(CN) - Brain size indicates a few non-avian dinosaurs already suspected of having flight capability would have had the necessary neurological hardwiring, scientists say.
Research provides evidence that dinosaurs evolved the brainpower necessary for flight well before they actually took to the air as birds, the National Science Foundation noted Tuesday, when posting images to its gallery for the 2013 study.
Based on high-resolution X-ray computed tomographic (CT) scans, the study, published in Nature , July 31, 2013 takes a comprehensive look at the so-called "bird brain." Contrary to the cliché, the term describes a relatively enlarged brain that has the capacity required for flight and was present in one of the earliest known birds, Archaeopteryx, the American Museum of Natural History wrote in its press release for the study.
"Archaeopteryx has always been set up as a uniquely transitional species between feathered dinosaurs and modern birds, a halfway point," said lead author Amy Balanoff, a research associate at the American Museum of Natural History and a postdoctoral researcher at Stony Brook University. "But by studying the cranial volume of closely related dinosaurs, we learned that Archaeopteryx might not have been so special."
Birds have enlarged brains compared to other living reptiles. The extra capacity, most obvious in the forebrain, is important for providing the superior vision and coordination required to fly, the museum wrote.
For the study, the researchers used CT scanners at the University of Texas, Ohio University, Stony
Brook University, and the Museum to look inside the skulls of more than two dozen specimens, including modern birds, Archaeopteryx, and closely related non-avian dinosaurs like tyrannosaurs. By stitching together the CT scans, the scientists created 3-D reconstructions of the skulls' interiors. In addition to calculating the total volume of each digital brain cast, the research team also determined the size of each brain's major anatomical regions, the museum's press release stated.
"The story of brain size is more than its relationship to body size," said coauthor Gabriel Bever, an assistant professor of anatomy at the New York Institute of Technology.
"If we also consider how the different regions of the brain changed relative to each other, we can gain insight into what factors drove brain evolution as well as what developmental mechanisms facilitated those changes."
The researchers found that in terms of brain measurements, Archaeopteryx is not the only creature between non-avian dinosaurs and modern birds. "If Archaeopteryx had a flight-ready brain, which is almost certainly the case given its morphology, then so did at least some other non-avian dinosaurs," Balanoff said.
The researchers also examined another factor that is important to flight in modern birds: a neurological structure called the wulst, which is used in information processing and motor control. The team identified an indentation in the digital brain cast of Archaeopteryx that might be similar in position, structure, and evolutionary origin to the wulst seen in living birds.
This indentation is not found in non-avian dinosaurs that have bigger brains than Archaeopteryx, including bird-like oviraptorosaurs and troodontids presenting the research team with a new question to explore in the future, the museum reported.
Funding for this work was provided by the National Science Foundation and a Columbia University International Travel Fellowship. Timothy Rowe, from The University of Texas at Austin, also contributed to the study.
Emails requesting comment from Dr. Balanoff and the museum sent after hours Thursday received no response.
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