A new study by palaeontologists from the Universities of Leicester, Birmingham, and Liverpool John Moores University shows that pterosaur limbs had an unexpectedly high degree of variation, comparable to that observed in living birds. The discovery demonstrates that pterosaurs were not limited to a life in the air but were also adapted to a wide range of terrestrial lives, from tree-climbing in early species to more terrestrial lives in later species.
Pterosaurs have adapted to a surprisingly wide range of non-aerial locomotion ecologies. Early small, long-tailed pterosaurs (not pterosaurs) showed extreme changes in hand and foot proportions, indicating a climbing lifestyle. In contrast, the hands and feet of later short-tailed pterosaurs (Pterosaurians) typically exhibit morphologies consistent with a more ground-based locomotor ecology. (A) Non-pterosaur antiquities restoration Scaphognathus crassirostris (Late Jurassic) in scansorial mode, with autosufficiency characterized by short proximal elements and elongated distal elements. (B) Restoration of Pterodactylis-type antiquities Balaenognathus maeuseri (Late Jurassic) In the terrestrial mode, the autopodia are characterized by an elongated proximal element and a shortened distal element. (C) Reconstruction of Scaphognathus (left) and Baleonognathus (Right) Rear view showing major flight surfaces. (D) Simplified pterosaur phylogeny showing the major taxa used in the study. Image credit: Smith others., doi: 10.1016/j.cub.2024.09.014.
Pterosaurs, the first true flying vertebrates, played an important role in Mesozoic terrestrial ecosystems.
However, our current understanding of their terrestrial locomotion abilities, and more broadly their terrestrial paleoecology, is limited.
Robert Smith, a postdoctoral researcher at the University of Leicester, said: “Early pterosaurs were highly specialized for climbing and had extreme modifications to their limbs, similar to those seen in today’s climbing lizards and birds such as woodpeckers. It’s the same,” he said.
“Holding on to a vertical surface with your fingertips for long periods of time is a difficult task, but it’s much easier for smaller, lighter animals.”
“These early pterosaurs were likely restricted to arboreal habitats, and as a result, their body size was small.”
“However, during the mid-Jurassic period, a major evolutionary change occurred, and pterosaurs’ hands and feet changed to more closely resemble those of land-dwelling animals.”
“These adaptations to terrestrial locomotion have opened up new ecological opportunities and given rise to a wide variety of feeding strategies.”
Freed from the size constraints imposed by vertical living, some pterosaurs were able to evolve to gigantic sizes with wingspans of up to 10 meters.
Dr David Unwin, a researcher at the University of Leicester, said: “In early pterosaurs, the hind limbs were connected by a flight membrane, which severely hindered walking and running.”
“In later, more advanced pterosaurs, this membrane separated along the midline, allowing each hindlimb to move independently.”
“This was an important innovation, and together with the changes in the hands and feet, it greatly increased the maneuverability of pterosaurs on land.”
“These later pterosaurs were freed from the constraints of climbing and were able to grow to enormous sizes, making some species the true giants of the Mesozoic Era.”
In early pterosaurs, the bones at the base of the fingers and toes were relatively short, and the parts farther from the body were very long, terminating in large, curved claws. These improvements created a strong grip, making it ideal for climbing trees.
In contrast, later, more evolved pterosaurs showed the opposite pattern. That is, the bones at the base of the fingers and toes were much longer, and those closer to the tips were shorter.
Their claws are also flatter and less curved, suggesting they are better suited for walking than climbing.
“These discoveries highlight the need to examine all aspects of pterosaur locomotion, not just flight, to fully understand pterosaur evolution. It’s just part of our history,” Smith said.
“By studying how they lived in trees and on the ground, we can begin to understand the role they played in ancient ecosystems.”
“When pterosaurs arrived on Earth, it was already inhabited by a wide range of animals, including dinosaurs and many other reptiles.”
“Pterosaurs cleverly avoided competition with these established groups by exploiting ecological niches that required both the ability to fly and walk.”
“This resulted in some strange feeding strategies, including the evolution of hundreds of thin, needle-like teeth used for filter feeding.”
“This surprising feature is similar to the feeding method of modern flamingos and appeared at least 120 million years before the first flamingos evolved.”
of study Published in a magazine current biology.
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Robert S.H. Smith others. Morphology of limbs showing the invasion of terrestrial environments by pterosaurs in the mid-Mesozoic era. current biologypublished online on October 4, 2024. doi: 10.1016/j.cub.2024.09.014
Source: www.sci.news
