Neotheropoda (meaning 'new theropods') is a clade that includes coelophysoids and more advanced theropod dinosaurs, and the only group of theropods who survived the Triassic–Jurassic extinction event. Yet all of the neotheropods became extinct during the early Jurassic period except for Averostra. Neotheropoda was named by Robert T. Bakker in 1986 as a group including the relatively advanced theropod subgroups Ceratosauria and Tetanurae. However, most later researchers have used it to denote a broader group. Neotheropoda was first defined as a clade by Paul Sereno in 1998 as Coelophysis plus modern birds, which includes almost all theropods except the most primitive species. The following family tree illustrates a synthesis of the relationships of the early theropod groups compiled by Hendrickx et al. in 2015.