Just as the last Jurassic World movie was released in India a couple of days ago, a team of researchers from Delhi University (DU) has discovered an extremely rare dinosaur egg in Madhya Pradesh. DU has claimed that the find, an 'egg-in-egg' dinosaur egg or ovum-in-ovo egg, is the first-of-its-kind find in history and no other such fossil has been found for reptiles till date.

According to the team, the discovery is a "rare and important find". They said that the find could provide important insights into whether dinosaurs had reproductive biology similar to that of turtles and lizards, or crocodiles and birds, which are their immediate cousins. Their findings have been published in the latest issue of the Scientific Reports journal, reported PTI. The authors have documented that a large number of titanosaurian sauropod nests were found near Padlya village, which is close to Bagh town in Madhya Pradesh's Dhar district. And while studying these nests, the researchers came across one 'abnormal egg' among ten other eggs.

The abnormal egg had two continuous and circular eggshell layers separated by a wide gap reminiscent of ovum-in-ovo (one egg inside another egg) pathology of birds, according to a statement made by the researchers, as reported by PTI. "The microstructure of the pathological egg, as well as that of an adjacent egg in the same nest, identified it with that of titanosaurian sauropod dinosaurs. Until this find, no egg-in-egg abnormal fossil egg was found in dinosaurs and for that matter in other reptiles like turtles, lizards, and crocodiles," it stated further.

The Upper Cretaceous Lameta Formation of central India has been long known for the discovery of dinosaur fossils (both skeletal and egg remains). "The new find highlights the fact that central and western India hold great potential for dinosaur fossils which may offer important information on dinosaur species diversity, nesting behaviour and reproductive biology," the statement said. It further explained, "In the past, it was suggested that dinosaurs had a reproductive function similar to that of turtles and other reptiles, in contrast to the segmented reproductive tract of crocodiles and birds with separate regions of membrane and shell deposition." 

Although crocodiles have separate regions of shell membrane and mineralised shell deposition, they ovulate and release all the eggs simultaneously like turtles and other reptiles, as opposed to sequential ovulation of birds, which lay one egg at a time," it added, as reported by PTI. "The finding of ovum in ovo egg from a titanosaurian nest opens up the possibility that sauropod dinosaurs had an oviduct morphology similar to those of crocodiles or birds and they may have adapted to a mode of egg-laying characteristic of birds," said DU researcher Dr Harsha Dhiman, who is the lead author of the paper.

Professor Guntupalli V R Prasad, who is the corresponding author of the published article, concurred with his colleague, said, "The new pathological egg is a rare and important find as no ovum-in-ovo egg was found in reptiles until now and as it brings out significant information on whether dinosaurs had a reproductive biology similar to that of turtles and lizards or their immediate cousins, crocodiles and birds," as reported by PTI.