Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Hylonomus (pronounced /hä¿l¿n¿m¿s/, hylo- "forest" + nomos "dweller") was a very early reptile. It lived 312 million years ago during the Late Carboniferous period. It is the earliest unquestionable reptile (Westlothiana is older, but may in fact be an amphibian, and Casineria is rather fragmentary). Hylonomus was 20 centimetres (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.