for National Geographic News
The 4.7-foot (1.42-meter) skull of a giant flying reptile that lived among dinosaurs suggests that it might have hunted for food like modern birds known as skimmers, using its scissors-like bill to snatch prey as it glided over water.
Thalassodromeus sethi, a previously undescribed pterosaur which lived in the Araripe Basin of northeastern Brazil 110 million years ago, had a wingspan of as much as 15 feet (4.5 meters), according to scientists Alexander W. A. Kellner and Diogenes de Almedia Campos at Museu Nacional/Universidade Federal do Rio de Janeiro and at Museu de Ciências da Terra in Rio de Janeiro.
The pterosaur also had a large but thin bony crest. With the exception of one other species, T. sethi "has the proportionally largest crest known in any vertebrate, fossil or recent," the researchers report in the July 19 issue of Science.
Although scientists have been studying pterosaurs for over 200 years, a comprehensive understanding of their diversity and biology has been elusive due to the fragile nature of pterosaur fossils. Brazil's Araripe Basin is one of the few deposits where pterosaurs are found in large numbers with good preservation.
The fossil described in Science is rare in that the skull, from the early Cretaceous period, is almost completely intact. This allowed the researchers to perform a thorough analysis, gaining a better insight into T. sethi's feeding behavior, and into the function of cranial crests in pterosaurs.
The researchers speculate that T. sethi's crest may have served several purposes.
Grooves in the crest's bone show that it was densely packed with blood vessels, evidence that its primary function was probably to regulate its blood temperature, the scientists said. T. sethi might have been able to cool itself by circulating blood through the crest, dissipating excess body heat through convection.
It may also be that the crests' distinctive shapes and color patterns enabled the pterosaur to recognize kin or differentiate between the sexes.
Finally, the large size of the crest may indicate that it played a part in aerodynamics.
Carefully modulated flight would have been critical to T. sethi's survival. By comparing it to modern birds of the genus Rynchops (commonly called skimmers), Kellner and Campos concluded that T. sethi also fed by skimming across bodies of water and dipping its blade-like lower jaw into the water to scoop up its prey.
Its distinctive elongated skull and specialized jaws are almost certain evidence that T. sethi caught its prey using this method, the researchers said.
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