Megalania prisca

The Megalania prisca was a giant monitor lizard. It is extinct, and known only from fossil evidence.

The related Komodo Dragon can reach a length of upt to 10 feet (3 meters), but Megalania was at least twice as big, with fossils suggesting up to 23 feet (7 meters). Megalania has been extinct since the ice age.

Mainstream consensus is that there is no reasonable doubt that Megalania is extinct. However, very large monitor lizards, between 20 and 30 feet in length have purportedly been sighted in Australia many times in the last century, and some sightings suggest that it lives also in New Guinea. It has been suggested these sightings are surviving megalania. Most experts would probably regard this conclusion as highly unlikely.