A fossil placoderm fish represents the oldest mother ever discovered

Neither the chicken nor the egg came first. The fossilised remains of the oldest mother ever discovered have been unveiled today. One of the biggest breakthroughs in palaeontology ever made, the specimen is a 375 million year old placoderm fish with embryo and umbilical cord attached, making the fossil the oldest example of vertebrate sex ever discovered.

The finding is one of the most significant ever made by Australian scientists and is published today in the current issue of Nature. The fossil was found in the Gogo area of north-west Western Australia and has been named Materpiscis attenboroughi after the famed naturalist Sir David Attenborough, who first drew attention to the Gogo fish sites in the 1979 series Life on Earth.

The fossil find was made on an Australian Research Council funded expedition led by the paper's lead author Dr John Long of Museum Victoria along with co-authors Dr Kate Trinajstic of the University of Western Australia and Dr Gavin Young and Dr Tim Senden from The Australian National University.

'I think this is one of the most extraordinary fossil finds of all time, as it is the first time in history we have a maternal feeding structure preserved in any fossil. When I first saw the embryo inside the mother fish my jaw dropped, I was silent, stunned like a mullet. I realised that in my hands was the oldest known vertebrate embryo. It dawned on me after studying the specimen that this was the earliest evidence of vertebrates having sex by copulation - not just spawning in water, but sex that was fun! The find was one of several major discoveries we made on the 2005 Gogo Expedition, one of the others was the Gogonasus specimen which featured in Nature in late 2006. We're going back there this year and hope to continue with our strike rate and find something else that will shed light on the early evolution of the first vertebrates. It's one of the main ways we make breakthroughs in palaeontology, to get out in the field and just keep looking,' said Dr John Long, Head, Sciences, Museum Victoria.

'This amazing discovery was made possible by the rare fossilisation of soft tissue, allowing us to see that the embryo was inside its mother and connected by an umbilical cord. This is also the first evidence of sex in vertebrates with jaws. What this tells us is that unlike most other fish that lay eggs in the water, Materpiscis eggs were fertilised internally, the mother provided nourishment to the embryo and gave birth to live young, much like mammals do today,' said Dr Kate Trinajstic, University of Western Australia.

'This is a great example where the classic scientific pursuit of palaeontology meets the space age. This can only happen at a university where we have much greater freedom to follow our research wherever it leads. In tomography we use X-rays to take thousands of flat, 2D radiographs of the specimen at different views, then shoot them off to a super-computer, and get back a 20 Gbyte dataset that represents the specimen in glorious 3D. Next comes the analysis and that's where the work really starts. Micro-tomography give scientists back the dimension they've been missing all these years - space. Micro-tomography is much more than just a 3D microscope - it gives us the chance to simulate lost creatures, new materials and even improve oil recovery. The work at the ANU on developing 3D analysis is leading edge and the focus of a new company to improve oil recovery,' said Associate Professor Tim Senden of the Australian National University.

'To say that I am thrilled by the news puts it mildly. I am extremely flattered that you should give my name to such an astonishing creature. The skill with which you have revealed and identified the umbilical cord is really extraordinary. Thank you for you and your colleagues for this marvellous honour.' said Sir David Attenborough in a letter to Dr Long.

Measuring around 25 cm in length, the mother is an extinct placoderm fish, the dominant group of vertebrates throughout the Middle Palaeozoic Era (c. 420 to 350 million years ago). The placoderms, often referred to as 'the dinosaurs of the seas,' were the rulers of the world's lakes and seas for almost 70 million years.

The fossil will go on display in the foyer of Melbourne Museum from 29 May.