Diphydontosaurus is an extinct genus of small rhynchocephalian reptile from the Late Triassic of Europe.

[1] The skull, which was around 1.4 cm (0.55 in) long, had large orbits (eye sockets), as well as a combination of 17 regularly replaced conical pleurodont teeth on the front of the jaws and 11 larger permanent acrodont teeth in the posterior jaws.

[2] Diphydontosaurus avonis is known from abundant remains covering most of the skeleton found in fissure fill deposits in Southwest Britain.

[1] A skeleton of a juvenile sphenodontian tentatively referred to Diphydontosaurus was reported in 1996 from the Norian of Lombardy in Italy.

In the Late Triassic, the regions that Diphydontosaurus lived in were numerous rocky, small caves, that sat on a limestone bed.