Modern rock wallabies appear to outlive by sticking collectively in small areas. Fossils present they should journey

Today, rock wallabies are seen as secretive cliff-dwellers that not often stray removed from the security of their rocky shelters. But the fossil document tells a really completely different story.

New research suggests rock wallabies have been as soon as travellers, shifting throughout nation searching for new habitat. These wandering wallabies, together with one which travelled over 60 kilometres, have been much more cellular than different kangaroos on the time, even their large extinct cousin Protemnodon.

These findings reshape our understanding of how rock wallabies work together with their surroundings and the way they could reply to the more and more fragmented landscapes of contemporary Australia.

Homebodies by nature?

Modern rock wallabies spend their days sheltering in rocky caves, crevices, and boulder piles, rising at nightfall to feed. They have tiny dwelling ranges, typically less than 0.2 square kilometres.

Rock wallabies aren’t fussy eaters, consuming leaves and shoots from grasses or shrubs that develop close to their rocky refuges. This has led to the belief that they don’t journey far, sticking collectively in small teams on remoted habitats. Why journey far when all the things you want is true exterior your shelter?

We noticed the identical sample of their distant cousin, the large forest wallaby, Protemnodon, which had small ranges despite their much larger bodies.

Male rock wallabies have been noticed often dispersing up to 8km between colonies. While such actions are uncommon, they could play a vital function in maintaining gene flow between populations.

Rock wallabies happen in remoted areas throughout a lot of mainland Australia, from the Cape York rock wallaby on the northern tip of Australia, to the yellow-footed rock wallaby of the Flinders Ranges, South Australia, and west to the Rothschild’s rock wallaby within the Pilbara, Western Australia.

This broad distribution raises intriguing questions. Were rock wallabies as soon as extra cellular than they appear as we speak? And if that’s the case, can we see proof of that motion within the fossil document?

Mount Etna caves

North of Rockhampton, Mount Etna Caves National Park sits proper within the coronary heart of rock wallaby nation. Rich fossil deposits present a window into the previous 500,000 years, revealing how kangaroos as soon as lived.

From these deposits, we examined fossils from kangaroos of all sizes, starting from tiny pademelons (Thylogale), by means of to the megafauna forest wallaby (Protemnodon), as giant as an grownup human. This allow us to examine how far different-sized kangaroos travelled. Did small species keep closest to dwelling whereas the biggest roamed?

How fossil enamel reveal childhood location

To reply these questions, we turned to clues hidden in teeth. When kangaroos eat, distinctive chemical signatures (strontium isotopes) turn out to be locked of their enamel.

Because enamel kinds early in life and doesn’t change, the strontium preserved in an animal’s enamel can inform us the place it grew up. At Mount Etna Caves, there isn’t a proof kangaroo stays have been brought there by predators to eat. So, we might be assured the patterns we see of their enamel mirror actual actions through the animal’s lifetime.

Our outcomes confirmed that no matter measurement, most kangaroos have been locals. Rock wallabies confirmed sturdy web site constancy, foraging lower than 1km from the caves the place their fossilised stays have been discovered.

This sturdy attachment to rocky shelter mirrors fashionable species observations. Even because the surroundings modified over lots of of 1000’s of years, most rock wallabies maintained small dwelling ranges.

The travellers

While most rock wallabies saved near the caves, a number of people discovered at Mount Etna Caves have been born elsewhere. Some originated 8km north close to Mount Yaamba, and others round 15km south close to Mount Archer.

But our most stunning case was a really adventurous person that travelled not less than 65km, crossing mountains, floodplains, and even the Fitzroy River, which might have been prime crocodile country. This is the primary direct proof of long-range journey in a person rock wallaby.

While actions over these sorts of distances haven’t been noticed in rock wallabies as we speak, genetic proof from short-eared rock wallabies does present some connection between colonies separated by 67km.

This means that, though most rock wallabies keep native, a small variety of travellers will depart their birthplace searching for new habitat. These uncommon long-distance dispersers would play an necessary function in keeping populations connected across the landscape. Because this type of dispersal occurs past the timeframes of human commentary, with out the fossil document we wouldn’t know this significant a part of rock wallaby pure historical past.

Modern implications

Importantly, our outcomes additionally present fossil wallabies have been dispersing from areas which are nonetheless dwelling to rock wallabies as we speak.

Unadorned rock wallabies nonetheless dwell round Mount Etna and Capricorn Caves, with one other colony within the Mount Archer National Park. To the west of the Fitzroy River, Herbert’s rock wallaby occupies rocky outcrops, simply outside the town of Westwood.

Isotopic proof tells us that, prior to now, these three teams weren’t remoted pockets however a part of bigger interconnected populations.

We don’t know whether or not rock wallabies are nonetheless attempting to make these journeys. But with main roads and improvement now dividing the panorama, people may inadvertently be creating boundaries for these uncommon however essential dispersal occasions.

Fossil and genetic proof exhibits rock wallaby populations shouldn’t be seen as remoted colonies, however as elements of a wider community that depends on long-distance dispersal to remain wholesome. Recognising that is important if we wish these rock-loving, wandering wallabies to maintain thriving in an more and more urbanised surroundings.