It is known from four specimens, each consisting of a partial lower jawbone collected from the Wonthaggi Formation at Flat Rocks, Victoria, Australia.

[1] Teinolophos is deeply divergent within monotreme evolution, so in 2022 it was proposed to move it into its own family, Teinolophidae.

The dentary is about one sixth the size of Steropodon's, and wear facets indicate an "orthal" occlusion with the upper molars.

[1] Unlike modern monotremes, which have suspended ear bones much like placentals and marsupials, Teinolophos still had them connected to the jaw via the Meckel's cartilage.

This reinforces the idea that the modern ear condition evolved independently among monotremes and therians.