The amazing discovery of a dinosaur embryo in a fossilized egg highlights the relationship of these ancient animals with birds

Dinosaur embryos are important to our understanding of how dinosaurs grow, yet very rare. While the remains of dinosaur embryos have occasionally been discovered in recent decades, most have been defective and their bones unhealthy; So the discovery of an almost healthy dinosaur embryo in an egg that is 72 to 66 million years old is amazing.

Based on the anatomy as well as the microscopic features of the eggshell, this small creature was identified as a member of the group of orapturosaurs (reptiles). Oyptorosaurs were a group of toothless dinosaurs of the tropoda branch that lived in Asia and North America during the Cretaceous.

The fossil was hidden from storage in Ganzhou, Jiangxi Province in southern China for 15 years until کچنگ نیو, The curator of the Yingliang Stone Museum of Natural History, discovered it in 2015. When he saw some broken bone on a piece of egg, he arranged for the fossil. This process involves removing the stone matrix around the bones and cleaning the fossil so that it can be studied. This revealed the complete skeleton of the fetus.

_{A close-up image of Ovirapturosaurus. The reconstruction is based on a new model called the Baby Yingliang.}

Realizing the scientific significance of this fossil, the museum invited a group of paleontologists to study it closely. In an article published in the journal iScience, the researchers reported the knowledge from Baby Yingliang.

The 27-centimeter-long Oyptorus embryo is in a position different from that seen in other dinosaur embryos. Its back is towards the wider end of the egg and its legs are on either side of the head. This condition is reminiscent of the fetus near the birth of modern birds. Egg contraction is a behavior that controls the central nervous system and is critical to the successful hatching of birds.

The position where the head is under the right wing and the body is gathered helps the bird to pull the eggshell with its tip on the day of birth. If a bird fails to reach this position, it will probably die due to its inability to hatch.

Baby Yingliang’s position is similar to that of a 17-day-old chicken embryo; That is, when it has not yet assembled the position. Finally, on the twentieth day, the chicken embryo assembles in order to prepare for the twenty-first day.

_{The ovaptorosaurus embryo, named Baby Yingluyang, provides rare insights into the prenatal behavior of non-flying dinosaurs.}

In addition, the researchers found similarities in the position of the previously reported oviportus embryo and the chicken embryo at about 14 days old. At this time, the chicken embryo is in the first stage of hatching. These observations suggest that the behavior inside the oviportosaur eggs may have been similar to that of modern birds before birth.

Egg-gathering behavior is often considered to be specific to birds; But by carefully comparing the embryonic positions of oraptorsors, including baby yingyling, as well as dinosaurs and other birds, researchers suggest that this behavior may have first evolved decades or hundreds of millions of years ago among theropod dinosaurs. This is further evidence that many of the characteristics of modern birds evolved in their dinosaur ancestors.

Behavior within dinosaur eggs is a subject rarely studied by paleontologists because of the scarcity of well-preserved healthy embryonic skeletons. The discoveries of Baby Yingliang and nearby embryos have allowed researchers to hypothesize for the first time what the behavior of ovaptorosaurus babies was before they hatched.

Researchers believe that more comprehensive comparisons of Baby Yingliang with the embryos of modern birds and crocodiles (the closest living relatives of dinosaurs), along with new fossil evidence, will enhance our understanding of the dinosaurs’ early growth and development.