Neotheropoda

Skeleton of Coelophysis, one of the first Neotheropoda, in London's Natural History Museum.

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The Neotheropoda are a group within the theropod dinosaurs. It includes all the advanced theropods including Ceratosauria and Tetanurae, but includes some very original forms from such as Eoraptor and the Herrerasauridae. This very original shapes lacks many of the bird-like features, which distinguishes the Neotheropoda.

This is controversial, which can be this original forms actually classified within the Theropoda: For example, here Langer ( 2004) Guabeisaurus as the only form that is indeed attributable to theropods, but outside the Neotheropoda stands while outside forms such as Eoraptor and the Herrerasauridae classified the theropods. Sereno (1999 ), however, assigns a Eoraptor and the Herrerasauridae within the Theropoda and outside the Neotheropoda.

This article covers the taxon Neotheropoda from a phylogenetic point of view - for further information regarding the characteristics and biology of these animals see the main article theropods.

Temporal classification

The oldest Neotheropoda date from the late Carnium ( Upper Triassic, 228 million years ago ), and include, for example Coelophysis bauri with a. As today's birds are descended from dinosaurs neotheropoden, close the Neotheropoda from a phylogenetic point of view the birds with a. The last non- avian Neotheropoda died out about 65.5 million years ago during the mass extinction at the Cretaceous - Tertiary boundary.

Definition and synapomorphies

The taxon Neotheropoda was erected in 1986 by Robert Bakker. It is defined as a node-based taxon (node- based definition) that the last common ancestor of Coelophysis bauri and Passer domesticus ( House Sparrow ) and includes all descendants of this ancestor with.

The Neotheropoda can be distinguished from more primitive forms by numerous shared derived characteristics ( synapomorphies ). Examples are the lacrimal bone ( lacrimal ), the large area of the skull top is revealed, as well as the sacrum, composed of five sacral vertebrae. The second finger is the longest in the hand, also the penultimate phalanx ( claw not counted) is the longest.

System

It follows a recent cladogram example, simplified according to Nesbitt and colleagues ( 2009):

Staurikosaurus

Herrerasaurus

Chindesaurus

Eoraptor

Tawa

Neotheropoda

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