What type of animal did primates descend from?

Primates did not descend from a single "type" of animal, but rather evolved from a common ancestor. This ancestor is believed to have been a small, tree-dwelling mammal, likely similar to a plesiadapiform.

Plesiadapiforms were a group of extinct mammals that lived during the Paleocene epoch (around 66 to 56 million years ago). They possessed some characteristics that resemble early primates, such as grasping hands and feet, but they also had features that are different from modern primates, such as a lack of a postorbital bar (a bony structure behind the eye).

It's important to understand that the evolution of primates is a complex process that involved many branches and lineages. While plesiadapiforms are considered the most likely candidates for the ancestor of primates, there is ongoing research and debate within the scientific community about the exact evolutionary relationships between different groups of early mammals.