Lesmesodon ("tooth from Messel") is an extinct genus of placental mammals from extinct clade Proviverrinae within extinct superfamily Hyaenodontoidea (in extinct order Hyaenodonta), that lived during the Early to Middle Eocene. It was found in France and in the Messel Pit in Germany.
Lesmesodon was a weasel-sized mammal.
Lesmesodon has a chewing cycle and pattern of tooth occlusion similar to modern insectivorous predators, and was most likely also an insectivore.
As it grew, Lesmesodon replaced its dP<sub>2</sub> after the eruption of its M<sub>1</sub> and M<sub>2</sub>, which is the ancestral condition in Hyaenodonta.