These 100,000-year-old footprints were left by a giant wombat, one species of megafauna among many that once roamed Australia. Now artists have created portraits of these lost megafauna for National Geographic, and you can see some below.

In an article accompanying the images, we learn more about how Australian paleontologists got most of their information about the continent's megafauna:

Victoria Fossil Cave, as the cavern is now known, warehouses the bones of something like 45,000 animals. Some of the oldest bones belonged to creatures far larger and more fearsome than any found today in Australia. They were the ancient Australian megafauna-huge animals that roamed the continent during the Pleistocene epoch.

In boneyards across the continent, scientists have found the fossils of a giant snake; a huge flightless bird; a wombat-like creature the size of a rhinoceros; and a seven-foot-tall kangaroo with a strangely short face. They've found the remains of a tapir-like creature; a hippo-like beast; and a lizard, 20 feet long, that ambushed its prey and swallowed everything down to the last feather.

The Australian megafauna dominated their ecosystems-and then were gone in an extinction spasm that swept away nearly every animal that weighed a hundred pounds or more. What, exactly, killed them off?

The answer is complex, but one big issue seems to have been human hunters.

Find out more about Pleistocene Australia in National Geographic. (Thanks, Marilyn Terrell!)

Where once the giant wombat roamed, only footprints remain

Where once the giant wombat roamed, only footprints remain

Giant wombat! According to National Geographic:

The biggest ones reached over six feet tall at the shoulder and ten feet long, their furry, pillar-like legs supporting three tons of weight. Diprotodon occupied a niche similar to the African elephant, browsing on shrubs and collecting at water holes.

Where once the giant wombat roamed, only footprints remain

The deadly marsupial lion was a major predator in Pleistocene Australia.

Where once the giant wombat roamed, only footprints remain

This is a thunderbird with two marsupial tapirs.

Where once the giant wombat roamed, only footprints remain

And of course, the giant kangaroo.