Human-sized oviraptorid dinosaurs were born at different times like today’s birds, scientists say
Impressive fossilized dinosaur eggs found in China reveal that two-legged Oviraptorids hatch in the same way as today’s birds.
- Scientists fired neutrons against fossilized oviraptorid eggs to see their structure
- Bone structure and eggshell thickness revealed how they developed
- Dinosaurs developed at different speeds in their eggs, like today’s birds.
Three incredibly preserved dinosaur eggs found in China reveal the eggs of hatched oviraptorids similar to today’s birds.
The fossilized remains were studied by a team of German researchers who threw neutron rays at the embryos.
He revealed that two-legged dinosaurs are born at different times, placing them between birds and modern crocodiles in the evolutionary timeline.
Oviraptors lived in Central Asia during the Upper Cretaceous Period, about 88 million to 66 million years ago, and grew approximately the same size as humans.
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In the picture: the three oviraptorid eggs studied by scientists from the University of Bonn and the TU Munich
Artistic reconstruction of a group of eggs of oviraptóridos surrounded by the protective parents.
WHY NEUTRONS ARE USEFUL FOR SCIENTISTS?
Neutrons are particles in an atom that have a neutral charge.
They have a unique set of properties that make them ideal for investigating almost every type of matter.
Because the neutrons have no electrical charge, therefore, they do not interact with the electron layer of the atom, but with the atomic nuclei, or the center of the atom.
Therefore, neutrons are not destructive and can penetrate deeply into matter, which makes them an ideal probe for biological materials.
Neutrons can be used to study geological samples, new materials for energy production and storage, chemicals that affect the environment and polymers and plastics.
Scientists have assumed that they should be located somewhere between crocodiles and modern birds in terms of their reproductive biology.
But there had been uncertainty about whether oviraptorid chicks emerged from their eggs at the same time as their siblings, like today’s crocodiles, or were born at different times, like today’s birds.
Based on the internal thickness of the eggshells and the bone structure of the three 67 million-year-old egg fossils, the research team concluded that they were more similar to birds in this regard.
“This is different with the fossils we have examined: we found a couple of eggs and another egg together embedded in a block of rock,” said Dr. Tzu-Ruei Yang, co-author of the study, published in Organizational Integrative Biology.
The researchers concluded that the 7-inch (18 cm) eggs, which were taken from the Ganzhou basin in China, were laid almost simultaneously by a female oviraptoride.
By observing the length of the bones, the team calculated whether the three dinosaurs should hatch simultaneously or at different times depending on the stages of development of the embryos.
“The embryo with relatively longer bones is more developed,” said Yang.
Another indication of embryonic development is the extent to which the bones are connected to each other, with a more strongly connected skeleton that suggests more advanced development.
Photogrammetry of ‘egg 3, which was photographed and reconstructed from different perspectives.
Neutron tomography as a cross section through ‘egg 3’, which was one of two eggs laid later than the other
Based on observations of the length and position of the embryo’s bones, the researchers concluded that one egg must have been laid before the other two.
The developing embryo would also have absorbed calcium from the shell as it grew, to strengthen its developing skeleton.
Therefore, the thinner the shell, the more advanced the development of the embryo, and the older egg was compared with the other two.
The researchers summarized that the embryo of one egg was less developed than that of the other two “paired” eggs.
This showed that the eggs developed and hatched at different times despite being laid at the same time.
From this, the scientists concluded that the reproductive biology of oviraptors was more similar to that of modern birds than crocodiles.
Paleontologists at the University of Bonn in Germany initially tried to determine the position of the bones inside the ovules with the institute’s own X-ray microcomputer tomograph.
This technology shoots X-rays at a physical object to create a detailed 3D model, but it was not possible to distinguish the bones from the surrounding rock using only X-ray tomography.
Therefore, the team took the dinosaur eggs to the neutron research source of the Technical University of Munich at the Heinz Maier-Leibnitz Zentrum (MLZ) in Garching.
The high depth of penetration of the neurons allowed visualizing the detailed internal structures of the ovules.
The study has taken researchers one step closer to rebuilding the lives of extinct oviraptorids, which roamed Central Asia, including Mongolia and China, on two legs.
WHAT WERE THE OVIIRAPTORIDS?
The oviraptorids were a group of dinosaurs with thin limbs, clasped hands and a strange and distinctive skull.
Usually, they were about 3 feet to 6 feet long, about the size of a human.
Some of the best preserved dinosaur specimens that have been found are oviraptors.
Expeditions have found oviraptorid skeletons on top of the nests, suggesting that devout adults died in sudden sandstorms while protecting their nests.
Oviraptors lived in Central Asia during the Upper Cretaceous Period, about 88 million to 66 million years ago.
Source: University of Berkeley, California.