Chapter 2 - »Nulla Arbor« but Plenty to See
The Nullarbor Plain is in every respect a remarkable place. Not only above but also beneath its surface…
For millions of years sinkholes and blowholes have acted as death traps for countless animals which fell accidentally into the caves or clambered down, attracted by water or fodder, and couldn’t get up again. Today these treacherous holes provide us with a window into the past as their floors are scattered with the fossilised remains of these unfortunate animals. Due to good climatic conditions and the lack of disturbance, a lot of fossils are extremely well preserved and many complete skeletons have been found. The oldest remains so far discovered are about 780,000 years old.
One of the many paleontological treasures unearthed during the last ten years is Procoptodon goliah. This stocky built kangaroo grew over 2 m tall and could reach a maximum weight of up to 200 kg. Procoptodon had a very flat face, long forelimbs and was able to stand on tiptoe propped on its muscular tail to feed on leaves and branches up to 3 m off the ground. Each of its hind feet only had a single toe with a large hoof-like claw. The heavy giant belonged to the Sthenurines, a family of kangaroos that used to be widespread across Australia. Most of its members died out about 50,000 to 30,000 years ago. Procoptodon, however, still bounced happily around when the first Aborigines discovered the Koonalda Cave. Only 15,000 years ago this last member of the prehistoric family also became extinct.
Another giant that once roamed this country and whose bones have been discovered in various places on the Nullarbor is Diprotodon optatum. This charismatic herbivore is probably the best known member of the so called megafauna that dominated life on this continent for more than a million years. The shape of a long-legged wombat but the size of a pony and the weight of a rhinoceros, the Diprotodonis the largest and heaviest marsupial that has ever lived. Its small feet were inturned similar to wombat’s and its head was disproportionately large. Because of its massive size it didn’t have to fear many predators.
The biggest threat came probably in the form of Thylacoleo carnifex, commonly known as the marsupial lion. This cat-like carnivore could measure up to 1.5 m in length and had large serrated incisors designed for biting and ripping flesh. Bones of a Diprotodon found in New South Wales showed clear tooth marks matching those of a Thylacoleo. However, it remains uncertain whether the predator actually killed the Diprotodon or whether it was just scavenging on the carcass. Fossilised remains of Thylacoleo have been found at many sites all over Australia but it was only in 2002 that the first complete skeleton was uncovered, and it was in a cave on the Nullarbor. About 500,000 years earlier a Thylacoleo had wandered across the flat landscape and plunged through the deep entrance hole onto the floor of a cave. It probably didn’t survive the 20 m drop and was instantly killed. When a group of palaeontologists found it half a million years later it was still in prime condition.
But this was not the only surprise the cave had to offer. The cave, which consists of three large chambers, turned out to be a graveyard for members of the megafauna. Among the 69 identified vertebrates were also the bones of some new species including a peculiar looking wallaby with horn-like protrusions over its eyes. The caves which have been named Thylacoleo Caves, are recognised today as one of the most important megafauna sites in Australia. No wonder their location is a well kept state secret.