Another juicy find is the fossil of a giant wombat the size of a small car.
Although many of the plants and animals that thrived during the Pleistocene are similar to their modern descendents, the period is known for its abundance of giant creatures: woolly mammoth, mastodon, saber-toothed cat, longhorned bison, wooly rhino, and giant ground sloth.
The structure of the Australian cave suggests it worked as a pit trap. The hole leading to the cave was covered with vegetation, said Long, and animals fell in and got trapped.
Entering the cave today requires wriggling through a 10-meter-long (32-foot-long) tunnel that runs from the ground surface to the roof of the cave. Then there is a 15-meter (50-foot) drop to the cave floor.
Death by Starvation
Even with the precipitous drop, Prideaux believes most of the giant animals that fell into the cave didn't die on impact. "It looks like they didn't die for a few days because each specimen was found curled up in a different nook," he said. "They probably walked around and eventually died of starvation and dehydration."
If the animals had died on impact, all the bones would have been found in a heap directly below the hole in the ceiling.
The paleontologists said the site is unique in part because of the distribution of the skeletons in three caves.
Fossil deposits from the Pleistocene era are usually a jumble of sediment-embedded bones from different skeletons, Long explained. Such piles are created as rain or floodwaters gush through the caves, washing the dirt and bones into a corner. Sorting though piles of bones to distinguish various extinct species, some of them perhaps unknown, can be extremely difficult, he said.
"Here the bones are completely undisturbed," said Long. "It is as if the animals just curled up in a corner and never woke up." The cave was probably sealed with dirt because there are no human remains or bones from any modern species.
The bones are in such good condition that Long collected DNA samples from several specimens, which he hopes to use to accurately date the remains. The DNA will also be used to establish evolutionary links to modern marsupials in Australia today.
The Nullarbor Plainsa vast, arid plateau stretching from South to Western Australia and bigger than the state of Texasare riddled with thousands of caves, but very few contain fossils. Even fewer have the dark, dry conditions necessary for preserving remains.
"Thus we have a very poor paleontological record of the flora and fauna from this area, until now," said Long. "This cave is one of the most important megafauna sites in the whole of Australia and offers a snapshot of the diverse collection of animals that existed during the Pleistocene period."
The cave was discovered by Father Ken Boland of St. Francis' Church in Melbourne, an avid caver and pilot who was conducting a survey of landscape features from his ultralight aircraft. Noting details such as soil color changes, holes, depressions, and fissures, he noticed an interesting feature and sent a ground team to explore.
The ground teammembers of the Australian Speleologial Federationentered the cave for an initial investigation, then withdrew without removing any of the fossil remains. The exact location of the cave is being kept a secret to protect it from looting by fossil hunters seeking specimens to sell on the black market.
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