Exquisitely preserved embryo found inside fossilized dinosaur egg

Date:
December 21, 2021
Source:
University of Birmingham
Summary:
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.



FULL STORY ==========================================================================
A 72 to 66-million-year-old embryo found inside a fossilised dinosaur
egg sheds new light on the link between the behaviour 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 unrecognised in dinosaurs, this posture is similar to that of modern
bird embryos.

In modern birds, such postures are related to 'tucking' -- a behaviour controlled by the central nervous system and critical for hatching
success.

After studying egg and embryo, researchers believe that such pre-hatching behaviour, 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.

The embryo is articulated in its life position without much disruption
from fossilisation. 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 behaviours." '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.

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 behaviour, 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." ========================================================================== Story Source: Materials provided by University_of_Birmingham. Note:
Content may be edited for style and length.


========================================================================== Related Multimedia:
* Dinosaur_egg_and_embryo_reconstruction ========================================================================== Journal Reference:
1. Lida Xing, Kecheng Niu, Waisum Ma, Darla K. Zelenitsky, Tzu-Ruei
Yang,
Stephen L. Brusatte. An exquisitely preserved in-ovo theropod
dinosaur embryo sheds light on avian-like prehatching
postures. iScience, 2021; 103516 DOI: 10.1016/j.isci.2021.103516 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/12/211221133521.htm

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