Decuriasuchus quartacolonia (França, Ferigolo and Langer 2011) Ladinian, Middle Triassic ~240 mya, 2.6m in length was found in an association of nine skeletons indicating the first evidence of gregarious behavior in the archosauriformes (but note that the much more primitive and earlier Youngina (SAMK 7710) was found in a similar assembly.
The original report nested Decuriasuchus with two rauisuchians, Prestosuchus and Batrachotomus, probably because Vjushkovia and Pseudhesperosuchus, among others, were excluded from that analysis. Here, as part of a larger inclusion set, Decuriasuchus nested as the basalmost Protoarchosauria, a taxon preceding the Archosauria. Derived from a sister to Vjushkovia and Yarasuchus, Decuriasuchus phylogenetically preceded Pseudhesperosuchus and Lewisuchus along with Turfanosuchus near the base of the Archosauria.
Distinct from Vjushkovia the skull of Decuriasuchus had a longer, lower profile with a smaller naris, smaller antorbital fenestra, smaller orbit and smaller lateral temporal fenestra. The upper temporal fenestra was longer and the parietal crest was higher. The subnarial fenestra was more distinct. A small bump topped the nasals. The premaxilla was smaller. The maxilla was longer and ventrally straighter. The antorbital fossa was much larger than the antorbital fenestra. The postorbital was more robust and invaded the orbit. The jugal did not descend as much. The quadratojugal and squamostal created a strong V shape nearly bisecting the lateral temporal fenestra. The squamosal included a secondary descending process at the occiput. The mandibular fenestra was larger.
The cervicals were longer and the neural spines were shorter. The presacral count increased to 26. The dorsal ribs were more gracile. The caudal neural spines were taller.
The scapula and coracoid were smaller. The humerus was more gracile.
The ilium was shorter. The pubis and ischium were both longer. The femur was slightly longer. The metatarsals were longer than the digits and more similar to one another in length. Metatarsal IV was narrower than mt III. Metatarsal V was strongly hook-shaped and robust. The calcaneum was short and the heel was proximally directed.