Table of Contents
Is an Archosaur a dinosaur?
Archosaurs (“ruling reptiles”) are members of a subclass that also includes the dinosaurs, the pterosaurs (flying reptiles), and several groups of extinct forms, mostly from the Triassic Period (251 million to 200 million years ago).
Are crocodiles archosaurs?
Crocodilians and birds are the two extant clades of archosaurs, a group that includes the extinct dinosaurs and pterosaurs. Fossils suggest that living crocodilians (alligators, crocodiles, and gharials) have a most recent common ancestor 80 to 100 million years ago.
Are birds archosaurs and dinosaurs?
About 250 million years ago, the archosaurs split into two groups: a bird-like group that evolved into dinosaurs, birds, and pterosaurs, and a crocodile-like group that includes the alligators and crocs alive today and a diversity of now-extinct relatives.
Did archosaurs evolve dinosaurs?
Dinosaurs evolved from other reptiles (socket-toothed archosaurs) during the Triassic period, over 230 million years ago. Dinosaurs evolved soon after the Permian extinction, which was the biggest mass extinction that ever occured on Earth.
What are the archosaurs ancestors of?
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.
Is a ostrich an Archosaur?
Living archosaurs comprise birds (dinosaurs), and their sister group, the crocodilians. Archosaurs appeared in fossil record sometime in the Triassic and are thought to have evolved ears sensitive to airborne sound sometime later. Palaeognaths are generally flightless and include such birds as the ostrich.
Are archosaurs still alive?
Archosauria ( lit. ‘ruling reptiles’) is a clade of diapsids, with birds and crocodilians as the only living representatives. Extinct archosaurs include non-avian dinosaurs, pterosaurs, and extinct relatives of crocodilians.
Is an ostrich an Archosaur?
Are turtles archosaurs?
“We show that turtles share a more recent common ancestor with birds and crocodilians — a group known as archosaurs — than with lizards and snakes.” Field and collaborators report their findings May 5 in the journal Evolution and Development. Reptiles comprise a vast animal group of more than 20,000 species.
Are snakes archosaurs?
‘ruling reptiles’) is a clade of diapsids, with birds and crocodilians as the only living representatives. Archosaurs are broadly classified as reptiles, in the cladistic sense of term which includes birds….Archosaur.
| Archosaurs Temporal range: Earliest Triassic–Present, | |
|---|---|
| Clade: | Eucrocopoda |
| Clade: | Archosauria Cope, 1869 |
| Subgroups |
Are tetrapods archosaurs?
Archosaurs can traditionally be distinguished from other tetrapods on the basis of several synapomorphies, or shared characteristics, which were present in their last common ancestor.
Which is the best description of an archosaur?
Archosaur. Archosaur, (subclass Archosauria), any of various reptiles, including all crocodiles and birds and all descendants of their most recent common ancestor. Archosaurs (“ruling reptiles”) are members of a subclass that also includes the dinosaurs, the pterosaurs (flying reptiles), and several groups of extinct forms,…
When did the first archosaur appear on Earth?
The first known archosaurs appeared in the Middle Triassic Period (about 246 million to 229 million years ago). They evolved from an earlier group of diapsid reptiles, diapsids having two openings in the skull behind the eye.
Archosaurs are a true, monophyletic clade, that is to say that all archosaurs are the descendents of a single common ancestor, and all of the descendants of that ancestor are considered archosaurs. That may sound unnecessarily circular, but it is important.
Which is the second branch of the archosaur family?
The second archosaurian branch, the Ornithosuchia, includes birds and all archosaurs more closely related to birds than to crocodiles. In addition to the dinosaurs (the group from which birds evolved and to which they formally belong), ornithosuchians include pterosaurs and some extinct Triassic forms such as lagosuchids and lagerpetontids.