At the Dinosaur Fossil National Park in Madhya Pradesh’s Dhar district, a team of researchers from the University of Delhi discovered a unique set of fossilized dinosaur eggs, one nesting within the other. While eggs-within-eggs are a rare occurrence, they have only been observed in birds and have never been observed in reptiles. This finding reveals newer links between reptilian and avian evolution.
The findings, which were published in the journal Scientific Reports, discuss the “egg-in-egg” phenomenon in a titanosaurid dinosaur egg discovered in the Bagh area of Madhya Pradesh’s Dhar district.
Sauropod dinosaurs were among the largest land animals
Sauropod dinosaurs were among the largest land animals ever to exist, and they have widely distributed millions of years ago in what is now India. These animals’ fossils have been discovered in Gujarat, Madhya Pradesh, and Meghalaya.
The Upper Cretaceous Lameta Formation of Central India has long been known for its dinosaur fossils (both skeletal and egg remains), and scientists in Madhya Pradesh documented 52 titanosaurid sauropod nests near Padlya village, close to Bagh town.
One of these nests contained ten eggs
One of these nests contained ten eggs, one of which was “abnormal.” The egg has two circular eggshell layers that are separated by a wide gap, similar to that seen in birds. Until now, no egg-in-egg fossil egg had been discovered in dinosaurs or other reptiles like turtles, lizards, or crocodiles.
Dinosaurs were thought to have a reproductive function similar to that of turtles and other reptiles (unsegmented oviduct), as opposed to crocodiles and birds, which have a segmented reproductive tract with separate membrane and shell deposition regions.
Crocodiles, like turtles and other reptiles, have separate regions of shell membrane and mineralized shell deposition, but they ovulate and release all of their eggs at the same time. Ovulation in birds is timed, and eggs are laid one at a time. “The new discovery of an ovum-in-ovum egg in titanosaurids is for a segmented oviduct like in crocodiles and birds, and possible sequential laying of eggs like in birds,” the authors speculate.
The discovery of an ovum-in-ovo egg from a titanosaurid nest
“The discovery of an ovum-in-ovo egg from a titanosaurid nest raises the possibility that sauropod dinosaurs had oviduct morphology similar to that of crocodiles or birds, and they may have adapted to a mode of egg-laying similar to birds,” said Harsha Dhiman, Department of Geology, University of Delhi, and study lead author.
“The new pathological egg is a rare and important find because no ovum-in-ovo egg has been found in reptiles before now,” said Prof. Guntupalli V.R. Prasad of the University of Delhi, who is also the corresponding author of the published article. “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.”
Vishal Verma, a co-author of the paper who works in fossil site conservation and was instrumental in the establishment of four local museums, said that the “Bagh-Kukshi area holds key to many such wonderful fossil finds provided systematic scientific exploration is carried out as in the present case.”
Central and Western India are rich in dinosaur fossils
The new discovery emphasizes the fact that Central and Western India are rich in dinosaur fossils, which could provide valuable information on dinosaur diversity, nesting behaviour, and reproductive biology, according to the authors.
At the Dinosaur Fossil National Park in Madhya Pradesh’s Dhar district, a team of researchers from the University of Delhi discovered a unique set of fossilized dinosaur eggs, one nesting within the other. The findings, which were published in the journal Scientific Reports, discuss the “egg-in-egg” phenomenon in a titanosaurid dinosaur egg discovered in the Bagh area of Madhya Pradesh’s Dhar district.