Mad About Science: Mega marsupials

By Brenden Bobby
Reader Columnist

Australia, a.k.a. the Land Down Under, is home to some of the most nightmarish biology to skitter, squirm or swim on the planet Earth. Hey, at least it’s a beautiful continent, right?

Diprotodon vs. man. Who do you think would win in a fight?

It probably won’t surprise you to know that Australia has always swarmed with freaky fauna. Marsupials are pretty strange by mammalian standards, having a weird pouch built into their anatomy to birth and raise their young. Everyone thinks kangaroos are cute and cuddly, until you see one tall enough to play in the NBA at 6.6 feet tall.

Procoptodon goliah was the largest kangaroo ever to exist and died out a scant 15,000 years ago. Unlike today’s kangaroos, P. goliah was incapable of hopping; the Achilles tendon in its leg would have snapped under its weight if it tried. Scientists believe it may have trotted in a similar fashion to humans, which would have been utterly bizarre to watch. The strangest thing about P. goliah must have been its appearance: it had a face that looked like an American Staffordshire Terrier and each foot featured a single clawed toe. While it’s easy to think these creatures evolved into today’s kangaroos, their sole genetic remnant likely exists in wallabies, which weigh around 9 pounds.

The thought of marsupials doesn’t typically incite feelings of terror, but that’s about to change when you learn about Thylacoleo carnifex, a marsupial lion and apex predator of ancient Australia. 

T. carnifex was a strange but brutally effective predator that sported an arsenal of unique evolutionary traits including retractable claws not unlike those of your house cat. Retractable claws are always the sign of a cunning apex predator: protecting these deadly assets while keeping them razor-sharp. But the strangest feature of T. carnifex’s claws was the semi-opposable thumbs on either forepaw — a trait not found in other big cats. These semi-opposable digits allowed the big cat to efficiently climb trees or anchor hold fast to its prey so it couldn’t slip away.

T. carnifex wasn’t the only murderous marsupial lion in the world. Across the Pacific Ocean in South America, Thylacosmilus made its mark as one of the strangest-looking predators in the world. At first glance, Thylacosmilus looked like any other saber-toothed cat — except for a huge bony protrusion from its chin. This protrusion was believed to have housed fleshy pouches in which rested the lion’s teeth, which is odd as it frequently needed to wear down its teeth to keep them from growing too long and becoming unwieldy. Thylacosmilus also had a laughably weak bite for a creature that weighed more than 500 pounds: equivalent to the bite force of a modern house cat. Eventually, Thylacosmilus was driven to extinction as true saber-tooth cats moved into its territory.

Weirdness isn’t measured only by lethality, as the large Palorchestes proves. Palorchestes was a 450-pound marsupial that stood around four feet high and measured more than eight feet in length. It was a stout beast and probably looked a lot like an anteater on steroids. The strangest thing about it, however, was its proboscis. Much like a tapir, Palorchestes’ snout could likely curl and move somewhat independently from the rest of its face. Scientists believe its nose may have been a sort of proto-trunk — a less evolved version of what elephants now have, despite the fact that the two species are completely unrelated to one another.

I’ve saved the biggest and the best for last: Diprotodon was the largest marsupial to ever have walked the Earth, stretching almost 10 feet from nose to tail and weighing more than 6,000 pounds. It likely looked like an oddball combination of a furry rhino, trunkless elephant and a wombat, which makes sense when you take into account that it is an ancestor of today’s wombats. 

Diprotodon lived in herds and were believed to have a social structure very similar to African elephants. The earliest human inhabitants of Australia, who landed there around 50,000 years ago, were believed to have preyed upon the Diprotodon while also worshipping it in a similar fashion to early Europeans and woolly mammoths. As evidence, researchers point to early cave paintings in Australia that depict the giant wombats.

The Diprotodon may also be the inspiration of the bunyip, a mythical creature of Australian lore. While I won’t argue the validity of the existence of the bunyip, I can say for certain that the Diprotodon went extinct about 40,000 years ago.

If you want to trip out your local librarian and see some cool prehistoric megafauna pictures, stop by the information desk at the Sandpoint Library and show them this article. They’ll help you discover all of the weird and wonderful stuff I research on a weekly basis.