovered, which are of varying sizes and appear as isolated specimens, but some of them have been found in close proximity to each other, the researchers said.
Taxonomic identification down to the genus level is difficult due to the poorly preserved, incomplete and fragmentary nature of the bones and most of the recovered bones are partially petrified and partially replaced, they said.
Therefore, only three of the best preserved could be studied. The largest is a partially preserved limb bone 55 centimeters (cm) long. It is comparable to the average length of the humerus of titanosaurids.
The robustness of the bone, the difference in curvature in the lateral margins and the proximal edge being relatively straight, are some of the morphological characters that suggest the affinity of titanosaurids, according to the researchers.
Another incomplete limb bone measuring 45cm in length is also comparable to member bones of the titanosauriform clade, they said.
“The abundance of bones recovered during the present work and in particular the discovery of some limb and vertebrae bones exhibiting taxonomic characters of the titanosauriform clade are unique,” said Roy.
“The record of the sauropod assemblage of probable affinity with the Meghalaya titanosaurs extends the distribution and diversity of vertebrates in the Late Cretaceous of India,” he noted.
An incomplete chevron of caudal vertebrae as well as cervical vertebrae were also reconstructed from a few recovered bone specimens.
The other fragmentary specimens, although partially preserved, could probably be parts of bones from limbs of a sauropod dinosaur.
The titanosaurian sauropod dinosaurs were the most diverse and abundant large terrestrial herbivores in the southern hemisphere landmasses during the Cretaceous Period, but they were not endemic to the Gondwana landmasses, the researchers said. .
Gondwanaland is the southern half of the Pangean supercontinent that existed around 300 million years ago and is made up of the main continental blocks of South America, Africa, Arabia, Madagascar, Sri Lanka, India, Antarctica and Australia.
In India, the Late Cretaceous sauropod dinosaur generally belongs to the titanosaurian clade and has been reported in the Lameta Formation of Gujarat, Madhya Pradesh and Maharashtra and the Kallamedu Formation in Tamil Nadu, the researchers said.
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