The first known dinosaur belly button was found in a fossil

Forget the dinosaurs were involved in a fierce fight. Put aside the terrifying fangs and claws. Scientists have discovered a softer side to dinosaurs: the reptile’s equivalent of a belly button.

For the first time ever, scientists have identified a secret scar on a non-avian dinosaur. The paper The announcement of this discovery was published in BMC Biology, and it is another exciting discovery from a rare and well-preserved discovery Psittacosaurus Fossil from China. (Other delights of the same sample include A cloaca And the Shading camouflage.)

For mammals, belly buttons are the result of the umbilical cord detaching at birth. But reptiles and birds, whose method of reproduction consists in laying eggs, do not have such a cord. Inside the egg, the abdomen of the fetus is connected to the yolk sac and other membranes. The scar occurs when the embryo separates from these membranes just before or when it hatches from the egg. Known as the umbilical scar, it is the non-mammary form of the belly button. And this is exactly what the international team of scientists claims to have found in this fossil.

Psittacosaurusa bipedal dinosaur that lived during the beginning of the Cretaceous period, is an early form of ceratopsian, a type of beaked herbivore which, later in the same geological period, includes Triceratops. Perhaps the most dazzling of the species ever found is still frozen over time, lying on its back, complete with skin bristles and a tail. Their preservation, at approximately 130 million years old, is astounding. And although it appeared to the public in 2002, it continues to open up new and unique horizons.

Michael Bateman studied this fossil in detail. He’s a paleontologist, assistant professor at the Chinese University of Hong Kong, and co-author of the new research. He and co-author Thomas J. Kay, of the Foundation for the Advancement of Science, were able to visit the fossil in Germany in 2016 at the Senckenberg Research Institute and Museum of Natural History in Frankfurt. Invented the two worlds laser stimulated fluorescence (LSF), a relatively new imaging technology. In this non-destructive way, they were able to detect details In fossils that might otherwise remain invisible.

This “micro-scar,” as Pittman described it in an email, was found using LSF. Thanks to LSF, the team was able to study the parameters of the skin — its patterns, wrinkles, any scars — in great relief. For help with work on the skin, the team turned to Phil Bell, a dinosaur paleontologist at the University of New England’s Research Center for Paleontology in Australia, who has extensive experience with the subject. Bill is the lead author of the new paper.

“LSF brings out the details in an amazing way,” Bell said in a video interview. “It really looks as if the animal could just get up and walk away. You can see all the wrinkles and the little bumps in the skin. They look so fresh. Imagining these animals as living, breathing creatures, not just dead skeletons, is what fascinates me. Reviving them is one of the main goals for my work.”

The team found evidence of wrinkles in the skin, but not in the abdomen where the umbilical scar is. Injuries that have healed show regenerated tissues; There will be a clear break in the volume patterns, with a fine granulation tissue over the affected area.

Instead, Bateman explained, “[t]Secret scales have regular sizes, smooth margins, and are arranged along the midline Psittacosaurus. This indicates that the scar was not the result of an injury.”

In order to determine the age of dinosaurs, most of them chop up bones. The extreme rarity of this fossil means that researchers want to avoid any such devastating analysis. So the team compared the length of the femur with that of the others Psittacosaurus The samples were estimated that this particular animal was about 6 or 7 years old. In other words, this dinosaur was approaching sexual maturity.

Not all reptiles or birds living today retain a secret scar during adulthood. The authors note that the American alligator is one particular exception (Mississippi alligator). In addition, some scarring are caused by yolk sac infection in birds or crocodiles raised in poor conditions. With all these variables, it’s not a given that all dinosaurs – or even all Psittacosaurus– It will have a scar in the navel.

Bateman described how he and Kai collected a huge library of LSF data from Psittacosaurus Sample in 2016, “which they are still combing and studying.” This led to paper That year a reverse shading camouflage pattern was observed, the first to be identified in a dinosaur. We planned to analyze the LSF data further because our images provided a lot of additional information about the skin.”

We are currently finalizing a detailed description of the skin Psittacosaurus,” he added. “This requires us to look at every square inch of the fossil.” And this is how the discovery of the secret scar happened.

Looking at preserved leather in such detail is Bell’s area of ​​expertise. Few scientists focus on fossil skin, he explained, making any research vulnerable to exciting discoveries. Moreover, he said, when speaking with the general public, he found that they were often surprised to hear that fossil skin existed at all, let alone what it reveals. Even in paleontology, he says, the predominant focus is still bones.

““I think the important thing is that the scaly reptiles are interesting,” Bell said. He hopes that both the public and the broader scientific community will realize just how much we have yet to learn about dinosaur skin and its biological function. Noting that “the skin is the largest organ in the body,” he noted how scales protect, for example, modern reptiles from drying out and UV rays. Bill wants to change the perception that scales are less exciting than feathers.

“It’s a pretty amazing specimen,” Bell said. Psittacosaurus fossil. And the fact that it still surprises for 20 years [from the time] It was first announced to the public which is exceptional, due to the development of these new imaging technologies. “

These surprises – the knowledge we have gained so far – would not have been possible had the fossil remained in private hands. that’s cool Psittacosaurus a sample he have controversial history. Its exact provenance is unknown, as it passed from one private collector to another before being purchased by Senckenberg. Then, as now, there are those who hope that the fossil to China. At the end of their paper, the authors wrote: “There is an ongoing debate regarding the legal ownership of this specimen and efforts to return it to China have not been successful. Our international team made up of Australian, Belgian, British, Chinese and American members all hope to find and support a friendly solution to this ongoing debate. We think it is important to note that the specimen had been acquired by the Senckenberg Museum to prevent its sale in private hands and to ensure that it was available for scientific study.”

Jane Timmons (Tweet embed) is a freelance writer based in New Hampshire, who blogs about paleontology and archeology in mostmammoths.wordpress.com.