After the fossil discovery from a cave in Meghalaya, the state has now reported finding the first ever dinosaurian teeth-fossils in the northeastern part of India.
Bashisha Iangrai and Vinod Kumar K. B. of Palaeontology Division, Geological Survey of India, the Northeast reported finding Titanosaurian Sauropod teeth from Mawphuli village near Ranikor, South West Khasi Hills District of Meghalaya.
Dinosaurs, the giant reptiles dominated the earth’s biosphere from about 225 million years up to 65 million years before the present Triassic, Jurassic and Cretaceous periods of the Mesozoic era in the geological timescale.
What are Titanosaurian Sauropods
Titanosaurian sauropods are the most diverse group of sauropod dinosaurs classified in the clade Titanosauria, which lived from the Late Jurassic Epoch (163.5 million to 145 million years ago) to the end of the Cretaceous Period (145 million to 66 million years ago). Titanosaur fossils have been found on all continents except Antarctica and include about 40 species. The group contains the largest terrestrial animals known, some even approaching the size of modern whales.
Sauropod, any member of the dinosaur subgroup Sauropoda, marked by large size, a long neck and tail, a four-legged stance, and a herbivorous diet. These reptiles were the largest of all dinosaurs and the largest land animals that ever lived.
Sinha & Mathur 1977 had the first-ever reported fragmented vertebrate bone fossils which were confirmed by Mishra & Sen in 2001 as Dinosaur bones from the upper part of the glauconitic sandstones of the Upper Cretaceous Mahadek Formation of Khasi Group near Nongnah, Meghalaya.
Later Maharana et al., 2006-07 & Iangrai & Dalabehera, 2021 reported the occurrence of several fragmentary and disarticulated Dinosaur bones from Dirang and Mawphuli, South West Khasi Hills of Meghalaya.
“This, however, is the first-ever reporting of dinosaurian teeth-fossils in the North-Eastern part of India. Earlier many workers have reported the occurrences of fragmentary and disarticulated Sauropod dinosaur bones from Meghalaya,” the GSI said.
Sauropod teeth from the Upper Cretaceous Mahadek Formation are exposed in Mawphuli village; where numerous fragmentary and broken vertebrate bones of Titanosaurian affinity are present. Two poorly preserved teeth were recovered from the coarse-grained, gritty, purplish arkosic sandstone of the Mahadek Formation, Khasi Group of Upper Cretaceous (Maastrichtian) age.
Although the complete tooth is not preserved; however, based on the morphology both teeth are comparable to the teeth of Sauropods of Titanosaurous of Late Cretaceous age as reported from the rest of the world.
In both the teeth, the apex and wear facets are missing and are of different sizes and shapes. The smaller tooth is chocolate brown in the crown portion and off-white in the base and is 16 mm long (Longitudinal axis) with a basal diameter of 5 mm. The mesiodistal diameter is 5.5 mm. The tooth has a distally straight crown without a well-developed root.
The Crown is slightly expanded above the root and has a blunt apex and longitudinal ridges on the labial and lingual sides, which lend a rhomboid outline to its cross-section. The apex is asymmetrical in labial/lingual view. The pulp cavity is narrow and filled with ferrous stains along the fissures at the base.
The cross-section of the base is semi-circular to circular with radiating structures. The enamel is very thin with a wrinkled texture at the base of the crown and has a thick dentine.
The bigger tooth is yellowish, 23 mm long and 20 mm wide and shows distinct crown-root transition and wrinkles on the thin enamel. The basal diameter is 18 mm and the cross section looks D-shaped/lemon-shaped. Carina (the lateral ridge) is also preserved. The enamel and dentine with pulp cavity are filled with purple-coloured sediments.
Both dinosaurian teeth specimens have similarities with the Titanosaurid Sauropod of the Late Cretaceous based on its size, shape and tooth morphology. Similar Titanosaurus teeth have been reported from the Anacleto and Allen formations of Argentina, the Kem Kem beds of Morocco, the Bissekty Formation of Uzbekistan and the Lower-Upper Cretaceous Winton Formation of Queensland, Australia.
In India, the Late Cretaceous Sauropod dinosaur belonging to the Titanosaurian clade has been reported from the Lameta Formation of Gujarat, Madhya Pradesh and Maharashtra, and the Kallamedu Formation of Tamil Nadu.
“This reporting of the Sauropod assemblage of Titanosaurian affinity from Meghalaya not only fills the gap in the stratigraphical record of Titanosaurids, but also allows a better understanding of the distribution and diversity of vertebrates in the Late Cretaceous formations of India,” the GSI said.
Also Read: Meet Bashisha Iangrai, a Meghalaya geologist and part of the ‘dinosaur discovery’ team