Queensland Outback dinosaur Discovery

The Queensland Outback has long been known for its dinosaur treasures but this week brought news of a discovery of a cave of fossils that impressed even the most ardent dinosaur fans.

Scientists from the University of News South Wales have discovered a cave containing a large number of 15-million-year-old fossils of prehistoric marsupials in the Queensland Outback, a discovery that has revealed some surprising similarities between the long lost creatures and modern-day kangaroos and koalas.

The cave has kept the fossils beautifully preserved, and includes 26 skulls from an extinct, wombat-like marsupial called Nimbadon lavarackorum, a creature about the size of a sheep with giant claws. The findings were published in an article this week in the Journal of Vertebrate Paleontology.

University of New South Wales paleontologist Mike Archer, who is a co-author of the article said, "It's extraordinarily exciting for us," It's an extra insight into some of the strangest animals you could possibly imagine."

The dig site is located near Riversleigh in northwest Queensland (about 50km south east of Charlieville) and researchers have been digging at the site since 1990. The Nimbadon Skulls were found in the area in 1993 and were amazed at how well preserved the fossils were and even more so by how many they found.

The number of skulls found clustered together suggests the animals may have traveled in mobs or herds similar to modern-day kangaroos, said paleontologist Karen Black, the research team leader.

How the animals all ended up in the cave is still a mystery. One theory offered is that the mob accidentally fell into the cave through an opening obscured by vegetation and either died from the fall, or became trapped and perished sometime later.

The Nimbadon skulls included those of babies still in their mothers' pouches, which gives the researchers an insight into how the animals developed. The babies skulls revealed that bones at the front of the face developed quite quickly, which would have allowed the baby to suckle from its mother at an extremely young age.

This suggests that the Nimbadon babies developed similarly to how kangaroos develop today, probably being born after a month's gestation and crawling into their mother's pouch for the remainder of their development, Black said.

The Nimbadon also appears to have something in common with another marsupial. The fossils revealed the creatures had large claws, which may have been used to climb trees the way koalas do, Black said.

Paleontologist Liz Reed of Flinders University in South Australia said that the discovery of the fossils is very significant.

"To find a complete specimen like that and so many from an age range is quite unique," said Reed, who was not affiliated with the study. "It allows us to say something about behavior and growth and a whole bunch of things that we wouldn't normally be able to do."