When megafauna roamed the Margaret River Region

Thylacoleo carnifex was no ordinary marsupial. This fearsome predator, known as the marsupial lion, was a carnivore with a taste for ambush tactics. About the size of a leopard, this carnivorous creature had powerful jaws and retractable claws. Its bite force – believed to be the most powerful of any mammal living or extinct – allowed it to crush bones effortlessly. 

Fossils of Thylacoleo carnifex have been discovered Australia-wide and suggest that the creature was a top predator, providing fascinating insights into prehistoric Australia’s food chain.  

Although built like an apex predator, surprisingly, this fierce hunter is a close relative of the plant-eating koala and the modern wombat.  

The Zygomaturus trilobus, with its large head and prominent cheekbones, was an up to 500 kg plant-eater that once roamed Australia. This wombat-like creature was about the size of a small cow. It belonged to the Diprotodontidae family, which included gigantic, lumbering herbivores and the largest of all marsupials. 

Equipped with sharp incisors, the Zygomaturus was well-adapted for digging into the hard ground to unearth roots and tubers. A preserved jawbone, dated around 44,000 years, is still embedded in flowstone at Mammoth Cave. 

Keep an eye out for ‘Zyggy’ by visual artist Alan Meyburgh perched proudly on the roundabout at the entrance to Margaret River town. 

Take a Western grey kangaroo, add some extra bulk and a heavy koala-like face on a short neck and you’ve got a Simosthenurus occidentalis. 

First discovered in Mammoth Cave, these kangaroos were leaf eaters with muscular hind legs for reaching hard-to-grab branches. Their stereoscopic vision meant they could see the same thing with both eyes but from a slightly different angle.  

Their two robust feet suggest that instead of jumping around, the Simosthenurus’s mode of transport was shuffling. This likely meant they were considered the best dancing megafauna of their time. 

One of the most mysterious of all creatures. The Thylacinus cynocephalus or Tasmanian Tiger survived the mass extinction 46,000 years ago and met the first European settlers in Tasmania – unfortunately, only to face extinction in the 1930s. 

The thylacine could open its jaws to an impressive 120° (that is 30° more than a great white shark) and a tail that was more an extension of its body like a kangaroo and not a dog, meaning it could be used as an additional support to its back legs. 

“Remarkably, scientists discovered Thylacine skeletons at the bottom of the Jewel Cave chambers. 

The giant echidna was first identified from a fossil inside Mammoth Cave in 1909. This spiky individual with its muscular hind legs and strong claws for digging would have weighed 30 kilograms and stood around 1 metre tall. That’s about the size of a sheep, making it the world’s largest monotreme (egg-laying mammal).  

Its long, curved snout and half-a-metre long tongue suggest a diet of grubs, beetles, worms, and other invertebrates – ants alone would not even touch the sides. 

The extinction of megafauna is still a topic of active research, with most discussions focusing on a combination of factors. A slow change in climate likely played a significant role, as Australia’s environment shifted from cold and dry to warm and dry, leading to the loss of surface water and critical food sources for these predominantly browsing animals. Some researchers also explore the potential influence of early human activities, such as hunting and landscape management, as part of a broader set of pressures on megafauna populations. 

The exact causes remain uncertain, and it is widely believed that the extinction was the result of a compounding effect of environmental and ecological changes 

See a Zygomaturus jawbone embedded at Mammoth Cave or hear about the Tasmanian Tiger who fell into Jewel Cave year-round with a self-guided tour. We recommend you book your tour online via the Capes Foundation website to guarantee your preferred tour timeslot. The caves are open 9am – 5pm daily (except Christmas Day). 

The Capes Foundation is a not-for-profit organisation, meaning the money from your ticket will go towards responsible management of the cave attractions to ensure that these precious places are protected, celebrated, and enjoyed for generations to come.

Encounter life-sized megafauna replicas and fossils and learn about their lives inside Mammoth Cave after dark on a Megafauna Nightstalk. Guided by torchlight, continues through the karri forest, revealing the hidden sounds and sights of the forest at night. 

This two-hour adventure runs during July and September school holidays and is recommended for ages seven and up.