Paleontologists have created the first accurate skeletal reconstruction of Scleromochlus taylori, a small species of reptile that lived during the Triassic period, some 230 million years ago. Their results reveal new anatomical details that conclusively identify Scleromochlus taylori as a close pterosaur relative.
Pterosaurs, the first vertebrates to evolve powered flight, were key components of Mesozoic terrestrial ecosystems from their sudden appearance in the Late Triassic epoch until their demise at the end of the Cretaceous.
However, the origin and early evolution of pterosaurs are poorly understood owing to a substantial gap between these reptiles and their closest relatives, lagerpetids (family Lagerpetidae).
Scleromochlus taylori, a tiny reptile from the Late Triassic of Scotland discovered over a century ago, was hypothesized to be a key species closely related to pterosaurs.
The ancient creature belongs to Pterosauromorpha, a group that includes lagerpetids and pterosaurs.
“Living approximately 240-210 million years ago, lagerpetids were a group of relatively small (cat or small dog-sized) active reptiles,” said Dr. Davide Foffa, a paleontologist at the University of Birmingham, and colleagues.
“Scleromochlus taylori was smaller still at under 20 cm (7.9 inches) in length.”
“Our results support the hypothesis that the first flying reptiles evolved from small, likely bipedal ancestors.”
There had previously been disagreement as to whether Scleromochlus taylori represented an evolutionary step in the direction of pterosaurs, dinosaurs or else some other reptilian offshoot.
The fossil is poorly preserved in a block of sandstone, which has made it difficult to study in sufficient detail to properly identify its anatomical features.
“It’s exciting to be able to resolve a debate that’s been going on for over a century, but it is far more amazing to be able to see and understand an animal which lived 230 million years ago and its relationship with the first animals ever to have flown,” Dr. Foffa said.
“This is another discovery which highlights Scotland’s important place in the global fossil record, and also the importance of museum collections that preserve such specimens, allowing us to use new techniques and technologies to continue to learn from them long after their discovery.”
“Pterosaurs were the first vertebrates to evolve powered flight and for nearly two centuries, we did not know their closest relatives,” said Virgina Tech’s Professor Sterling Nesbitt.
“Now we can start filling in their evolutionary history with the discovery of tiny close relatives that enhance our knowledge about how they lived and where they came from.”
The results are reported in a paper in the journal Nature.
D. Foffa et al. Scleromochlus and the early evolution of Pterosauromorpha. Nature, published online October 5, 2022; doi: 10.1038/s41586-022-05284-x
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