It was a pleasant January winter morning last year and Ningthoujam Premjit Singh along with his team was out on their excavation work at Kutch. When he stumbled upon a premolar tooth of about 6 cm width and 7 cm length, little did he know that what he held belonged to an extinct ancient elephant called Deinotherium indicum.
First occurrence
Interestingly, this turned out to be the region’s first occurrence of the mammal which weighed between eight and 10 tons in weight. Dr. Singh adds that this new find also expands the distribution range of this species, hitherto only known from two or three localities (Tapar of Gujarat, Haritalyangar in Himachal Pradesh, and Piram Island off the coast of Gujarat). It also increases our understanding of the variations in dental morphology of the South Asian Deinotheres species. Dr. Singh is a postdoctoral fellow at the Department of Geology at Panjab University and the first author of the paper recently published in the Journal of Paleontology.
Biostratigraphy
Using a technique called biostratigraphy, it was noted that D. indicum lived roughly between 11 and 7 seven million years ago in India. In biostratigraphy, the presence of certain species from a known time period can be used to estimate the age of a deposit containing the same species in a different locality. “Remains of D. indicum have been found in well-dated Siwalik deposits from Haritalyangar of Himachal Pradesh. Based on the similarity in species, we inferred a similar date for the Kutch’s D. indicum ,” Advait M. Jukar from the Department of Paleobiology, National Museum of Natural History, Smithsonian Institution explains in an email to The Hindu . He is the co-first author and corresponding author of the paper.
He adds that definite dates can only be procured when paleomagnetic and radiometric studies are performed on the rocks that these fossils came from.
When asked how morphologically different this species is from today's elephants, he explained that though they had similar large bodies with column-like limbs, their heads were very different. “They had flatter skulls, and a set of downwards pointing, curved tusks only on the lower jaw. Analyses of their skulls have shown that they probably also had a short, slightly bulbous trunk. If you looked inside their mouths, all of their teeth would have erupted and were used in chewing at the same time. Modern elephants have only one tooth in use on each side of their jaw,” explains Dr. Jukar.
Distant relative
This species was a fairly distant relative of today’s elephants, both evolutionarily and in time. The deinotheriidae, the family that includes D. indicum, was first found in the fossil record approximately 28 million years old in Africa, but the family that includes modern elephants doesn’t appear until about eight million years ago.
The team plans to continue their studies in the Tapar beds of Kutch as it may be hiding many more fossils. “The plan now is to keep describing different species until we have a solid understanding of the diversity of vertebrates from western India. We hope to create a dataset of species occurrences through time in western India and compare the trends in diversity seen there with those seen in the well-studied fossil record from the Siwaliks,” adds Dr. Jukar.
