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A well preserved embryo has been discovered inside a fossilised fish some 380-million years old from Gogo, in the Kimberley district of Western Australia. This is the oldest example of live birth known amongst the vertebrates.

Researchers from Museum Victoria, The University of Western Australia (UWA) and the Australian National University (ANU) have collaborated in documenting this remarkable fossil - a new genus and species named Materpiscis attenboroughi , after Sir David Attenborough - in Nature (453, 650-653, 2008).

The Materpiscis fossil was collected during a research trip to Western Australia in 2005 under an Australian Research Council (ARC) Discovery Project based at ANU. Dr John Long, Head of Science at Museum Victoria, extracted the specimen from a limestone nodule by using acetic acid, and discovered a partly developed small skeleton inside the body cavity. The fossil has revealed details of the umbilical cord and recrystallised yolk sac, soft-tissue structures very rarely preserved as fossils. Fragments of the preserved umbilical cord were studied by Dr Kate Trinajstic (School of Earth and Geographical Sciences, UWA) at the CMCA. Further juvenile bones were observed by X-ray microCT (XCT) at ANU by A/Prof. Tim Senden.

Materpiscis belongs to the extinct armoured fish group called the Placodermi . These are common fossils at Gogo, the world's best-preserved site of Devonian fossilised fish. Dr Trinajstic re-examined some key specimens in the museum collection in Perth and found an additional three small embryos inside an adult female of a closely related form, Austroptyctodus.

Previous descriptions of male Austroptyctodus by Dr Gavin Young (Research School of Earth Sciences, ANU) had already indicated an advanced reproductive biology, involving copulation and internal fertilisation, as in modern sharks. The preserved embryos now demonstrate that these placoderms did not lay eggs, but produced live young, a remarkably advanced reproductive strategy for its time. "The Gogo material produces perfect skeletons of ancient skulls and braincases, and recent research has revealed the oldest preserved vertebrate muscle tissue and nerve fibres," said Dr Young. "We hold a very significant Gogo fossil collection at the ANU, the result of many years research - it even includes the specimen used by David Attenborough when he visited Gogo for the 1979 TV series Life on Earth ." A/Prof. Senden added, "We never know, even in well-studied specimens, what additional information may be revealed by new techniques like XCT scanning."

At the press release of the Nature letter, Sir David Attenborough said, "I am very, very flattered, and I am very undeserving. This fish was discovered in a marvellous place, in Gogo, Western Australia - I was very lucky to go there back in the 70s to see this site, where these extraordinary fossils are produced and are preserved in such a wonderful state that you can now look at the details of its anatomy including this fish which actually has a baby in the uterus. It is the first and earliest known vertebrate to have internal fertilisation and to rear its young with a placenta and with an umbilical cord. Now what I've done to deserve that, I really can't imagine."

J.A. Long, K. Trinajstic, G.C. Young and T. Senden, Live birth in the Devonian period, Nature , 453: 650-652, 2008.

Media references

Janine MacDonald (UWA Public Affairs) (+61 8) 6488 5563

Alynka Youngman (Centre for Microscopy, Characterisation and Analysis) (+61 8) 6488 2236