Are these small Triassic reptiles the missing link to the ancestors of pterosaurs?

Nature · Published 3 October 2026 Swipe more like this →

In short: Lagerpetids were once considered the earliest dinosaurs, but recent fossil discoveries have completely rewritten their family tree. These lightly-built, Triassic-era creatures are now increasingly viewed as the closest relatives to the flying pterosaurs, helping scientists bridge a mysterious gap in the evolution of ancient, winged reptiles.

Lagerpetidae, a family of basal avemetatarsalians, has long challenged paleontologists. First described by Alfred Sherwood Romer in 1971 based on specimens from Argentina, these animals were traditionally classified as dinosauromorphs—early relatives of dinosaurs. This view persisted from the 1980s through the 2010s, with researchers like Arcucci, who named the group Lagerpetonidae in 1986, and later S. J. Nesbitt, who updated the name to Lagerpetidae in 2009. However, the classification remains a subject of intense scientific debate.

The narrative shifted dramatically in 2020. New fossils of the jaw, forelimbs, and braincase led researchers including Kammerer, Ezcurra, and Baron to propose that lagerpetids are actually the sister clade to Pterosauria. This reclassification suggests they are pterosauromorphs rather than dinosauromorphs. Further complicating the picture, a 2025 study by Garcia and Müller suggested that lagerpetids might represent a paraphyletic grade leading toward pterosaurs, effectively closing a 'ghost lineage' that previously separated pterosaurs from their precursors. In this model, taxa like Venetoraptor are identified as the closest relatives to pterosaurs.

Physically, lagerpetids were small, lightly-built animals known primarily from their distinctive hindlimbs. Their anatomy features a unique, enlarged crista tibiofibularis on the femur and a fused astragalus and calcaneum in the ankle, traits that mirror those found in pterosaurs and some early dinosaurs. While they possessed small, dense teeth, some species also exhibited a toothless snout region, potentially forming a beak. These fossils have been unearthed across a wide geographic range, including Argentina, the United States, Brazil, India, and Madagascar, providing a global window into the complex evolutionary transitions of the Triassic period.

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