Tetraodontiform

Evolution

Traditionally, the oldest recognized tetraodontiforms are the extinct suborder Plectocretacicoidei from the Late Cretaceous (Santonian to Campanian) of Italy and Slovenia, both in the former Tethyan region. These comprise the families Cretatriacanthidae and Protriacanthidae. Plectocretacicus from the Cenomanian of Lebanon has also been proposed as a tetraodontiform, but this has been more recently questioned. More recent studies have also questioned the placement of the Plectrocretacicoidei in the Tetraodontiformes, due to their ancient nature contrasting with the position of the Tetraodontiformes as the most derived percomorph lineage, and the group displaying many traits that are not present in modern tetraodontiforms or are not exclusively found in them. It has thus been suggested that the Plectocretacicoidei might either represent indeterminate percomorphs or basal members of a more inclusive Acanthuriformes. If the Plectocretacicoidei are excluded, the earliest definitive fossil tetraodontiforms are a number of genera known from the earliest Eocene.