Fossilized footprints unearthed in Korea have shown that pterosaurs, which flew through the skies 100 million years ago, also pursued prey on land. It had been assumed from their skeletal structure that pterosaurs could walk on the ground and chase prey without difficulty, but this is the first time footprints directly showing this have been discovered.
An international research team led by Professor Kim Kyeong-soo of Jinju National University of Education said in the international journal Scientific Reports on the 16th that analysis of footprints from 106.5 million years ago found in the Jinju Formation in Jinju, South Gyeongsang Province, confirmed that a large pterosaur was chasing a small animal.
◇Footprints of a pterosaur quickly following a small animal
Pterosaurs were large reptiles that flew through the air. They are thought to have appeared 228 million years ago, dominated the Mesozoic era along with land-dwelling dinosaurs, and gone extinct together 66 million years ago. The team gave the newly found footprints the scientific name Jinjuichnus procerus, meaning "pterosaur footprints with elongated forefeet discovered in Jinju."
Academics focused on this discovery because, right next to the pterosaur's footprints, there were side-by-side tracks of a small terrestrial animal presumed to be a salamander or a lizard. Judging from the footprints, the small animal was walking in a steady direction and then suddenly turned 25 degrees. At the same time, its stride length greatly increased. It can be seen as the animal being startled by something and urgently speeding up to flee.
The researchers explained that the creature that startled the small animal was a pterosaur. That is because the pterosaur's footprints continued in the direction the small animal fled. Analysis indicated the pterosaur walked quickly at 0.8 meters per second while chasing the small animal.
Of course, it is also possible the two animals happened to pass the same spot at different times and left their traces. However, the team said it is reasonable to conclude that the pterosaur pursued the small animal with only a very short time gap, given the similar depth and preservation of the footprints.
◇First footprint evidence proving terrestrial hunting
The maker of the pterosaur footprints was inferred to be a pterosaur of the neoazhdarchia lineage that lived in the Cretaceous period of the Mesozoic era (from 146 million to 66 million years ago). In paleontology, a steady hypothesis has held that neoazhdarchian pterosaurs were "terrestrial predators" that walked on the ground like today's storks or cranes and preyed on small animals.
Professor Kim Kyeong-soo said, "Looking at skeletal fossils from overseas, neoazhdarchians were interpreted as having large bodies, long necks, and sturdy legs, which would have favored walking on land and catching prey." However, the terrestrial predator hypothesis was based only on skeletal form, and no fossil evidence directly showing terrestrial hunting behavior had been found anywhere.
The researchers said, "The fossils from the Jinju Formation could be the first footprint evidence that pterosaurs hunted vertebrates on land." In other words, the newly found footprints captured the moment when a predatory pterosaur was chasing a small animal as prey.
The paper lists Dr. Jeong Jong-yun, a postdoctoral researcher at the University of Texas at Austin, as co-corresponding author, and Dr. Choi Byung-do of the Daegu National Science Museum and Professor Lida Xing as co-authors. The pterosaur and small animal footprint specimens analyzed in this study are on display at the Jinju Pterosaur Footprint Exhibition Hall.
◇Recently revealed with a furry look as well
Scientists have recently unveiled successive new views of pterosaurs. Not only their behavior but also their appearance has turned out to differ from what was previously thought. It has been revealed in succession that pterosaurs had hair-like filaments similar to bird feathers even if they lacked wings. Pterosaurs are thought to have flown like gliders by stretching thin membranes of skin between their limbs, like today's flying squirrels or bats. They flew in the sky, but the ancestors of birds were dinosaurs that gave rise to Archaeopteryx.
A team at the University of Bristol in the United Kingdom reported in the international journal Nature Ecology & Evolution in 2019 that they found four types of filaments in a pterosaur that lived 160 million years ago in China during the Jurassic period. In 2021, Chinese scientists also reported finding traces of feathers in a Jurassic small pterosaur fossil excavated in Hebei Province.
Scientists believe pterosaur filaments were not used directly for flight but helped maintain body temperature and reduce drag. They also likely sufficed for displaying themselves to potential mates. In fact, scientists have found pigment structures in pterosaur filaments. These closely resembled those found in bird feathers or mammalian hair.
Dinosaurs evolved into birds through Archaeopteryx 150 million years ago. It was recently revealed that dinosaurs such as Tyrannosaurus also had body-wide filaments used for insulation and mating display. Based on this, scientists inferred that feathers evolved earlier than Archaeopteryx, from the common ancestor of pterosaurs and dinosaurs.
References
Scientific Reports (2026), DOI: https://doi.org/10.1038/s41598-026-48019-y
PeerJ (2021), DOI: https://doi.org/10.7717/peerj.11161
Nature Ecology & Evolution (2019), DOI: https://doi.org/10.1038/s41559-018-0728-7