Changes in the tree canopy facilitated the evolution of the gliding reptile

Researchers combed through near-perfect fossils of the world’s first gliding reptile with a fine-toothed comb and unravel previously unknown facets discover that it was a change in the tree canopy that likely facilitated such flight in these creatures.

From the first fossils of Coelurosauravus elivensis were discovered in 1907, there has been heated debate about how the animal actually lived during the late Permian, between 260 and 252 million years ago, and how its unique parts of the bodies fit together.

By gathering enough fossils to create a near-perfect skeletal reconstruction, new research is providing new insights into the tetrapod’s morphology and habits. and crucially establishes how it became the first known reptile to hover.

The answer to this last question stems from the canopy of the forest in which this unusual creature lived – suggest experts from the Muséum national d’Histoire naturelle de Paris (or National Museum of Natural History) and the Staatliches Museum für Naturkunde Karlsruhe, in Germany.

Explain their findings, today, in the peer-reviewed report Journal of Vertebrate Paleontology, lead author Valentin Buffa, from the Center de Recherche en Paléontologie, Paris at the French Museum of Natural History, states: “The forests of Pennsylvania, although taxonomically and vertically heterogeneous, had rather open canopy strata with spatially separated tree taxa , which resulted in little crown overlap. In contrast, cisular forests show evidence of denser communities suggesting more continuous canopy strata. Such a change in forest structure might explain why no gliders were reported before weigeltisaurids, although several arboreal or scansorial amniotes have been described from Pennsylvanian and cisular deposits. These dragons weren’t forged in mythological fire – they just needed to move from place to place. Gliding was found to be the most efficient mode of transport and here in this new study we see how their morphology enabled this.

The team examined three known fossils of C. elivensis, as well as a number of related specimens, all belonging to the family Weigeltisauridae. Their research focused on the post-cranial part – the body, including the torso, limbs and a remarkable gliding apparatus, known as the patagium. The latter is the membranous flap covering the fore and hind limbs, also present in living animals such as flying squirrels, sugar gliders and colugos.

Previous analysis of the reptile had assumed that its patagium was supported by bones that extended from the ribs, as they do in the modern world. Draco species from Southeast Asia – which to this day amazes observers with its gliding flights between the trees of the rainforest it inhabits.

However, this new in-depth examination suggests that the patagium of C. elivensis either extended from the gastralia—an arrangement of bones in the skin that covers the bellies of some reptiles, including crocodilians and dinosaurs—or from the musculature of the trunk. This would mean that the gliding apparatus sat lower on the abdomen than in modern gliding lizards.

By combining this finding with other derivatives of bone structure seen in fossils, the researchers offered a more refined view of how this agile creature moved in its arboreal habitat.

“Sharp, curved claws and a compressed body shape support the idea that was perfectly suited to moving tree trunks vertically upwards. The similarity in length of the fore and hind limbs further indicates that it was an expert climber – their proportional length helped it stay close to the surface of the tree, preventing it from pitching and losing its balance. Its long, lean body and whip-like tail, also seen in contemporary arboreal reptiles, further support this interpretation,” adds Buffa.

And as for its resemblance to Draco?

C. elivensis bears a striking resemblance to the contemporary genre Draco“, says Boufa. “Although its habits are probably similar to those of its modern counterpart, we do however see subtle differences.

“As Draco lizards, Coelurosauravus was able to grasp its patagium with its front claws, stabilize it during flight, and even adjust it, allowing greater maneuverability. An extra knuckle in one finger, however, may have enhanced this ability. This may have been a necessary compensation for the lower positioning of the patagium, which probably made it more unstable.

– This press release was provided by the Taylor & Francis Group

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