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A museum can amaze you with all its fossil specimens on display, but it's often only a small part of what's really there: the specimens in the back can be in drawers or be covered with plaster in boxes, quietly holding yet to reveal. secrets or other mysteries of the past. This is the case of an incredible bird fossil, discovered 25 years ago in Utah, but which has just been described.
The fossil is pretty nuts – an extinct bird the size of a turkey called an enantiornithine, apparently very capable of flying, and perhaps one of the most complete of its kind ever seen in North America . This explains why some dinosaurs have disappeared but others (the birds we see today) have been stuck.
"The skeleton tells an interesting evolutionary story. Just before their extinction, the enantiornithine birds had developed separately adaptations for advanced flight, just like modern birds, "said author Gizmodo, Jessie Atterholt, assistant professor at Western University of Health Sciences.
This fossil has a history that is a quarter of a century old. Paleontologist Howard Hutchison discovered it during a trip to the Grand Staircase-Escalante National Monument, in Utah, in rocks 75 million years old. Atterholt explained that a large number of paleontologists were aware of the "important" specimen, but never completed their analysis. Atterholt is particularly interested in the evolution of these enantiornithines and asked if she could work there. "We are finally getting there," she said. She, Hutchison and researcher Jingmai O'Connor published the results today in PeerJ.
The fossil skeleton, now a new named species Mirarce eatoni, consists of several vertebrae, the base of the spine that would support the feathers of the tail, almost all the bones of the left foot and some of the right, a humerus, a femur, the lowest bone of the leg found in birds called tarsometatarse, a triangle and other pieces. It was a bird and probably the size of a turkey. The most exciting is perhaps the ulna, or anterior bone, which had small coarse notches interpreted as "feathers". These are the characteristics present in today's birds that strengthen the feathers and indicate an advanced flight, said Atterholt.
"There is no doubt that it is one of the most important bird fossils of the dinosaur era," said Gizmodo Steve Brusatte, a paleontologist of the 39, University of Edinburgh not involved in the study.
This fossil tells the story of a group of birds that evolved parallel to the ancestors of modern birds, but did not survive the mass extinction. Its high level of preserved detail also demonstrates that a ton of diversity has failed to surpass the asteroid attack. But this deepens the mystery. After the meteor, only a few birds have survived and diversified among the 10,000 species of today. Brusatte explained the mystery:
"They might have had a beak and could eat seeds – a nutritious food source that can survive in the soil for decades or centuries, a food bank for the world that went to hell when the asteroid is falls. Or maybe these birds nestled on the ground, so they were not exterminated when the forests collapsed when the forests collapsed after the asteroid passed. Or maybe they could fly longer, or grow faster, or hide more easily. We do not really know. But this new discovery tells us that the birds that lived with the last dinosaurs were even more diverse than we thought, so it's a mystery why so few of them survived the asteroid.
Atterholt continues his research on these bones to study what was the bird and its evolution. She also discussed the recent controversy on the site of the fossil origin, Grand Staircase-Escalante. Recently, President Trump has reduced the size of this national monument. She pointed out that such decisions could end discoveries like this.
"This equipment could be destroyed and threatened with reduction in the size of the protected land."
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