The skull of Teyujagua is exceptionally well preserved and almost complete, possessing several key features of the archosauriform skull.
In total it measures approximately 115 millimetres (4.5 in), with a long, broad and flattened snout.
Teyujagua possesses a mosaic of characteristics intermediate between basal archosauromorphs and Archosauriformes.
Primitive features include the absence of an antorbital fenestra and an open lower temporal bar, however like Archosauriformes it has serrated teeth and an exposed mandibular fenestra on the lower jaw, features previously only found in Archosauriformes.

The external nares are dorsally positioned and fused into a single large opening (confluent), a feature found in several aquatic and semi-aquatic Archosauriformes, although the orbits are positioned laterally and slightly forwards, providing limited binocular vision.
The nasals are long and occupy much of the skull length, followed by short, broad frontals that are almost excluded from the margin of the orbit by the pre- and postfrontals.
The postfrontal bones are sculpted, and the jugals are similarly adorned with longitudinal ridges.
The parietal bones surround a small pineal foramen ("third eye"), a feature absent in most archosauriforms but sometimes found in the proterosuchid archosauriform Proterosuchus.
The lower temporal fenestra is trapezoidal in shape, another characteristic previously on found in archosauriforms, while the upper temporal fenestrae are slender.

A unique feature (autapomorphy) of Teyujagua is that the external mandibular fenestra is positioned unusually far forward on the lower jaw, directly beneath the eyes when the jaw is closed.
The dentition is heterodont, bearing four small premaxillary teeth and a maximum of 15 larger maxillary teeth.
The dentary tooth row is slightly shorter than the tooth row of the maxilla.
The teeth are all laterally compressed and serrated, however unlike later Archosauriformes they are only serrated on their distal (rear) margins.
The teeth are also unlike early archosauriform teeth in that they are loosely implanted in deep sockets (thecodont), whereas the earliest archosauriforms had teeth fused to their bony sockets (ankylothecodont).
The skull of Teyujagua is exceptionally well preserved and almost complete, possessing several key features of the archosauriform skull. In total it measures approximately 115 millimetres (4.5 in), with a long, broad and flattened snout. Teyujagua possesses a mosaic of characteristics intermediate between basal archosauromorphs and Archosauriformes. Primitive features include the absence of an antorbital fenestra and an open lower temporal bar, however like Archosauriformes it has serrated teeth and an exposed mandibular fenestra on the lower jaw, features previously only found in Archosauriformes.
The external nares are dorsally positioned and fused into a single large opening (confluent), a feature found in several aquatic and semi-aquatic Archosauriformes, although the orbits are positioned laterally and slightly forwards, providing limited binocular vision. The nasals are long and occupy much of the skull length, followed by short, broad frontals that are almost excluded from the margin of the orbit by the pre- and postfrontals. The postfrontal bones are sculpted, and the jugals are similarly adorned with longitudinal ridges. The parietal bones surround a small pineal foramen ("third eye"), a feature absent in most archosauriforms but sometimes found in the proterosuchid archosauriform Proterosuchus. The lower temporal fenestra is trapezoidal in shape, another characteristic previously on found in archosauriforms, while the upper temporal fenestrae are slender.
A unique feature (autapomorphy) of Teyujagua is that the external mandibular fenestra is positioned unusually far forward on the lower jaw, directly beneath the eyes when the jaw is closed. The dentition is heterodont, bearing four small premaxillary teeth and a maximum of 15 larger maxillary teeth. The dentary tooth row is slightly shorter than the tooth row of the maxilla. The teeth are all laterally compressed and serrated, however unlike later Archosauriformes they are only serrated on their distal (rear) margins. The teeth are also unlike early archosauriform teeth in that they are loosely implanted in deep sockets (thecodont), whereas the earliest archosauriforms had teeth fused to their bony sockets (ankylothecodont).
Teyujagua