Archosauria include two extant clades, crocodylians and avians. However, the diversification of the avian and crocodylian crown groups are relatively recent events that began during the Late Cretaceous (Brochu 2001, 2003; ...

The oldest archosauromorphs (dinosaurs, birds, crocodiles, and their stem-taxa) arerecorded in middle−upper Permian rocks, but it was not after the Permo−Triassic massextinction that the group shows a substantially high ...

Background: Archosauromorpha originated in the middle–late Permian, radiated during the Triassic, and gave rise to the crown group Archosauria, a highly successful clade of reptiles in terrestrial ecosystems over the last ...

The early evolution of archosauromorphs (bird- A nd crocodile-line archosaurs and stem-archosaurs) represents an important case of adaptive radiation that occurred in the aftermath of the Permo-Triassic mass extinction. ...

The anklebone (astragalus) of dinosaurs presents a characteristic upward projection, the 'ascending process' (ASC). The ASC is present in modern birds, but develops a separate ossification centre, and projects from the ...

The ornithosuchids were a group of archosaurs with body lengths ranging from 2 to 4 m recorded from Upper Triassic beds in Argentina and Scotland. The group was defined as a nodebased clade including Ornithosuchus longidens, ...

The pseudosuchian archosaur Ornithosuchus, from the Lossiemouth Sandstone Formation (Late Triassic), Scotland, was the first ornithosuchid to be discovered, and the only one recorded, in the northern hemisphere. The fossil ...

Riojasuchus tenuisceps Bonaparte 1967 is currently known from four specimens, includingtwo complete skulls, collected in the late 1960s from the upper levels of the Los ColoradosFormation (Late Triassic), La Rioja, Argentina. ...

The cranial anatomy of Neoaetosauroides engaeus Bonaparte, 1969 from the upper part of the Los Colorados Formation, western Argentina, is addressed herein. This description is based on material collected recently, which ...