Averostra

Averostra, or "bird snouts", is a clade that includes most theropod dinosaurs that have promaxillary fenestrae, an extra opening in the bone that makes up the upper jaw.

Definition
Averostra was named by Gregory S. Paul in 2002 as an apomorphy-based clade defined as all theropods with a promaxillary fenestra. It was later re-defined by Ezcurra and Cuny in 2007 at a node-based clade containing Ceratosaurus nasicornis, Allosaurus fragilis, their common ancestor and all its descendants.