Egg discovery sheds light on titanosaur nesting pattern

Indian dinosaur hunters on Wednesday reported the discovery of more than 250 fossilised eggs from central India, revealing intimate details about the lives of titanosaurs — one of the largest long-neck plant-eating dinosaurs that have ever roamed the Earth.

A team led by Delhi University researchers identified six different egg species, suggesting a higher diversity of titanosaurs than is represented by skeletal remains from this region.

Based on the layout of the nests, they inferred that these dinosaurs buried their eggs in shallow pits like modern-day crocodiles.

Certain pathologies found in the eggs, such as a rare case of an “egg-in-egg”, indicate that titanosaur sauropods had a reproductive physiology that parallels that of birds and possibly laid their eggs in a sequential manner as seen in modern birds.

The presence of many nests in the same area suggests these dinosaurs exhibited colonial nesting behaviour like many modern birds. But the close spacing of the nests left little room for adult dinosaurs, supporting the idea that adults left the hatchlings (newborns) to fend for themselves.

The fossilised eggs were found in a distinct type of geological site (Lameta Formation), in the Narmada valley in MP. The area is well-known for fossils of dinosaur skeletons and eggs of the Late Cretaceous Period (between 100-66 million years ago). The researchers found 92 nesting sites containing 256 fossil eggs belonging to titanosaurs.

“Together with dinosaur nests from Jabalpur in the upper Narmada valley in the east and those from Balasinor in the west, the new nesting sites from Dhar district in MP, covering an east-west stretch of about 1,000 km, constitute one of the largest dinosaur hatcheries in the world,” said Guntupalli VR Prasad, team leader from DU.

Since details of dinosaur reproductive habits can be difficult to determine, a detailed examination of these nests has allowed Dhiman and colleagues from IISER Bhopal and Kolkata among others to make inferences about life habits of these dinosaurs. The study has appeared in the journal PLOS One.

Last year, the DU team reported discovery of one abnormal egg from a site close to Bagh town in Dhar. The abnormal egg displays two continuous and circular eggshell layers separated by a wide gap reminiscent of ovum-in-ovo (one egg inside another egg) pathology of birds.

Until such a find from India, no egg-in-egg abnormal fossil egg was found in dinosaurs. The discovery opened up the possibility that sauropod dinosaurs had an oviduct morphology similar to those of crocodiles or birds and they might have adapted to a mode of egg-laying characteristic of birds.

Vishal Verma, one of the coauthors from Bakaner Higher Secondary School and a campaigner for the conservation of fossil sites said, “Bagh-Kukshi area holds the key to many such wonderful fossil finds provided systematic scientific exploration is carried out."