Pterosaurs, the first true flying vertebrates, were crucial in Mesozoic terrestrial ecosystems. However, our understanding of their ability to move around on the ground and, more broadly, their terrestrial paleoecology needs to be improved.
Paleontologists at the University of Leicester‘s Centre for Palaeobiology and Biosphere Evolution have identified key evolutionary adaptations that enabled ancient pterosaurs to achieve enormous sizes. Their study revealed that efficient ground locomotion significantly influenced the maximum length of these flying animals, with some boasting wingspans of up to 10 meters.
The research involved a comprehensive examination of the hands and feet of pterosaurs from various regions and periods in their evolutionary history.
The researchers found significant variation in the hands and feet of pterosaurs, akin to the diversity observed in modern birds. This suggests that pterosaurs were not solely aerial creatures but were adapted to various terrestrial lifestyles, ranging from tree-climbing in earlier species to more ground-dwelling behaviors in later ones.
As the first true flying vertebrates, pterosaurs exhibit remarkable adaptations. This study highlights their diverse living habits during the Mesozoic era (252-66 million years ago), revealing a complex interplay between their aerial and terrestrial lifestyles.
Early pterosaurs were highly specialized for climbing, featuring hand and foot modifications akin to those seen in climbing lizards and woodpeckers. Their adaptations allowed them to cling to vertical surfaces, but this lifestyle was physically demanding, limiting them to arboreal habitats and smaller body sizes.
A significant evolutionary shift occurred during the Middle Jurassic period when their hands and feet evolved to resemble those of ground-dwelling animals. This transition to ground-based movement expanded their ecological opportunities, enabling diverse feeding strategies and freeing them from size constraints. As a result, some pterosaurs evolved to massive sizes, with wingspans reaching up to 10 meters.
Co-author Dr David Unwin from the University of Leicester added: “In early pterosaurs, the hind limbs were connected by a flight membrane which severely impeded walking and running. In later, more advanced pterosaurs, this membrane separated along the midline, allowing each hind limb to move independently. This was a key innovation that, combined with changes to their hands and feet, greatly improved pterosaurs’ mobility on the ground.”
“Freed from the constraints of climbing, these later pterosaurs could grow to enormous sizes, with some species becoming true giants of the Mesozoic.”
The structure of pterosaur hands and feet provides crucial insights into their evolutionary adaptations. Early pterosaurs had relatively short bones at the base of their fingers and toes, with elongated bones further out. These bones ended in large, curved claws that allowed for a strong grip ideal for climbing.
In contrast, more advanced pterosaurs later displayed a different configuration: longer base bones and shorter, flatter claws, indicating adaptations for walking rather than climbing. These findings highlight the importance of studying all aspects of pterosaur locomotion, not just their ability to fly.
We can better understand their roles within ancient ecosystems by investigating their terrestrial and arboreal lifestyles.
When pterosaurs ventured onto land, they encountered various animals, including dinosaurs and other reptiles. To minimize competition, pterosaurs adapted to exploit ecological niches that combined flying and walking abilities.
This led to developing unique feeding strategies, such as the evolution of hundreds of fine, needle-like teeth for filter-feeding. Remarkably, this adaptation appeared at least 120 million years before the first flamingos evolved, showcasing the innovative ways pterosaurs occupied their environments.
Journal Reference:
- Robert S.H. Smyth, Brent H. Breithaupt, Richard J. Butler, Peter L. Falkingham, David M. Unwin. Hand and foot morphology maps invasion of terrestrial environments by pterosaurs in the mid-Mesozoic. Current Biology, 2024; DOI: 10.1016/j.cub.2024.09.014
