by Mary Caperton Morton Tuesday, June 5, 2018
Late Cretaceous skies might have been more crowded than previously thought. Until recently, scientists thought the dearth of pterosaur fossils found from the Late Cretaceous meant that the flying reptiles were in decline before the catastrophic end of the Mesozoic. But the recent discovery in Morocco of several new pterosaur species suggests this unique branch of reptiles may have been thriving just before the end-Cretaceous extinction.
The characteristics that made pterosaurs such fantastic fliers also explain why they are not well represented in the fossil record.
“To grow so large, and still be able to fly, pterosaurs evolved incredibly lightweight skeletons, with the bones reduced to thin-walled, hollow tubes like the frame of a carbon-fiber racing bike,” said Nick Longrich, a paleontologist at the University of Bath in England and lead author of the new study, published in PLOS Biology, in a statement. “Unfortunately, that means these bones are fragile, and so almost none survive as fossils.”
Working in a phosphate mine in northern Morocco that dates to the Maastrichtian Age — the latest part of the Cretaceous, between 72 million and 66 million years ago — Longrich and colleagues recovered a handful of bones from specimens of at least seven different species representing three pterosaur families, making the assemblage “the most diverse known Late Cretaceous pterosaur assemblage,” the team wrote. With wingspans ranging from 2 meters to more than 10 meters, the species “show a large range of variation in size and skeletal proportions, suggesting that they occupied a wide range of ecological niches,” they added.
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