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Archosaurs are a subgroup of archosauriforms, which themselves are a subgroup of archosauromorphs. Both the oldest archosauromorph (Protorosaurus speneri) and the oldest archosauriform (Archosaurus rossicus) lived in the late Permian. The oldest true archosaurs appeared during the Olenekian stage (247–251 Ma) of the Early Triassic.
Extinct archosaurs include non-avian dinosaurs, pterosaurs, and extinct relatives of crocodilians. Modern paleontologists define Archosauria as a crown group that includes the most recent common ancestor of living birds and crocodilians, and all of its descendants.
This left crocodilians and birds as the two surviving archosaur groups. [56] A series of phylogenetic analyses in the late 1980s and 1990s strongly supported the proposal of Gow (1975). [54] [57] [53] [58] [59] Tanystropheus, Macrocnemus, Protorosaurus, and Prolacerta were always placed as members of Archosauromorpha, closer to archosaurs than ...
Figure 1:In mammals, the quadrate and articular bones are small and part of the middle ear; the lower jaw consists only of dentary bone.. While living mammal species can be identified by the presence of milk-producing mammary glands in the females, other features are required when classifying fossils, because mammary glands and other soft-tissue features are not visible in fossils.
Dinosaurs belong to a group known as archosaurs, which also includes modern crocodilians. Within the archosaur group, dinosaurs are differentiated most noticeably by their gait. Dinosaur legs extend directly beneath the body, whereas the legs of lizards and crocodilians sprawl out to either side. [29]
"Rauisuchia" is a paraphyletic group of mostly large and carnivorous Triassic archosaurs. [2] Rauisuchians are a category of archosaurs within a larger group called Pseudosuchia, which encompasses all archosaurs more closely related to crocodilians than to birds and other dinosaurs. First named in the 1940s, Rauisuchia was a name exclusive to ...
Today, October 1, Ancestry is launching a new Know Your Pet DNA test that provides information about future health issues dogs could face based on their unique genetic makeup.
A clade of diapsid reptiles that developed from archosauromorph ancestors some time in the Late Permian (roughly 250 million years ago).It was defined by Jacques Gauthier (1994) as the clade stemming from the last common ancestor of Proterosuchidae and Archosauria (the group that contains crocodiles, pterosaurs and dinosaurs (including birds); [1] Phil Senter (2005) defined it as the most ...