Researchers from Delhi University have found 92 nests and 256 fossilised eggs belonging to titanosaurs, the largest dinosaurs to have ever lived, in central India, according to a new study.
Published last week in the journal PLOS One, the study, ‘New Late Cretaceous titanosaur sauropod dinosaur egg clutches from lower Narmada valley, India: Palaeobiology and taphonomy’, has been authored by Delhi University’s Dr Harsha Dhiman, Professor GVR Prasad and others.
As per the researchers, the study has focused on the newly found nesting sites in Dhar, Madhya Pradesh, where field investigations were conducted in December 2017, January 2018 and March 2020. Together with the previously found dinosaur nests in eastern MP’s Jabalpur, located in the upper Narmada Valley, and Gujarat’s Balasinor, situated in the west, the region constitutes one of the largest dinosaur hatcheries in the world.
The detailed examination of the discovered eggs and nests has shed light on how titanosaurs used to live. This includes details about their different species, reproductive systems, parental behaviour and colonial nesting behaviour.
Talking to The Indian Express, Prasad emphasised the necessity of studying fossilised eggs. He said, “The fossilised dinosaur eggs offer important palaeobiological information such as a number of dinosaur species (egg species), reproductive biology and nesting behaviour of egg laying dinosaurs.”
“Through geochemical work, important data related to the diet of the animal, environment and climate in which nests were deposited can be obtained.”
Findings of the study
During their research, the scientists identified six different “oospecies,” or egg species, that suggest a “possible high diversity in titanosaur taxa in the Indian subcontinent.” Previously found fossils of titanosaurs in India did not reflect this.
Apart from these oospecies, the team also found a pathologic ovum-in-ovo egg or a multi-shelled egg. They said it is the first time that such an egg has been found in the nests of titanosaurs. Usually, pathologic eggs are seen in birds only. Therefore, the discovery is a step forward in establishing similarities between the reproductive systems of reptiles and birds.
Prasad explained that it is well-known that titanosaurs had a similar nesting behaviour as today’s crocodiles. “However, a pathologic ovum-in-ovo egg (egg in egg) found during our study was known previously only in birds and never in any reptile including dinosaurs. This prompted us to suggest that the oviductal morphology of titanosaurs was more like that of birds”, he added.
The fossils were from the Late Cretaceous period and the researchers have identified six different “oospecies,” or egg species, which suggests a higher diversity of titanosaurs than can be inferred from skeletal remains from in the region. (Image credit: PLOS)
According to scientists, as the nesting sites are dotted with a number of closely spaced clutches — the total eggs a dinosaur laid per each nesting attempt — along with different kinds of eggs, they were able to conclude that the titanosaurs of this region adopted colonial nesting behaviour.
The closely spaced clutches also indicate that these dinosaurs didn’t prefer supervising their laid eggs.
“Since titanosaurs were huge animals they could not have revisited the nesting sites for manoeuvring the eggs or incubating the eggs like birds which would have resulted in overstepping and trampling of the eggs. Based on this, we concluded that parental supervision or care was not integral to their nesting behaviour”, Prasad said.
He also added that one of the reasons why fossils of titanosaurs, a herbivorous dinosaur, are commonly found in India is because they inhabited the Gondwanaland — a supercontinent that consisted of India, South America, Madagascar, Australia and Antarctica.
India’s tryst with dinosaurs
India has been a hotspot for finding dinosaur fossils for decades. The first time dinosaur bones were found was in 1822 by Capt William H Sleeman of the East India Company army. These bones were discovered near Jabalpur and belonged to a titanosaur. Since then, evidence of several other kinds of dinosaurs has been found in states such as Rajasthan, Gujarat, Andhra Pradesh, Maharashtra, Telangana, Karnataka and Tamil Nadu.
According to Prasad, around 17 different kinds of dinosaurs were present in the region, which is now known as India. Two different species existed during the Triassic period, about seven species during the Jurassic period and around eight species were here during the Cretaceous period.
Among them, one of the most famous dinosaurs in the country is Rajasaurus. Its fossils were first found by GSI geologist Suresh Srivastava in the 1980s. Teams from the American Institute of Indian Studies and the National Geographic Society, with the support of the Panjab University, spent years in order to reconstruct the excavated remains. In 2003, Rajasaurus was finally given its name by geologist Jeffrey A. Wilson, University of Michigan.
The discovery of Rajasaurus, a carnivorous dinosaur from the Cretaceous period, is also important because it is believed to be closely related to Majungatholus, a dinosaur from Madagascar. According to Prasad, the similarity between the two dinosaurs suggests that there was a terrestrial connection between India and Madagascar around 67 million years ago.
Titanosaurs, such as this Patagotitan (found in modern day South America), were the largest land animals ever to have evolved, yet we know very little about how they grew (Image: Wikimedia Commons) 
The fossils were from the Late Cretaceous period and the researchers have identified six different “oospecies,” or egg species, which suggests a higher diversity of titanosaurs than can be inferred from skeletal remains from in the region. (Image credit: PLOS)
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