New Delhi: A team of researchers discovered a 72 to 66 million-year-old embryo preserved inside a fossilised dinosaur egg. Scientists from the University of Birmingham and China University of Geosciences (Beijing) published their study regarding the embryo in the journal 'iScience'.
According to the study, the embryo belongs to a toothless theropod dinosaur or oviraptorosaur. Dubbed 'Baby Yingliang', the embryo was discovered in the Late Cretaceous rocks of Ganzhou, Southern China.
The fossil is one of the most complete dinosaur embryos ever found. It suggests that these dinosaurs developed bird-like postures close to hatching.
The discovery sheds light on the link between the behaviour of modern birds and dinosaurs, the study said.
Baby Yingliang Is Unique
The posture of 'Baby Yingliang' was unique among known dinosaur embryos, the study found. This is because, in the embryo, the head lies below the body, the feet are on either side, and the back is curled along the blunt end of the egg. The posture matches that of modern bird embryos and was previously unrecognised in dinosaurs.
Tucking, which is a behaviour found in modern birds, is controlled by the central nervous system and is critical for hatching success. According to the study, the posture observed in the fossilised embryo has similarities to the tucking behaviour.
This suggests that such pre-hatching behaviour may have originated from non-avian theropods.
Fossilisation has not disrupted the embryo, which has been maintained in its life position. The embryo is estimated to be 27 centimetres long from head to tail and lies inside a 17-cm long elongatoolithid egg. The unique fossil has been sent to the Yingliang Stone Nature History Museum.
Fion Waisum Ma, the joint first author of the study, said that dinosaur embryos are some of the rarest fossils and most of them are incomplete with the bones dislocated, according to a statement by the University of Birmingham. He added that the researchers were very excited about the discovery of 'Baby Yingliang' as it is preserved in great condition. Also, it helps scientists get answers to a lot of questions about dinosaur growth and reproduction, he explained.
He said that it is interesting to see the dinosaur embryo and a chicken embryo pose in a similar way inside the egg, which possibly indicates similar pre-hatching behaviours.
Baby Yingliang Has A Deep, Toothless Skull
Based on its deep, toothless skull, 'Baby Yingliang' was identified as an oviraptorosaur, the study said. Oviraptorosaurs are known from the Cretaceous period of Asia and North America and are feathered theropod dinosaurs, characterised by their variable beak shapes and body sizes.
When modern birds exhibit tucking behaviour, they bend their body and bring and head under their wing, soon before hatching.
The researchers proposed that tucking behaviour, which was considered unique to birds, first evolved theropod dinosaurs tens or hundreds of millions of years ago.