A new study explores how pterosaurs transitioned from small tree-dwellers to enormous flying giants. These flying reptiles first descended from trees during the mid-Jurassic Period, paving the way for species with wingspans of 10 meters.
Palaeontologists at the University of Leicester have identified the evolutionary changes that enabled pterosaurs to grow to impressive sizes.
The research uncovered that their capacity for efficient ground movement was vital in influencing the maximum size of these impressive flying creatures, some of which had wingspans reaching up to 10 meters.
A publication released today (4 October) in Current Biology details the work of a team led by the University of Leicester, who examined the feet and hands of pterosaurs from various regions and eras.
The study revealed an unexpected degree of diversity, akin to that seen in modern birds. This finding suggests that pterosaurs were not limited to aerial life but also adapted to various ground-based lifestyles, ranging from climbing in earlier varieties to more terrestrial behaviors in their later relatives.
Pterosaurs, recognized as the first true flying vertebrates, exhibit some of the most extraordinary evolutionary adaptations throughout history. Although they are primarily known for gliding through Mesozoic skies (252-66 million years ago), this research highlights significant diversity in their terrestrial habitats when they were not airborne.
Robert Smyth, lead author and doctoral researcher in the Centre for Palaeobiology and Biosphere Evolution at the University of Leicester, stated: “Early pterosaurs were expertly evolved for climbing, featuring highly specialized hands and feet, similar to climbing lizards and modern woodpeckers. Maintaining a grip on vertical surfaces for long periods is challenging—especially for small, lightweight species.”
Initially, these early pterosaurs were likely limited to living in trees due to their small sizes. However, a major evolutionary transformation occurred during the Middle Jurassic period, leading to alterations in pterosaur limbs to resemble those of ground-dwelling creatures. These newfound adaptations for moving on land opened up various ecological roles, allowing some pterosaurs to break free from size constraints and reach colossal dimensions with 10-meter wingspans.
Co-author Dr. David Unwin from the University of Leicester noted: “In primitive pterosaurs, the hind limbs were attached by a flight membrane, which hindered walking and running. In more advanced pterosaurs, this membrane split along the centerline, permitting independent movement of each hind limb. This innovation, coupled with changes in their hands and feet, significantly enhanced their mobility on the ground.
“Freed from the limitations of climbing, these later pterosaurs could attain remarkable sizes, with some evolving into the giants of the Mesozoic.”
The structure of their hands and feet provides valuable clues. In early pterosaurs, the bones closest to the fingers and toes were relatively short, while those farther away were elongated, ending in large curved claws. This configuration afforded them a strong grip, ideal for climbing. Conversely, more advanced pterosaurs displayed longer basal bones and shorter terminal ones, with flatter, less curved claws indicating better adaptations for walking instead of climbing.
Robert Smyth further commented: “These discoveries highlight the importance of studying all aspects of how pterosaurs moved—not only their flying abilities—to truly grasp their evolution. Their ability to fly is merely one facet of their narrative. By analyzing how they lived both in trees and on land, we can gain insight into their ecological roles in ancient environments.”
When pterosaurs ventured onto land, they entered an ecosystem already inhabited by a variety of animals, including dinosaurs and other reptiles. They smartly avoided direct competition with these existing groups by adapting to specific ecological roles that utilized both their flying and walking capabilities. This led to the development of unusual feeding strategies, such as evolving hundreds of fine, needle-like teeth for filter-feeding— a characteristic seen 120 million years before the first flamingos appeared.
