Uncovering the Secrets of Ancient Pterosaurs: How Ground Movement Led to Gigantic Sizes

The evolutionary adaptations that allowed ancient pterosaurs to grow to enormous sizes have been pinpointed for the first time by palaeontologists in the Centre for Palaeobiology and Biosphere Evolution at the University of Leicester.

The discovery revealed a surprising twist — the ability to walk efficiently on the ground played a crucial role in determining how large the biggest flying animals could grow, with some reaching wingspans of up to 10 meters.

In a new study published in Current Biology, a team of researchers led by the University of Leicester examined the hands and feet of pterosaurs from around the world and across their entire evolutionary history. They uncovered a surprising level of variation similar to that seen across living birds. This discovery indicates that pterosaurs were not confined to a life in the skies but were also adapted to a wide range of terrestrial lifestyles, from tree-climbing in early species to more ground-based lifestyles in later ones.

Lead author Robert Smyth, a doctoral researcher at the University of Leicester, explained that early pterosaurs were highly specialized for climbing, with extreme modifications in their hands and feet, similar to those found in climbing lizards and birds like woodpeckers today. These early pterosaurs were likely restricted to arboreal habitats and consequently, small body sizes. However, a major evolutionary shift occurred during the Middle Jurassic period, when pterosaur hands and feet changed to look much more like those of ground-dwelling animals. These adaptations to ground-based movement opened up new ecological opportunities, leading to a wide variety of feeding strategies and allowing some pterosaurs to evolve to gigantic sizes.

Co-author Dr. David Unwin added that 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 became separated along the midline, allowing each hind limb to move independently. Combined with changes to their hands and feet, this innovation greatly improved pterosaurs’ mobility on the ground, freeing them from the constraints of climbing and allowing for their enormous growth.

The study also highlighted the importance of examining all aspects of pterosaur locomotion, not just flight, to fully understand their evolution. By exploring how they lived in the trees or on the ground, researchers can begin to understand the roles that pterosaurs played in ancient ecosystems.

When pterosaurs arrived on the ground, they cleverly avoided competition with other animals by exploiting ecological niches that required both flying and walking abilities. This led to the development of unique feeding strategies, such as evolving hundreds of fine, needle-like teeth for filter-feeding, similar to modern flamingos. This remarkable feature emerged at least 120 million years before the first flamingos evolved, showcasing the diverse and innovative adaptations of ancient pterosaurs.