The Pterygometopidae are a family of trilobites, that is known from the Floian to the Katian (Ordovician), and reappears from the Telychian to the Sheinwoodian (Silurian).

The Pterygometopinae may be exclusive to Baltica and are known from the Floian to the Upper Katian with 49 species in 14 genera.

The 71 species from 8 genera belonging to the Eomonorachinae occur mostly in Laurentia from the Floian.

The subfamily spread to Avalonia and Laurentia in the Katian, at the end of which they became extinct.

32 species of Monorachinae in 6 genera occurred on the paleocontinent Siberia, now parts of northeastern Russia and of Alaska, from the Sandbian to the Upper Katian.