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A research team led by Dr. Lorenzo Marchetti of the Museum fur Naturkunde Berlin described the earliest archosauriform footprints (Pachychirotherium gardenaensis) from the GEOPARC Bletterbach - UNESCO World Heritage Dolomites, Italy. This study discovered that the transition from sprawling to erect locomotion was a stepwise process started in the late Permian and completed only by the Middle Triassic, leading shortly after to the acquisition of bipedality among the first dinosaurs and dinosaur relatives. This was published in the journal Palaeontology. Oct 15, 2026, 9:20:00 AM Dr. Gesine Steiner , Museum fur Naturkunde - Leibniz-Institut fur Evolutions- und Biodiversitatsforschung Archosaurs are iconic animals that ruled the Mesozoic, their most derived group being dinosaurs. Their direct ancestors, the archosauriforms, appeared during the late Permian. This was shortly before the catastrophic end-Permian extinction. However, their fossil record in the Permian is rather scattered. Additional information comes from their footprints, which have been first found in the GEOPARC Bletterbach - UNESCO World Heritage Dolomites, Italy. Until now, this material has been considered similar to Early Triassic archosauriform footprints such as Protochirotherium, known from Germany, Poland and Morocco. Also, it has been assumed that these footprints already indicated an erect stance while the animal walked. In the frame of a research project on archosauriform footprints carried out at the Museum fur Naturkunde Berlin , Dr. Lorenzo Marchetti, in collaboration with Hendrik Klein of Saurierwelt, re-analysed the material with the addition of some newly-described specimens. These footprints are now stored at the University La Sapienza of Rome and the Naturmuseum Sudtirol of Bozen (Italy). The scientists concluded that these specimen belong to the ichnofamily Chirotheriidae and are taxonomically different from all other footprints belonging to this group. So they named these footprints Pachychirotherium gardenaensis, meaning thick chirotheriid from Gardena.A comparative study on Pachychirotherium and on the feet and hands of archosauriforms based on morphology and measurements allowed an attribution of these footprints to archosauriforms, and more specifically Erythrosuchidae or animals with a very similar limb morphology. An additional analysis of archosauriform trackways from the Permian and Triassic revealed a stepwise transition from a sprawling posture (in the late Permian) to an erect posture (by the Middle Triassic) of these animals while walking. This happened together with an increase in cursoriality (so longer middle digits of the foot), digitigrady (so only the digits touched the ground) and a reduction in size of the hands. All of these features were essential for the later evolution of bipedality in dinosaurs and their close relatives. It is amazing to see how many details on the biology and locomotion of archosauriforms are preserved in fossil footprints, and this becomes even more important when the skeletons are scarce. In fact, trace fossils are the only fossils to directly register the locomotion of living animals says Dr. Lorenzo Marchetti of the Museum fur Naturkunde Berlin. Original Publication: Marchetti, L. and Klein, H. (2026), The new archosauriform track Pachychirotherium and the stepwise acquisition of digitigrady, cursoriality and erect stance in the group between the Permian and Triassic. Palaeontology, 69: e70089. https://doi.org/10.1111/pala.70089 Source: https://idw-online.de/de/news879161
