See the crawling movements of the fetal Australian tammar wallaby through ultrasound imaging, three days before their birth

REBECCA SCOTT: A new international study has shown, for the first time, the movements of the tiny Australian tammar wallaby in its mother's uterus. Using high resolution ultrasound, a team of scientists led by the University of Melbourne and the Leibniz Institute for Zoo and Wildlife Research in Germany, has managed to visualize the developing tammar wallaby three days before birth.

Reproductive biologist, Professor Marilyn Renfree, of the Department of Zoology at the University of Melbourne, and the senior author on the paper, leads the largest research team studying marsupial reproduction and development in the world.

MARILYN RENFREE: These animals really give us an amazing biomedical model. We can use them to understand processes that happen in us because they're mammals. But they separated from mammals like you and I, and sheep, and cows, and monkeys, about 160 million years ago.

So it's like being able to shine a spotlight from a different angle onto the same process. And these comparative studies are really important. And they help us from two points of view. One is for biomedical studies. The other is for conservation of these animals because hardly anyone is studying them. So we have a unique program here at the University of Melbourne studying marsupials.

SCOTT: Ultrasound experts from Germany travel to Melbourne to conduct the examinations in collaboration with the Melbourne University team.

DR. BRANDON MENZIES: International collaboration was very important for this study because our colleagues at the Institute for Zoo and Wildlife Research in Berlin had portable, high resolution ultrasound that allowed us to capture the tiny wallaby from when it was a tiny embryo to right up until birth.

This is really just the tip of the iceberg in terms of studies with marsupials because we've got many, many species that we can now examine. We can look at how they're developing in utero and what other systems that different marsupials use to go from a very small embryo to a fully developed young.

SCOTT: The ultrasound shows the fetus repeatedly thrusting and grasping its forelimbs in a coordinated effort to prepare for its journey from the birth canal to the pouch.

GEOFF SHAW: Wallaby's, when they're born, are extremely small, undeveloped, like an early human fetus. And even though they are born so small and immature, they can climb by themselves from the birth canal up to the pouch and attach with their teeth. And they do it with this lovely Australian crawl movement.

What we found in this study, quite to our surprise, is that that movement starts three days before birth. And they're really very, very poorly developed. The brain is hardly organized, and yet they've got the coordination to organize those crawling movements.

In humans, coordinated movements start about 12 weeks of pregnancy. Wallaby's, the time they saw doing their Australian crawl, about four or five weeks equivalent developmental stage in the human.

SCOTT: The study could provide more insights into human development as well as conservation of the animal species.

MENZIES: The technology has the potential to help, possibly, Australia's endangered species because we can now develop assisted reproductive techniques. Now we know these coordinated movements can occur so early on in brain development it will help us understand how brains develop and maybe it will help us with understanding how premature babies develop.