Image of the Titanosaur, Patagotitan, skeleton cast on display at the Field Museum of Natural History, Chicago (Pic: Courtesy Wikimedia Commons)
A significant yet to be published findings brings to light the discovery of fossil bone fragments off sauropod dinosaurs. Dating back to about 100 million years, these fragments have been discovered from an area around West Khasi Hills district in Meghalaya by a team of researchers from the Palaeontology division of the Geological Survey of India.
This is the first record of sauropods of probable Titanosaurian origin being discovered in the region, noted the researchers.
The physical attributes of the sauropods included very long necks, long tails, small heads relative to the rest of their body, and four thick, pillar-like legs. Sauropods were notable for the enormous sizes attained by some species, and this group included the largest animals to have ever lived on land.
With this finding in Meghalaya, it becomes the fifth India State after Gujarat, Madhya Pradesh, Maharashtra, and Tamil Nadu and the only State in the Northeast, to report Sauropod bones having titanosaurian affinity, observed the researchers.
Titanosaurs were a diverse group of sauropod dinosaurs, including genera from Africa, Asia, South America, North America, Europe, Australia and Antarctica.
As reported in a PTI despatch, Arindam Roy, Senior Geologist, Palaeontology Division said: “Dinosaur bones from Meghalaya were reported by GSI in 2001 but they were too fragmentary and ill-preserved to understand its taxonomic identification.”
Roy added that “The present find of bones is during fieldwork in 2019-2020 and 2020-21. The last visit of the team was in February 2021. The fossils are presumably of Late Cretaceous, about 100 million years ago.”
Talking about the fossils, Roy noted that the best-preserved fossils are limb bones, adding the type of curvature, development of lateral and proximal margins of the partially preserved bone are indicative of it being a humerus bone. However, he also observed that these conclusions are drawn from preliminary studies and detailed work is going on.
The bone fragments were collected from poorly sorted, purplish to greenish very coarse-grained arkosic sandstone interlaid with pebbly beds. The researchers disclosed that more than 25 disarticulated, mostly fragmentary bone specimens, which are of different sizes and occur as isolated specimens were recovered. Yet, some of them were found in close proximity to each other.
Pointing out that taxonomic identification up to genus level is difficult because of poorly preserved, incomplete, fragmentary nature of the bones, they said, most of the recovered bones are partially petrified and partially replaced.
Thus only three of the best-preserved ones could be studied. In this the largest one is a partially preserved limb bone of 55 centimetres long which is comparable with the average humerus length of titanosaurids.
According to the researchers, the robustness of the bone, the difference in curvature in the lateral margins and the proximal border being relatively straight, are some of the morphological characters that hint at the titanosaurid affinity.
Besides, this another incomplete limb bone measuring 45 cm in length is also comparable with the limb bones of titanosauriform clade.
Talking about the importance of this discovery, Roy remarked: “The abundance of bones recovered during the present work and especially the finding of few limb bones and vertebrae having taxonomic characters of titanosauriform clade are unique.”
He also noted that, “The record of the sauropod assemblage of probable titanosaurian affinity from Meghalaya extends the distribution and diversity of vertebrates in the Late Cretaceous of India.”
Talking about the other fragmentary specimens which are partially preserved, the team said, might probably be parts of limb bones of a sauropod dinosaur.
Elaborating on Titanosaurian sauropod dinosaurs, researchers said, they were the most diverse and abundant large-bodied terrestrial herbivores in the Southern Hemisphere landmasses during the Cretaceous Period but they were not endemic to the Gondwanan landmasses.
The Gondwanaland is the southern half of the Pangaean supercontinent that existed some 300 million years ago. It is composed of the major continental blocks of South America, Africa, Arabia, Madagascar, Sri Lanka, India, Antarctica, and Australia.
The researchers shared that In India, the Late Cretaceous sauropod dinosaur generally belongs to the titanosaurian clade and has been reported from the Lameta Formation of Gujarat, Madhya Pradesh and Maharashtra and Kallamedu Formation of Tamil Nadu.