With some species clocking in at the same size as today’s whales, titanosaurs were some of the largest dinosaurs to ever walk the Earth. These herbivorous sauropod dinosaurs, which lived from the Late Jurassic period (163.5 to 145 million years ago) to the end of the Cretaceous Period (145 to 66 million years ago), measured between 23 and 85 feet long. , depending on the species.
Now the discovery of these dinosaurs in one of their smallest forms is revealing intimate details about the lives of these gentle giants. In excavations between 2017 and 2020, a team of researchers discovered more than 250 fossilized eggs at 92 nesting sites in the Lameta Formation of central India. The findings are detailed in a study published Jan. 18 in the open access journal. PLUS ONE.
[Related: A fossilized egg laid by an extinct, human-sized turtle holds a rare jackpot.]
The Lameta Formation in the Narmada Valley is well known for fossils of dinosaur eggs and skeletons from the Late Cretaceous Period. Scientists first found dinosaur eggs in the region in the 1990s, and this study focuses on a nesting site in the Dhar district.
“Along with the Jabalpur dinosaur nests in the upper Narmada valley in the east and those at Balasinor in the west, the new nesting sites from the Dhar district of Madhya Pradesh (central India), which cover an east-west stretch about 1000 km [621 miles]they constitute one of the largest dinosaur breeding grounds in the world,” said Guntupalli VR Prasad, co-author of the study also from the University of Delhi, in a statement.
The team took a close look at the eggs, which were about six inches in diameter, and identified six different egg species, called oospecies. The variation suggests that there was a greater diversity of titanosaur species than currently represented by the fossilized skeletal remains found in this region.
“Our research has revealed the presence of an extensive roster of titanosaur sauropod dinosaurs in the study area and offers new insights into the nest preservation conditions and reproductive strategies of titanosaur sauropod dinosaurs just before they went extinct,” he said. Harsha Dhiman of the University of Delhi, the lead author of the study, in a statement.
The team also believes that titanosaurs buried their eggs in shallow pits similar to modern crocodiles based on the layout of the nests. They even found a rare case of an ovum in an egg (or egg-in-egg), indicating that titanosaur sauropods had similar reproductive physiology to modern birds and crocodiles and possibly laid their eggs sequentially.
Since many nests were found in the same area, the dinosaurs may have exhibited the colonial nesting behavior seen in modern-day birds, such as great egrets, brown pelicans, and cormorants. However, the narrow spacing between the nests did not leave much room for adult dinosaurs, supporting the idea that adult titanosaurs left their newborns to fend for themselves, unlike modern birds that sit on top of them. their eggs to incubate.
[Related: This newly discovered titanosaur had heart-shaped tail bones.]
Historically, the details of the reproductive habits of dinosaurs have been a bit difficult to pin down. Fossil nests can help, and the ones in this study offer insight into how some of history’s largest dinosaurs reproduced, evolved, and lived just before they went extinct.