 This study combined with others from Texas suggest that hybodonts were well established, and in some places dominant, during the Permian.In general, the Permian record of hybodonts is limited.It was initially hypothesized that hybodont diversity was not significantly impacted by the end-Permian extinction, instead it was thought that diversity of Permian hybodonts declined over the 50 million years before the end-Permian extinction.