Paleontologists say they’ve discovered the fossilized remains of a small-bodied pterosaur, a prehistoric flying reptile, which lived roughly 77 million years ago (Late Cretaceous epoch) and had a wingspan of 5 feet (1.5 m).
Artist impression of the small-bodied azhdarchoid pterosaur from British Columbia, Canada. Image credit: Mark Witton.
The new pterosaur belonged to a group of short-winged and toothless pterosaurs called the azhdarchids.
It is unusual as most Late Cretaceous pterosaurs were much larger with wingspans of 13-36 feet (4-11 m).
Previous studies suggest that the Late Cretaceous skies were only occupied by birds and large pterosaurs, but this new finding, which is reported in the journal Open Science, provides important information about the diversity and success of Late Cretaceous pterosaurs.
“This new pterosaur is exciting because it suggests that small pterosaurs were present all the way until the end of the Cretaceous, and weren’t outcompeted by birds,” said lead author Elizabeth Martin-Silverstone, from the University of Southampton.
“The hollow bones of pterosaurs are notoriously poorly preserved, and larger animals seem to be preferentially preserved in similarly aged Late Cretaceous ecosystems of North America.”
“This suggests that a small pterosaur would very rarely be preserved, but not necessarily that they didn’t exist.”
Although fragmentary and poorly preserved, the specimen is the first associated remains of a small-bodied pterosaur from the Late Cretaceous.
The fossilized bones (a humerus, dorsal vertebrae and other fragments) were found on Hornby Island in British Columbia in 2009.
A restoration of a small-bodied pterosaur, representing the atypically diminutive Late Cretaceous azhdarchoid specimen, against a modern housecat (around 30 cm tall at shoulder). Image credit: Mark Witton.
“The specimen is far from the prettiest or most complete pterosaur fossil you’ll ever see, but it’s still an exciting and significant find,” said co-author Dr. Mark Witton, from the University of Portsmouth.
“It’s rare to find pterosaur fossils at all because their skeletons were lightweight and easily damaged once they died, and the small ones are the rarest of all. But luck was on our side and several bones of this animal survived the preservation process.”
“Happily, enough of the specimen was recovered to determine the approximate age of the pterosaur at the time of its death. By examining its internal bone structure and the fusion of its vertebrae we could see that, despite its small size, the animal was almost fully grown.”
“The specimen thus seems to be a genuinely small species, and not just a baby or juvenile of a larger pterosaur type.”
“The absence of small juveniles of large species – which must have existed – in the fossil record is evidence of a preservational bias against small pterosaurs in the Late Cretaceous,” Martin-Silverstone said.
“It adds to a growing set of evidence that the Late Cretaceous period was not dominated by large or giant species, and that smaller pterosaurs may have been well represented in this time.”
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Martin-Silverstone E. et al. 2016. A small azhdarchoid pterosaur from the latest Cretaceous, the age of flying giants. R. Soc. Open Sci. 3: 160333; doi: 10.1098/rsos.160333
