Egg hatching diagram of a stealing dragon. Zhao Chuang draws
A scan of the egg of the ovule dragon egg can see the embryos at different stages of development. Courtesy of Bi Shundong
A few days ago, paleontologists cracked a century-old "unsolved case": the dinosaur named "egg stealing dragon" did not make a living by "stealing eggs", and did not have the habit of being a "thief" for generations, but a loving dinosaur that "mother laid eggs and father hatched".
The origin of the name "stealing eggs"
In 1923, the Mongolian Gobi Desert. American explorer Roy Chapman Andrews discovered a nest buried under a sand dune and fossilized dinosaur eggs.
Next to this nest, there is a theropod dinosaur fossil with its head next to the nest's dinosaur egg. The expedition believed that the dinosaur must have been buried by a sudden sandstorm while preparing to steal eggs, or trampled to death by other dinosaurs passing by.
After studying the fossil, paleontologists gave the dinosaur a very disgraceful name, Oviraptorosaurus.
At that time, the expedition also found a variety of dinosaur fossils such as protocera and apatosaurus. Because protocerapidosaurs are common in the Mongolian desert, researchers are paranoid that the owner of this nest of eggs is protoceratops, and it is the "thief" who dies next to the nest.
Egg stealing seems to be conclusive evidence, oviraptorosaurs were thus declared guilty of "stealing", not only the family category was named "oviraptorosaurs" by the academic community, the species found at that time was also named "oviraptorosaurs who loved protocephras", Chinese translated as "horned oviraptorosaurs".
After being misunderstood, the researchers tried to find evidence of the "original sin" of egg stealing from the body structure of the egg stealing dragon. As a result, the oviraptorosaur's flexible claws, slender fingers, and hard convex mouth were considered to be suitable "crime tools" for egg holding and pecking eggs.
Scientific research also steals the "innocence" of the oviraptorosaur
Coincidentally, the egg stealing dragon was nailed to the "column of shame" starting from one nest of eggs, and its "injustice" was also related to another nest of eggs.
In early 2021, Professor Bi Shundong of Yunnan University published a paper in the international journal Science Bulletin as the first author to justify the name of the platycopods.
"We have ample evidence that the 'innocent' of the oviraptorosaurs are really not 'thieves.'" Bi Shundong said.
Evidence 1: Egg hatching posture in birds. The paper describes a group of platycopod fossils found in Ganzhou, Jiangxi, China, about 70 million years ago, in the Late Cretaceous strata. Rarely, this group of fossils is preserved in an incubation position!
This adult oviraptorosaur is 2 meters long and its body is located in the center of the nest, completely covering the top of the nest. Its forelimbs appear backwards and downwards open, with the hind limbs folded under the body, in line with the hatching posture of modern birds.
"If you only look at the posture, you can't completely determine that the oviraptorosaur will incubate eggs, because as early as the 1990s, scientists have found similar incubating posture specimens in Inner Mongolia and Mongolia's Gobi region." We started with eggs and started our research. In Bi Shundong's view, in order to do a "not guilty defense" for the "thief", there must be full evidence, and the egg is an important breakthrough.
Evidence two: Asynchronous hatching of birds. Oviraptorosaurs are theropod dinosaurs that lived between 125 million and 66 million years ago. From 1923 to the present, expeditions and archaeological teams have found adult individuals lying on egg nests or at the edge of egg nests in Mongolia and the Gobi region of Inner Mongolia, but different scholars have different interpretations of these specimens. Some scholars believe that oviraptorosaurs may have been "protecting eggs" like crocodiles; others believe that the fossils found may have been oviraptors laying eggs rather than hatching eggs, as evidenced by the fact that the number of eggs preserved with adult individuals is not fixed, ranging from 6 to 22.
And this study fully allows the egg babies to "talk" and defend their parents.
In addition to the adult oviraptorosaur, this group of fossils in Ganzhou, Jiangxi Province, has 24 dark green eggs, slightly larger than ostrich eggs, which are arranged in three rings, and the shells of 7 eggs have been broken, revealing 7 embryos, and these embryos are at different stages of bone development.
"These eggs contain embryos, so that the 'egg laying theory' is self-defeating." Xu Xing, corresponding author of the paper and a researcher at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, said.
In addition, the researchers used geochemical methods, embryonic bone phosphate and oxygen isotope assays to find that the incubation temperature of the same layer of eggs was different. "This means that the 24 baby oviraptorosaurs will break their shells at different times." This also proves that oviraptorosaurs already have the characteristics of 'asynchronous hatching' that appears in some living birds, which is a more advanced incubation method in living birds. It can be said that the reproductive methods of dinosaurs are far more complex than previously recognized. ”
Evidence Three: The "stomach stones" of birds. Paleontologists also found several sleek stomach stones in the stomach of this adult oviraptorosaur. "This proves that Oviraptorosaurus may have used stones in the stomach to help digestion, indicating that they are vegetarians and eat plants, so how could they steal eggs to eat?" Bi Shundong asked rhetorically.
Will the father of the egg stealing dragon incubate the egg and crush the egg?
The fossils also convey an interesting message: the egg is probably hatched by a male oviraptorosaur.
The researchers did a histological analysis of the adult fossil, and from its structure, it was inferred that there was a 60% probability that it was male. "Generally speaking, after the female lays eggs, the calcium in the body will be seriously lost, and its tissue structure will be very different from that of the male, but this fossil is not the case." Bi Shundong said, "We started from the analysis of bone tissue, determination of growth lines, analysis of calcium content, etc., and came to the speculation that the egg-stealing dragon who hatched eggs was 'Daddy'. ”
Oviraptorosaurs vary widely in size, ranging from kilograms to tons. In the egg nest of the oviraptor, the arrangement of the eggs is very unique: the middle of the egg nest is piled with soil, and the eggs are leaning against the edge of the pile, arranged in a circle, up to 3 circles. As the dinosaur grew in size, the space in the middle grew larger and larger, like a donut.
From this set of fossils, the egg nest has 3 circles of eggs, and the body of the hatching egg oviraptor is located in the center of the egg nest. First, the oviraptorosaur can sit directly on it, and the body weight can be concentrated in the area without eggs in the middle. Second, the feathers around the body can cover the egg. In this way, not only will it not sit on the broken egg, but it can also provide heat to it.
"I have to say that the intelligence of dinosaurs is beyond our imagination, and while humans are still worried about whether the eggs will be crushed, they have already figured out a feasible way." Xu Xing said.
Can the name of the Oviraptorosaurus be changed?
Bi Shundong restored the process of the disaster that the egg-stealing dragon family suffered. One day 70 million years ago, near a ridge near a lake in Ganzhou, Jiangxi Province, a father of egg-stealing dragons was incubating eggs, and there were 24 babies under it waiting to break their shells. Unexpectedly, a mudslide suddenly occurred, and the dragon father who was concentrating on incubating the eggs did not have time to react, and was quickly buried by the pouring sediment, so the "father's love is like a mountain" egg incubation posture was frozen by nature.
If the charge of plagiarism is not convicted, can it be given a new name?
No way. Bi Shundong explained that the International Zoological Nomenclature Law stipulates that a named species must be named accurately with its earliest valid name, even if the name causes a great misunderstanding, it cannot be changed.
"I hope that parents and teachers must return the innocence of the oviraptorosaurus when telling the story of the oviraptor to the children, they are really kind parents who love their babies." Xu Xing said. (Reporter Yue Ranran)
Source: Xinhua Daily Telegraph