Stenaulorhynchus (possibly meaning "narrow tube beak") is an extinct genus of hyperodapedontid rhynchosaur known from the Middle Triassic (late Anisian stage) deposits of Tanganyika Territory, Tanzania.

The type species is Stenaulorhynchus stockleyi, a beaked herbivore measuring 1–6 meters in length.

Over time, the surfaces of the jaw bones would erode as well, causing the maxillary grooves to become shallower and more rounded.

[1] Microscopic analysis of thin-sections of bone have shown that Stenaulorhynchus had a determinant growth pattern, reaching 2/3 of their adult size within one year.

[2] It would have grown slower than archosauriformes, the South American rhynchosaur species, saurischian dinosaurs, and birds.

[1] While Stenaulorhynchus is the dominant vertebrate in the Manda beds, they also included a Dicynodont and vertebrae from an unidentified Theropod.

[1][5] Haughton also described a species which he named Stenaulorhynchus major, which he said differed primarily in size, based on a distal left and right humerus fragments.

[10] Stenaulorhynchus shares characteristics with other early rhynchosaurs, including their ankylothecodont dentition (teeth within deep sockets and fused to the bone) and precision-shear bite.

Based on an analysis of morphological characteristics, one study defines it as including all taxa that are more closely related to Stenaulorhynchus stockleyi than Hyperodapedon gordoni.

[7] Stenaulorhynchus has also been labeled as a sister-taxa to the Brazilian genus Brasinorhynchus which also has three or more tooth rows medial to the main maxillary groove but lacks the centrum contribution to the parapophyses and diaphophyses.

[1][7] Stenaulorhynchus is found in the Upper Bone Bed in the Njalili locality, part of the Lifua Member of the Manda Formation.

Rises in precipitation and mean annual temperature may have led to an increase in perennial vegetation, as well.