When the upper and lower teeth occlude (fit together), the pseudotalonid acts as a receptacle for cusp Y of the upper molar. Cusp Y is often termed the "pseudoprotocone" in this relationship.
The pseudotalonid serves as a holding area for cusp Y, which is located on the upper molar, when the upper and lower teeth meet (occlude).  Cusp Y is commonly known as the "pseudoprotocone" in this arrangement.