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Death in the wild is often brutal and violent. But for the small bird-like dinosaur of the late Cretaceous period, its end was relatively peaceful, as it curled up for a nap and never woke up.
This is what scientists explain from the position of dinosaur fossil skeletons. With the creature’s head resting on its limbs and its tail snugly wrapped around its body, its relaxed posture resembled that of a relaxed body. Birds of today Being still, suggests that these dinosaurs not only looked like birds, but may even have acted like them.
Paleontologists have unearthed a nearly complete dinosaur skull and skeleton in the Gobi Desert in Mongolia’s Barun Guyot Formation, and most of the bones are still arranged in the animal’s original death position, researchers reported Wednesday in the journal. One added.
The animal’s long neck wraps around the right side of its body, and its head is tucked to the side, resting on its right knee. Its hind legs are tucked under, and most of its tail is curled over the left side of its body.
The study authors identified it as an alvarezsaurid, a small species Theropoda (bipedal carnivorous dinosaur) with a long tail and legs and short forelegs. Alvarezosaurids were part of a larger group of dinosaurs called maniraptorans, which included birds and the bird-like dinosaurs that were their closest relatives.
Alvarezsaur’s diminutive posture mimics two other dinosaur fossils discovered in Mongolia that were also curled up in a bird-like sleeping position: Sinornithoides yungii and Mei longi. These are two types of dinosaur, another type of dinosaur in the maniraptoran group, which was more closely related to birds than Alvarezsaurus.
Kota Kubo
Jaculinykus yaruui lived about 70 million years ago. (A) Photograph of a fossil skeleton found in the Gobi Desert in Mongolia. (B) Illustration showing skeletal elements, including a green skull and red pectoral girdle and forelimbs. (c) Reconstruction of the dinosaur, with gray areas indicating missing parts.
This new fossil suggests that this sleeping behavior may have been more common in non-avian relatives of the first birds, the researchers report.
“We’ve all seen ducks sleeping with their heads tucked under their wings. “Then you see this little dinosaur in the same sleeping position,” said paleontologist Dr. Jingmai O’Connor, curator of fossil reptiles at the Field Museum of Natural History in Chicago.
“This is clear evidence of unique behavior in birds today. “Now, we can say that this is not a unique trait in birds,” O’Connor, who was not involved in the study, told CNN.
Scientists who examined the fossil decided that it was a species new to science and gave it a fierce name: Jaculinykus yaruui. The genus name comes from jaculus, a mythical dragon, and onykus, which means claw in ancient Greek, while the species name comes from yaruu, a Mongolian word meaning haste or speed.
Mark A. Garlic
After the Chicxulub impact weeks or months ago, the remaining non-avian dinosaurs struggled to survive. The heat from falling debris initially raised temperatures so high that many animals died within days. A few weeks later, our planet’s atmosphere became clogged with soot, dust and other sediments, which isolated the sun, and global temperatures plummeted. Without the sunlight necessary for photosynthesis, plants around the world would die, causing the food chain to collapse. Here, a lone, injured, and starving Dakotaraptor surveys the remains of his territory in what, 66 million years later, is known as Hell Creek.
Scientists say that the asteroid that wiped out the dinosaurs stopped a process important for life on Earth
Jaculinykus yaruui lived about 70 million years ago at the end of the Stone Age Cretaceous Period It was only about 3 feet long (about 145 million to 66 million years ago) from nose to tail tip, said study lead author and paleontologist Kohta Kubo, a doctoral candidate at Hokkaido University’s Paleobiology Research Group. Japan.
“This specimen was considered a partial skeleton when it was discovered, but once prepared, it represents a nearly complete and detailed skeleton that maintains lifelike posture,” Kubo told CNN via email. “This is the first definitive record of this posture in alvarezosaurs as well as early branching maniraptoran dinosaurs.”
Jaculinykus yaruui’s closest relative is a small alvarezsaurid called Shuvuuia deserti, Kubo said. Typical characteristics include the shape of the nostrils, the relationship of the jaw muscles to the skull, and the shape of the limb bones.
“This is a beautiful specimen, and it’s always exciting to discover new diversity of dinosaurs, especially alvarezosaurids,” O’Connor said.
Alvarezsaurids are not the most well-known group of dinosaurs, but they have long fascinated scientists with their extremely short arms and hands, which in some species ended in a single large toe that grew spike-like claws.
“The type of fossil that is so well preserved that it records behavior is extremely rare,” O’Connor said. “It’s exciting that we have some additional evidence that definitely shows that this sleeping position is more widespread.”
In modern birds, this behavior helps them maintain body heat; According to research, this likely served a similar purpose to the maniraptor dinosaur, which also curled up before sleeping. During its evolution, Alvarezsaurus shrank in size. This “radical miniaturization” may have caused non-avian dinosaurs to adopt the same thermoregulatory strategies as their avian cousins, Kubo said.
Additionally, the tiny, sleepy Jaculinykus yaruui “highlights that this bird-like thermoregulatory behavior evolved before the advent of powered flight technology.” “Jaculinykus is an important example that alvarezsaurids had more similarities to living birds – not only in skeletal features but also in behavioral traits.”
Mindy Weisberger is a science writer and media producer whose work has appeared in Live Science, Scientific American, and How It Works.
2023-11-20 15:05:29
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