Clepsydrops was a primitive amniote from the early Late Carboniferous that was related to Archaeothyris and the synapsids—the ancestors of mammals. Like many other terrestrial early amniotes, it probably had the diet of insects and smaller animals. It probably also laid eggs on land rather than in the water, as most of its ancestors did. A paleobiological inference model for the femur likewise suggests a terrestrial lifestyle for Clepsydrops, as for its more recent relative Ophiacodon, which is consistent with its rather thin, compact cortex. Its jaws were slightly more advanced than those of Paleothyris and Hylonomus.