A group of Argentine scientists studying the fossils of pisanosaurus found in the area of the Park Ischigualasto in Argentina. Scientists came to the conclusion that he is the link between the groups of ornithischian and saurischian. Article published in the journal Nature.
The first skeleton of pisanosaurus (badly damaged by erosion) was discovered in 1962 in the area of Agua de Las Katas (Agua de Las Catas) Ischigualasto formation. and 1967 it was described by paleontologist Rodolfo Casamiquela. The reptile was named in honor of Argentina.tion paleontologist Juan Pisano, and the species name Pisanosaurus mertii was in honor of the Mapuche naturalist Carlos Marti.
However, since the opening, Pisanosaurus mertii caused controversy about its phylogenetic position. Casamiquela believed that Pianosa belongs to the family pisanosaurus (which introduced the scientist himself), but in 1976 a group of paleontologists hypothesized that Pianosa belongs to the family heterodontosauridae. In 1991 Paul Sereno suggested that the new skeleton was a Chimera obtained during the overlay of the skeletons of different dinosaurs, and in 2008, Richard Butler and colleagues in his work on ornithischian phylogeny suggested that pisanosaurus is the earliest found bird-hipped species. Finally, in 2017 Federico Agnolin and Sebastian Rosadilla put forward the hypothesis that pisanosaurus belongs to the family of cilazapril. Salutary considered a dinosaur-like archosaurs, however, have in common with dinosaurs features.
Scientists led by Desejo Julia (Julia B. Desojo) from the University Nacional de La Plata in the new work decided to clarify this issue. During four expeditions from 2013 to 2019 paleontologists explored the countryside of Joiada del Cerro Las Lajas (Hoyada del Cerro Las Lajas) on the territory of the Ischigualasto formation . They found the remains of more than a hundred fossil tetrapod. Detailed stratigraphy of the 1000-meter layer gives high-precision chronostratigraphical picture of the Ischigualasto formation in Haaga del Cerro Las Lajas.