Ground movement pivotal in allowing Pterosaurs to become giants

Ground movement pivotal in allowing Pterosaurs to become giants
by Sophie Jenkins
London, UK (SPX) Oct 04, 2024

New research from the Centre for Palaeobiology and Biosphere Evolution at the University of Leicester has shed light on the evolutionary adaptations that allowed ancient pterosaurs to reach enormous sizes. A key finding of the study is that efficient movement on the ground played a critical role in how large these flying reptiles could grow, with some species achieving wingspans of up to 10 meters.

The study, published in 'Current Biology' on October 4, explores the evolution of pterosaur hands and feet. Researchers from the University of Leicester examined fossilized remains of pterosaurs from around the world, revealing a surprising variation in their limb structure, similar to what is observed in modern birds. This variation suggests that pterosaurs were not solely adapted for flight but also evolved to live in diverse terrestrial environments, shifting from early tree-dwelling species to later, ground-dwelling giants.

"Early pterosaurs were highly specialized for climbing, with modifications in their hands and feet similar to those found in climbing animals today," explained Robert Smyth, lead author and doctoral researcher at the Centre for Palaeobiology and Biosphere Evolution. He added that these early adaptations limited their size, as climbing is more manageable for smaller animals. However, during the Middle Jurassic period, pterosaurs evolved features more suited to ground movement, allowing for greater body size and diverse feeding strategies.

Dr. David Unwin, a co-author of the study, pointed out that early pterosaurs had flight membranes connecting their hind limbs, which restricted ground mobility. In later species, the separation of these membranes allowed for independent limb movement, significantly enhancing their ability to walk and run. "Freed from the constraints of climbing, these later pterosaurs could grow to enormous sizes, becoming true giants of the Mesozoic," he said.

The research team noted that early pterosaur fingers and toes were well-adapted for gripping vertical surfaces, a necessity for tree-climbing species. Over time, these features evolved, with later species showing longer finger and toe bones at the base and flatter, less curved claws, indicating a shift toward walking.

Smyth emphasized the importance of studying all aspects of pterosaur locomotion: "That pterosaurs could fly is only part of their story. By exploring how they lived in the trees or on the ground, we can better understand their roles in ancient ecosystems."

Pterosaurs avoided competition with other animals like dinosaurs by occupying ecological niches that required both flying and walking skills. This dual adaptation led to unusual feeding strategies, including the development of needle-like teeth for filter-feeding, a method that evolved millions of years before similar adaptations in modern flamingos.

Research Report:'Hand and foot morphology maps invasion of terrestrial environments by pterosaurs in the mid-Mesozoic'