Paleontologists working in India have discovered the first ever egg-in-egg dinosaur.
Also known as ovum-in-ovo, the egg was found in a dinosaur nest of titanosaurs dating back to the Lameta Formation of the Upper Cretaceous – about 66 million years to 100 million years ago.
This type of egg has only been observed in birds and occurs when an egg is pushed back into the mother’s reproductive system and embedded in another newly forming egg.
The team, led by the University of Delhi, believes this “rare and important” discovery shows dinosaurs shared reproductive biology similar to birds – dinosaurs were once thought to be more similar to turtles and other reptiles.
“We hypothesize that ovum in ovo pathology is not unique to birds and that sauropod dinosaurs had a reproductive anatomy more closely resembling that of archosaurs, such as crocodiles and birds, than non-archosaur reptiles, such as turtles.” and lizards. ‘ the team wrote in the study published in Scientific Reports.
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Paleontologists working in India have discovered the first ever egg-in-egg dinosaur. Also known as ovum-in-ovo, the egg was found in a dinosaur nest of titanosaurs dating back to the Lameta Formation of the Upper Cretaceous – about 66 million years to 100 million years ago.
The egg-in-egg was found in what experts dubbed “Nest P7,” which contained a total of eleven dinosaur eggs.
However, the team found a total of 52 nests in the area around the village of Padlya, near the town of Bagh.
All of the nests once belonged to titanosaurs, which were a diverse group of sauropod dinosaurs, including genera from all seven continents.
The titanosaurs were the last surviving group of long-necked sauropods, taxa still thriving at the time of the extinction event at the end of the Cretaceous.
The team found a total of 52 nests in the area around Padlya village, near the city of Bagh
The egg-in-egg was found in what experts dubbed “Nest P7,” which contained a total of 11 dinosaur eggs (pictured).
The extraordinary egg has two continuous and circular eggshell layers separated by a wide gap, and its fossilized remains make it clear that it is an egg within an egg.
“The cross-sectional view of the pathological egg shows a physical organization of the two shell layers, similar to ovum in ovo eggs previously reported in birds,” the study states.
“This raises the possibility that titanosaurs may have adapted to lay eggs sequentially.”
A separate dinosaur egg containing an exquisitely preserved embryo was discovered last year.
The embryo, dubbed “Baby Yingliang,” was found curled up inside the fossilized egg discovered in China.
And it’s about 66 to 72 million years old.
All of the nests once belonged to titanosaurs, which were a diverse group of sauropod dinosaurs, including genera from all seven continents
Paleontologists led by the University of Birmingham said that baby Yingliang belonged to a species of toothless beaked theropod dinosaurs, or “oviraptorosaurs.”
Oviraptors, which were feathered, are found in the rocks of Asia and North America and had different beaks and body sizes that allowed them to adopt a wide range of diets.
The specimen is one of the most complete dino embryos known and notably exhibits an attitude more similar to that of embryonic birds than is normally seen in dinosaurs.
Baby Yingliang, in particular, was about to hatch and had his head curled under his body, his back curled into the blunt end of the egg, and his feet positioned on either side of it.
In modern birds, such a posture is adopted during ‘feeding’ – a behavior of the embryo controlled by the central nervous system that is critical for successful hatching.
A separate dinosaur egg containing an exquisitely preserved embryo was discovered last year. The embryo, dubbed “Baby Yingliang,” was found curled up inside the fossilized egg discovered in China
The specimen is one of the most complete dino embryos known and notably exhibits an attitude more similar to that of embryonic birds than is normally seen in dinosaurs
The discovery of such behavior in Baby Yingliang suggests that this is not unique to birds but may have first evolved among non-avian theropod dinosaurs.
Fion Waisum Ma of the University of Birmingham said in a statement: “Dinosaur embryos are among the rarest fossils and most of them are incomplete as the bones are dislocated.
“We are very excited about the discovery of ‘Baby Yingliang’ – it is preserved in great condition and is helping us to answer many questions about dinosaur growth and reproduction.
“It is interesting to see that this dinosaur embryo and a chick embryo pose in a similar manner inside the egg, possibly indicating similar behavior before hatching.”
The researchers believe that the embryonic oviraptorosaur would have been about 27 cm long from head to tail, but developed curled up in a 17 cm long egg.