Transparent 3D model of a petrified bird’s skull and brain (pink). Credit: Christopher Torres/University of Texas at Austin
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Today, being “cocky” means forgetting where you left your keys or wallet. But 66 million years ago, it might have meant the difference between life and death — and might help explain why birds are the only dinosaurs left on Earth.
Research on newly discovered bird fossils led by the University of Texas at Austin has found that the unique shape of the brain may be the reason why a living bird ancestor survived the mass extinction that killed all other known dinosaurs.
“Living birds have brains that are more complex than any other known animal except mammals,” said lead researcher Christopher Torres, who conducted the research while receiving his Ph.D. He received his Ph.D. from the College of Natural Sciences at the University of Texas, and is now a Postdoctoral Fellow at the Ohio University National Science Foundation and Research Associate at UT Jackson’s School of Geosciences. “This new fossil allows us to test the idea that these brains played a key role in their survival.”
The fossil is about 70 million years old and has a nearly complete skull, a rare event in the fossil record that allows scientists to compare ancient birds with birds living today.
The results will be published on July 30, 2021 in the journal scientific progress.
Fossil skull of Ichthyornis, a bird that lived 70 million years ago during the late Cretaceous period. Credit: Christopher Torres/University of Texas at Austin
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The fossil is a new specimen of a bird named Actor, which became extinct at the same time as other non-marine dinosaurs and lived in what is now Kansas by the end of the year
The skulls of birds were tightly wrapped around their brains. Using computed tomography data, the researchers used skull Actor Like a template for making a 3D replica of his brain called an endocast. They compared these indoor broadcasts to broadcasts made to live birds and distant relatives of dinosaurs.
The ancestors of living birds had very different brain shapes from other dinosaurs (including other ancient birds). This suggests that brain differences may have influenced survival during the mass extinction that wiped out all non-floating dinosaurs. Credit: Christopher Torres/University of Texas at Austin.
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Researchers found that the brain Actor It has more in common with non-floating dinosaurs than with living birds. In particular, the hemispheres – where higher cognitive functions such as speech, thinking and emotion occur in humans – are much larger in living birds than in living birds. Actor. This pattern suggests that these functions may be linked to the continuity of mass extinctions.
“If a brain trait affects survival, we’d expect it to be in survivors but not in injuries, like Actorsaid Torres. “That’s what we see here.”
The search for skulls from ancient birds and closely related dinosaurs has been a challenge for paleontologists for centuries. Bird skeletons are notoriously fragile and rarely survive in the fossil record intact in three dimensions. Well-preserved skulls are extremely rare – but that’s exactly what scientists need to understand what their brains looked like in life.
“Actor “This is the key to solving this puzzle,” said Julia Clark, a professor at UT Jackson’s School of Geosciences and a co-author of the study. “This fossil helps bring us closer to answering some pressing questions about living birds and their survival among dinosaurs.”
Reference: “The Evolution of Bird Nerve Mass and Body Mass Through the Late Cretaceous Mass Extinction: The Shape of the Bird Brain Behind Other Dinosaurs” by Christopher R. Torres, Mark A. Norell, and Julia A. Clark, July 30, 2021 Available here. scientific progress.
DOI: 10.1126 / sciadv.abg7099
Mark Norell, curator and chair of the Department of Paleontology at the American Museum of Natural History, co-authored the study. This work was funded by the Science Education Program of the Howard Hughes Medical Institute, the Jackson School of Earth Sciences and the American Museum of Natural History.
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