Pseudopulex is an extinct genus of primitive fleas that lived between the Middle Jurassic and Early Cretaceous periods in what is now modern-day China.

[3] Potential hosts for P. jurassicus include Pedopenna daohugouensis or Epidexipteryx hui, while P. magnus may have parasitized Sinosauropteryx prima or Microraptor gui.

[4] These organisms have similar features to other studied ectoparasites and share traits with present-day fleas, most notably in their wingless bodies and long, sharp stylets that enabled them to pierce through thick skin and hide.

[5] They have several traits that are different from extant crown group fleas which may be an indication of this genus possibly having an early evolution that resulted in a dead-end lineage.

[4] However, between the species of Pseudopulex, there are distinct differences in morphology; P. jurassicus was slightly longer and contained a shorter stylet, while P. magnus was thicker and had very long mouthparts.

[7] They possessed serrated stylets, which were likely used for feeding on blood through thick layers of skin, and are estimated to have been about fifty times larger than the dog flea.