Jeholodens was a primitive mammal belonging to the Triconodonta family, and which lived in present-day China during the Middle Cretaceous about 125 million years ago. Only one specimen has been formally described. This specimen (the holotype) consists of a virtually complete articulated skull and skeleton, it shared its corporal characteristics with most other Mesozoic mammals; it was a long-tailed, nocturnal tetrapod (with prehensile fingers and toes) which hunted insects, its food, during the night.