Bulletin

Issue: June 2005

Research in Action

Saharan amphibian the daddy of them all?

La Trobe University specialist in ancient land vertebrates, Dr Ross Damiani, has played a significant role in the discovery of some of the most primitive ancestors of all modern amphibians.

Desert fossil find

Together with North American and French colleagues, the discovery was made while working on fossils discovered in the Sahara Desert in the former French colony of Niger in West Africa.

A paper outlining this and other discoveries from the site by a group including Dr Damiani appeared in the journal Nature in April, 2005.

Dr Damiani, who completed his PhD at La Trobe in 1998 supervised by palaeontologist, Dr Anne Warren, returned here in late 2004 as an honorary visiting research fellow involved in joint research with Dr Warren on Queensland fossil amphibians.

The Sahara amphibian fossils, which date back some 260 million years, were first discovered in 2000 by Dr Christian Sidor of the New York College of Osteopathic Medicine while on an expedition into the desert to search for dinosaur bones with Dr Paul Sereno.

Dr Damiani said many fossils were found in an area which experienced temperatures above 45 degrees C with little or no shelter and frequent sandstorms. Some bone fragments were scattered on the thin layer of sand while others were embedded in rocks protruding through the sand.

Another expedition led by Dr Sidor and financed by the National Geographic Society visited the site in 2003 and returned with additional amphibian and reptile fossils.

Dr Damiani, who at the time was a postdoctoral fellow at the University of Witwatersrand in South Africa, and Dr Sébastien Steyer of the Museum of Natural History in Paris, were allocated the task of analysing the amphibian fossils. Dr Sidor and the rest of the team examined those of the reptiles.

'The new amphibian fossils are among the most primitive amphibians and belong to a group of long-extinct tetrapods - or animals with four limbs, including amphibians, reptiles, birds and mammals - known as temnospondyls.

'Temnospondyls are among the most primitive of all tetrapods, and, more importantly, the type found at this site, known as edopoids, are the most primitive of all temnospondyls. This was a surprise because no fossils of that particular kind had been found outside of Europe or North America before,' Dr Damiani said.

'Furthermore, they were between 40 to 90 million years older than those previously found in the Northern Hemisphere.

'We are not yet sure why these edopoid temnospondyls were at this location but we believe that climate influenced the geographic distribution of tetrapods at this time.

'The important thing about the find is that even at the time they were living in what now is the Sahara, they were living fossils in their own time. This is because they were living some 40 to 90 million years after what was previously considered their time range. The reptile fossils found there are also unusual.'