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A strange fossil has helped scientists discover an unusual bird that lived among the dinosaurs 120 million years ago, and the discovery is changing the way researchers think about avian evolution.
The previously unknown species was named Imparavis attenboroughi, meaning “Attenborough‘s strange bird’ in Latin in honor of the British naturalist Sir David Attenborough.
All birds are descended from dinosaurs, and some of the earliest were similar to them. But Imparavis, which belonged to a different group of birds called enantiornithines, probably looked more like the birds we know today, according to a new study published Tuesday in the journal Cretaceous Research.
Enantiornithines are called “opposite birds” because they had a shoulder feature that was very different from that of modern birds.
“Enantiornithines are very strange. Most of them had teeth and still had clawed digits,” lead study author Alex Clark, a doctoral student at the University of Chicago and the Field Museum of Natural History, said in a statement. “If you were to go back 120 million years in northeast China and walk around, you might see something that looked like a robin or a cardinal, but then it would open its mouth, and it would be stuffed with teeth, and he would raise his wing, and you would understand that he had little fingers.”
But Imparavis was the first bird of its kind to be toothless in a landscape full of birds with teeth, according to the study.
“Prior to Imparavis, this group of birds was known to be toothless about 70 million years ago,” Clark said. “With Imparavis, it happened almost 48 million years earlier. Today, all birds lack teeth. But back in the Mesozoic, a small toothy mouth was the norm. If you saw one without teeth, it would be odd – and that’s what Imparavis was.”
Looking for a strange fossil
The fossil was first discovered by an amateur collector near the village of Toudaoyingzi in northeastern China and donated to the Shandong Pingyi Tianyu Natural Museum. When Jingmai O’Connor, the Field Museum’s associate curator of fossil reptiles, visited the Shandong museum’s collections a few years ago, the fossil caught her attention.
“I think what drew me to the specimen was its lack of teeth — it was its tail,” study coauthor O’Connor, who is also Clark’s adviser, said in a statement. “It had a huge decipital crest – a bony process jutting out at the top of the upper arm bone, where the muscles attach. I’ve seen crests like that in Late Cretaceous birds, but not in Early Cretaceous ones like this one. That’s when I first suspected it might be a new species.”
Clark, O’Connor and their colleagues began studying the fossil in early 2023, and were surprised by the bird’s lack of teeth in addition to its one question forelimbs, or wing bones.
Imparavis had large attachment points for the muscles in its wing bones, suggesting that it could generate a lot of power with its wings and that it had a strong downward wing beat, which would be like pushing a huge amount of air pressure up, Clark said.
“We could be looking at very strong wing beats. Some features of the bones are similar to those of modern birds such as puffins or murres, which can become crazy quickly, or quail and pheasants, which are small, strong birds but produce enough power to sail almost vertically at a moment’s notice when threatened,” Clark said.
Although modern birds have fused forelimb digits, enantiornithines still had independent movement in the “little fingers” on their wings.
“Most of the ‘hand’ would have been covered in tissue to help form the wing, but the small claws (and they were very small claws) may have been used for food, climbing aid or other which was not thought to be handled. — behavior,” Clark said.
The secrets of avian evolution
Neither Clark nor his colleagues can say for sure what kind of food Imparavis ate or exactly why it was toothless. Features of the bird’s hind limbs suggest that it probably hunted on the forest floor, perhaps in search of fruit, seeds or insects.
The bird, like other enantiornithines, did not have a digestive organ called a gizzard that helps modern birds push up their food for easier digestion, “so the evolutionary pressures that Toothlessness in other groups of dinosaurs similarly led to enantiornithines like Imparavis,” Clark said.
As other birds lost their teeth over time, they ingested stomach stones to create a gastric mill to help crush the food they ate. But Imparavis did not behave that way. Until scientists find more samples of Imparavis, what the bird ate and how it digested food remains a mystery.
Imparavis would likely be seen hopping and walking on the ground like modern robots, Clark said.
“Most enantiornithines seem to have been quite arboreal, but the differences in the structure of the forelimb of Imparavis suggest that, although it probably still lived in the trees, it may have descended to the ground to feed, and that could mean he had a unique diet. compared to other enantiornithines, which could also explain why it lost its teeth,” said O’Connor.
One of the main questions researchers remain about bird evolution is why the more diverse enantiornithines went extinct 66 million years ago with the dinosaurs, while another group called ornithuromorphs survived and gave rise to new birds. fashion to emerge.
“Some thought it might be because ornithuromorphs were more commonly associated with water/river systems, others thought perhaps a different metabolism, and still others perhaps differences in nesting or raising young,” a Clark said in the statement. “This is where more fossil specimens and more statistical models will come into play in the future – so stay tuned!”
Understanding extinct species
Clark is currently researching new specimens that show the surprising similarities and differences between ancient and modern birds, showing what “paradoxical little creatures” they can be.
Clark credits his interest in the natural sciences to watching Attenborough’s nature documentaries, hence the name of the new fossil.
“It’s a great honor to have your name attached to a fossil, especially one as amazing and important as this. “The history of birds seems to be more complicated than we knew,” Attenborough said in a statement.
But studying extinct animals doesn’t just shed light on the past—it raises awareness for the future, according to the researchers.
“Learning about enantiornithines like Imparavis attenboroughi helps us understand why they went extinct and why modern birds survived, which is really important to understanding the sixth mass extinction we’re in,” said O’ Connor. “The greatest crisis facing humanity is the sixth mass extinction, and paleontology provides the only evidence we have of how organisms respond to environmental changes and how animals respond to stress on other dying organisms.”
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