Imma Perfetto
Cosmos science journalist
Pterosaurs were the first vertebrates to evolve active flight, soaring through the skies until their untimely demise 66 million years ago. But new analysis of fossilised footprints shows that some of these winged reptiles were just as comfortable legging it on the ground.
Palaeobiologists analysed pterosaur tracks using 3-dimensional modelling, and compared their characteristics – such as digit length and soft tissue pad structure – to those of fossilised skeletons.
Their findings support the idea that pterosaurs underwent a major ecological shift about 160 million years ago, mid-way through the Mesozoic era, when several groups became more terrestrial.
Robert Smyth, a doctoral researcher at the University of Leicester in the UK and lead author of a Current Biology study describing the research, says footprints offer a unique opportunity to study pterosaurs in their natural environment.
“They reveal not only where these creatures lived and how they moved, but also offer clues about their behaviour and daily activities in ecosystems that have long since vanished,” says Smyth.
This is because unlike body fossils, which can be moved from their original location, tracks usually stay where they were made.
But even though fossilised pterosaur tracks are just as common as their skeletons, Smyth says they are often overlooked.
“By closely examining footprints, we can now discover things about their biology and ecology that we can’t learn anywhere else,” he adds.
Smyth and his colleagues have now shown that at least 3 different types of tracks match the feet of distinct clades of pterosaurs: ctenochasmatoids; dsungaripterids; and neoazhdarchians.
Footprints by neoazhdarchians – the clade which included Quetzalcoatlus, the largest flying animal ever, with a wingspan of 10m – have been found in coastal and inland areas around the world.
These footprints are narrow, with deep heel and faint digit impressions, and sometimes even prominent claw marks.
Some of these tracks are present until the asteroid impact 66 million years ago, which led to the extinction of pterosaurs and their dinosaur cousins.
Another group of pterosaurs, ctenochasmatoids, which are known for their long jaws and needle-like teeth, left behind tracks found mostly in coastal deposits.
Their footprints are large and triangular, with long metatarsals and short digits.
The abundance of these tracks suggests that these pterosaurs were far more common in coastal environments than their rare body fossils indicate.
The third type of footprint was discovered alongside fossilised skeletons of a clade of pterosaur known as dsungaripterids.
These animals were most likely specialist shellfish feeders, with toothless, curved jaw tips used to pry out prey, and large, rounded back teeth for crushing them.
Smyth says that tracks provide a wealth of information about how pterosaurs moved, behaved, and interacted with their environments.
“By closely examining footprints, we can now discover things about their biology and ecology that we can’t learn anywhere else,” he says.
