Hylonomus

Hylonomus (hylo- "forest" + nomos "wanderer") was a very early reptile. It lived 312 million years ago during the Late Carboniferous period. As of 2006, it is the earliest confirmed reptile (Westlothiana is older, but may in fact be an amphibian).

Hylonomus was 20 centimeters (8 in) long (including the tail) and probably would have looked rather similar to modern lizards. It had small sharp teeth and likely ate small invertebrates such as millipedes or early insects.

Fossils of Hylonomus have been found in the remains of fossilized club moss stumps in Joggins, Nova Scotia. It is supposed that, after harsh weather, the club mosses would crash down, with the stumps eventually rotting and hollowing out. Small animals such as Hylonomus, seeking shelter, would enter and become trapped, starving to death. Fossils of the basal pelycosaur Archaeothyris and the basal diapsid Petrolacosaurus are also found in the same region of Nova Scotia, although from a higher stratum, dated approximately 6 million years later.

Fossilized footprints found in New Brunswick have been attributed to Hylonomus, at an estimated age of 315 million years.

This animal was discovered by Sir William Dawson in the 1800s. The species name comes from Dawson's teacher, the geologist Sir Charles Lyell.