A monitor lizard trekking around Mussau in northeastern Papua New Guinea reigns supreme as the remote island's top predator and scavenger. And although it's been around for an estimated million years or more, scientists just recently discovered it.
The paper describes the lizard as "a biogeographical oddity" that has been isolated from closely related species for an estimated one to two million years, according to genetic studies conducted by two study coauthors.
But they have no idea how the lizards, separated by 100 miles or more from their closest relatives, got to Mussau in the first place.
A pregnant female ancestor could have arrived on the island from the islands of New Guinea or New Britain, lead author study author Valter Weijola, a graduate student at the University of Turku, Finland, said in a release. And once that ancestor arrived, it was likely isolated by open seas — which is the same dynamic that's made this area of the Pacific a biodiversity hotspot.
"These islands are full of unique creatures often restricted in distribution to just one island or island group," Weijola said. "Yet, we know relatively little about them. Even large species of reptiles and mammals are regularly being discovered, not to mention amphibians and invertebrates. This is what makes it such a biologically valuable and fascinating region."
These lizards were spotted in the coastal areas of Mussau, but they could also live in the forested inner portions of the island, the authors note.
As for food, they munch on other reptiles, crabs and small birds. Oh, and eggs.
"Usually monitors like these will eat just about anything they can catch and kill, as well as carcass and turtle eggs when available," Weijola said. "While young, Pacific monitor lizards are highly secretive and subsist mainly on insects and other small animals."