Paratypothorax

Paratypothorax is an extinct genus of aetosaur. It was large, reaching up to 3 meters in length, and covered with scutes marked by ridges and bumps. During the Norian, Paratypothorax shared the same range as Aetosaurus. Paratypothorax survived right up until the Rhaetian age (Apachean land fauna zone).

Paratypothorax is a typothoracisine aetosaur, and a member of the clade Paratypothoracisini. Members of this clade are characterized by paramedian plates that are much wider than long, have a distinct radial patterning, sharp anteromedial and anterolateral projections, a smooth anterior bar, and a medially offset dorsal eminence or boss.

Paratypothorax is also known from Greenland and the western United States. The best skeleton from the Chinle Formation was collected from Petrified Forest National Park by the Field Museum in 1982. The Petrified Forest specimen was described by Hunt and Lucas (1992) and again by Lucas et al. (2006) who assign it to Paratypothorax andressorum; however, this ID has not been accepted by all workers (e.g., Long and Murry, 1995) who suggest that it may be a new taxon.

The holotype specimen, which consists solely of armor, has never been completely described.