The anatomy of some of the biggest and most ferocious dinosaurs of all time was the secret to their success. Like many modern birds, Tyrannosaurus, Apatosaurus And other giants had a complex network of air sacs that grew from their throats and lungs into their bones. The bags may also have made the dinosaurs breathe more efficiently and even help cool them down. But researchers were uncertain when and how this valuable adaptation first appeared in the animal kingdom.
Paleontologists are familiar with flying reptiles called pterosaurs, Allosaurusand including long-necked dinosaurs DiplodocusThe presence of sacs can be detected in depressions and cavities in fossilized bones, even when the soft tissue is long gone.new research in scientific report Rather than evolving air sac systems more than 235 million years ago, the last common ancestor of dinosaurs and pterosaurs, it suggests that different lineages developed these systems independently.
“Animals with air sacs have a huge advantage over us mammals,” says Tito Aureliano, a paleontologist at the University of Campinas in Brazil, who is the lead author of the new study. Many of the unique features of dinosaurs are made possible by these systems, he notes.
To investigate the origin of the sac, researchers turned to the bones of three ancestral dinosaur species. A CT scan was used to examine the outside of the bone, looking for openings or pockets that could accommodate air sacs. It was then compared to the bones of other animals such as modern crocodiles and deer, which are known to lack these structures.
The researchers were surprised to find that early dinosaur bones resembled the bones of crocodiles and deer more than those of the dinosaur’s later descendants. “It’s hard to believe that such air sacs evolved independently three times in separate dinosaur lineages,” but the new results suggest that scenario.
Ohio University paleontologist Patrick O’Connor, who was not involved in the study, confirms that early dinosaurs did not have these extensive air sac systems. He adds that this does not mean that reptiles were larger and more diverse, he adds, noting that some modern birds, such as ducks, have more minimal arrangements. , most likely indicating that the air sacs independently penetrated the bone multiple times.
“New fossils show more and more cases of convergent evolution,” said Aureliano, noting that this repeated development of important traits was part of what made dinosaurs so successful. suggests that
