Exquisitely Preserved Dinosaur Embryo Found Inside Fossilized Oviraptorosaur Egg

Oviraptorosaur Embryo Reconstruction

Life reconstruction of a close-to-hatching oviraptorosaur dinosaur embryo, based on the new specimen “Baby Yingliang.”
Credit: Lida Xing

A 72 to 66-million-year-old embryo found inside a fossilized dinosaur egg sheds new light on the link between the behavior of modern birds and dinosaurs, according to a new study.

The embryo, dubbed ‘Baby Yingliang’, was discovered in the Late Cretaceous rocks of Ganzhou, southern China, and belongs to a toothless theropod dinosaur, or oviraptorosaur. Among the most complete dinosaur embryos ever found, the fossil suggests that these dinosaurs developed bird-like postures close to hatching.

Scientists found the posture of ‘Baby Yingliang’ unique among known dinosaur embryos — its head lies below the body, with the feet on either side and the back curled along the blunt end of the egg. Previously unrecognized in dinosaurs, this posture is similar to that of modern bird embryos.

In modern birds, such postures are related to ‘tucking’ — a behavior controlled by the central nervous system and critical for hatching success. After studying egg and embryo, researchers believe that such pre-hatching behavior, previously considered unique to birds, may have originated among non-avian theropods.

Led by scientists from the University of Birmingham and China University of Geosciences (Beijing), the research team from institutions in China, UK, and Canada today published its findings in iScience.

Oviraptorosaur Embryo 'Baby Yingliang'

Photo of the oviraptorosaur embryo “Baby Yingliang.” Credit: Xing et al./iScience

The embryo is articulated in its life position without much disruption from fossilization. Estimated to be 27 cm long from head to tail, the creature lies inside a 17-cm-long elongatoolithid egg. The specimen is housed in Yingliang Stone Nature History Museum.

Fion Waisum Ma, joint first author and PhD researcher at the University of Birmingham, said: “Dinosaur embryos are some of the rarest fossils and most of them are incomplete with the bones dislocated. We are very excited about the discovery of ‘Baby Yingliang’ — it is preserved in a great condition and helps us answer a lot of questions about dinosaur growth and reproduction with it.

“It is interesting to see this dinosaur embryo and a chicken embryo pose in a similar way inside the egg, which possibly indicates similar prehatching behaviors.”

‘Baby Yingliang’ was identified as an oviraptorosaur based on its deep, toothless skull. Oviraptorosaurs are a group of feathered theropod dinosaurs, closely related to modern-day birds, known from the Cretaceous of Asia and North America. Their variable beak shapes and body sizes are likely to have allowed them to adopt a wide range of diets, including herbivory, omnivory, and carnivory. 


Animated life reconstruction of a close-to-hatching oviraptorosaur dinosaur embryo, based on the new specimen “Baby Yingliang.” Credit: Lida Xing

Birds are known to develop a series of tucking postures, in which they bend their body and bring their head under their wing, soon before hatching. Embryos that fail to attain such postures have a higher chance of death due to unsuccessful hatching.

By comparing ‘Baby Yingliang’ with the embryos of other theropods, long-necked sauropod dinosaurs and birds, the team proposed that tucking behavior, which was considered unique to birds, first evolved in theropod dinosaurs many tens or hundreds of millions of years ago. Additional discoveries of embryo fossils would be invaluable to further test this hypothesis.

Professor Lida Xing from China University of Geosciences (Beijing), joint first author of the study, said: “This dinosaur embryo was acquired by the director of Yingliang Group, Mr. Liang Liu, as suspected egg fossils around the 2000. During the construction of Yingliang Stone Nature History Museum in 2010s, museum staff sorted through the storage and discovered the specimens.

“These specimens were identified as dinosaur egg fossils. Fossil preparation was conducted and eventually unveiled the embryo hidden inside the egg. This is how ‘Baby Yingliang’ was brought to light.”

Professor Steve Brusatte from the University of Edinburgh, part of the research team, said: “This dinosaur embryo inside its egg is one of the most beautiful fossils I have ever seen. This little prenatal dinosaur looks just like a baby bird curled in its egg, which is yet more evidence that many features characteristic of today’s birds first evolved in their dinosaur ancestors.”

Reference: “An exquisitely preserved in-ovo theropod dinosaur embryo sheds light on avian-like prehatching postures” by Lida Xing, Kecheng Niu, Waisum Ma, Darla K. Zelenitsky, Tzu-Ruei Yang and Stephen L. Brusatte, 21 December 2021, iScience.
DOI: 10.1016/j.isci.2021.103516

6 Comments on "Exquisitely Preserved Dinosaur Embryo Found Inside Fossilized Oviraptorosaur Egg"

  1. Exquisitely preserved flightless bird embryo.oviraptor is not close to modern bird these primitive bird do not have a flight skull that why skull superfacial look like dinosaur these are archaeoteryx type of bird .this bird does not have unique antitrochanter Of dinosaur .even the first modern bird lack antitrochanter .modern bird antitrochanter have no link to dinosaur antitrochanter .sapaornis the ancestor of oviraptor they share unique primitive skull.sapaornis was a flying bird with a hypocleidum furcula . A None mesoeucrocodylia tetanuran eating plant?velociraptor killing prey with there feet it’s a bird .new fossil of none tetanuran that does that but it’s not a tetanuran this is because turtle link with the gator.oviraptor has advance hip not found in gator t.rex or any dinosaur.badit scientist if your right have a fair debate no corruption they are truth media out there and good scientist use all evidence hide by badit scientist have a debate with bandit scientist on YouTube with a scientist jury public is a jury we see if John Ruben will be fired .the real scientific world not the fake won that popular in the media .science is the truth only the answer the truth is the hype evidence evidence is evidence .scientist only want the answer .use all the evidence on internet the scientific world should be there.dinosaur is a thecodont animal thecodont mean crocodilian teeth .spinosauridae is a fully formed mesoeucrocodylia the death roll thecodont.

  2. Oviraptor bird was before archaeopteryx,archaeopteryx lack mandibular fenestra like modern bird .it’s mandibular fenestra primitive bird like Confuciusornis .confuciusornis had 3 mandibular fenestra main won is in middle like dinosaur the won they talk about dinosaur allso have small second won that no won talk about.archaeopteryx lost won they talk about .the first won not seen in dinosaur first allso found in oviraptor .microraptor allso has hypocleidum furcula a mandibular fenestra primitive bird.all maniraptoran oviraptor inner ear is like flying bird clearly show velociraptor oviraptor are flightless bird .archaeopteryx there is report that they have hypocleidum furcula I read it but badit scientist trying to change the result even if they do not have it there primitive ancestor had it prove archaeopteryx hypocleidum report was true .sapaornis sapeornis?I forgot to write this the femur of gator is unique to dinosaur not the bird like femur or coelophysis type s femur a new won I did some thing like this years ago about gator tibia .I did not look at it that much may be some day the femur.

  3. @coelophysis Dude, how high are you? Recommend backing off the cochise and striving for coherency.

  4. @coelophysis Dude, how high are you? Recommend backing off the *cocaine* and striving for coherency.

  5. Proper English please

  6. @coelophysis definitely had an A in science class. Pretty sure he flunked English though.

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