evolution

Stromatolites have been discovered beyond the well-researched south-east corner of Hamelin Pool, in Shark Bay Western Australia, according to a researcher from Bush Heritage.

Stromatolites at Hamelin Pool, WA

Stromatolites at Hamelin Pool, WA

Erica Suosaari donned a wetsuit and spent three years being dragged behind a boat to investigate the entire pool for the first time.

She found stromatolites around almost the entire 135km margin.

“Stromatolites are a big deal,” says Erica.

“They are remnants of the oldest known life form. These structures dominate the fossil record for more than 80 per cent of the Earth’s history. The microbes that built them produced the oxygen that made animal life possible on earth,” she says.

“They represent a huge leap in our understanding of the diversity of modern and ancient life at the site. They effectively offer us a window into early life on Earth.”

Hamelin Pool is a World Heritage Area based partly on the fact that it is home to the largest and most diverse modern assemblage of stromatolites on the planet.

Stromatolites are the remains of living mats of bacteria that trap and bind surrounding sediments or precipitated carbonate cements, leaving behind a rock fabric that causes the structure to grow vertically.

And the bacteria that formed those ancient structures are the reason we’re alive. Their busy photosynthesis for the first few billion years of Earth’s history produced the oxygen that made animal life possible.

They were first discovered in the 1950s but, until now, research on the ancient structures has been concentrated in the south-eastern region of the bay.

Erica was determined to look further and investigated the entire pool for the first time.

She discovered distinct ‘provinces,’ where each has a different and distinct assemblage of stromatolite forms – a result of depth gradient and local environmental pressures.

She estimates there are 100 million stromatolites at the site, including fossils similar to those that existed long before modern times.

Contact: Erica Suosaari, Bush Heritage Australia, 0438 742 011, erica.suosaari@bushheritage.org.au

robinbeck1

A 55-million-year old fossil found in rural Queensland is forcing scientists to rewrite their theories about the origin of Australia’s iconic marsupials, revealing an ancient evolutionary link between Australia and South America.

The fossil, a tiny anklebone smaller than a grain of rice, is from a mouse-sized marsupial previously known only from South America.

“As soon as I saw the bone under the microscope, I knew it was a really significant find,” says Robin Beck, the University of New South Wales paleontologist who carried out the research.

“It has very distinctive features that show it is an ‘ameridelphian’ marsupial, a group that until now was thought to be restricted to South America. It’s a bit like finding a fossil kangaroo in Brazil,” he says.

The bone was collected from the Tingamarra fossil site, near the small town of Murgon in southeastern Queensland. The discovery of a ‘South American’ marsupial shows that 55 million years ago Australia and South America shared at least one group of marsupials in common. At this time, Australia, South America and Antarctica were connected, which may have allowed marsupials to move between the continents.

“This shows that we’re still a long way from fully understanding the history of marsupials in Australia,” Robin says. “I think we can expect plenty more surprises like this in future.”

NSW State Finalist: Robin Beck, University of New South Wales

http://freshscience.org.au/2013/tiny-fossils-link-old-bastard-marsupials-to-south-america-and-africa

Two thymus glands fast-track immune defences

Baby wallaby photos available

Until now, it was a mystery why many marsupials have two thymuses—key organs in the immune system—instead of the one typical of other mammals. Now postdoctoral researcher Dr Emily Wong from the University of Sydney and her colleagues have found that the two organs are identical, which suggests why they are there. [click to continue…]