Science Articles

A birth recorded in stone 380 million years ago  

John Long and colleagues at the Museum Victoria in Melbourne, Australia have just published some really exciting findings about one of the fossils they have been studying. We know that many dinosaurs gave birth to live young but it has generally been thought that prehistoric fish reproduced by laying eggs.

The Australian researchers found a fossilised snapshot that proves otherwise – they describe a new species of extinct placoderm fish, and show that its females gave birth to live young. The fossil captures the actual moment of birth. Kate Trinajstic, Research Associate at the University of Western Australia and a co-author of the Nature paper said, "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, Masterpiscis eggs were fertilised internally, the mother provided nourishment to the embryo and gave birth to live young, much like mammals do today."

Ancient fish named after David Attenborough

The ptyctodontid placoderm has been given the name Materpiscis attenboroughi (meaning ‘mother fish Attenborough’). The second part of the name is in honour of Sir David Attenborough, who first brought the world’s attention to the Gogo Formation, where the fossil was discovered, in his Life on Earth series at the end of the 1970s.

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Museum Victoria, Melbourne

Fossil from the Gogo Formation

The fossil was found in an area in northwest Australia which used to be the site of an ancient coral reef. The Gogo Formation, as it is called, has proved rich in fossils from the Devonian period. This mother-fish and her unborn offspring are the latest in a long line of discoveries. Still, it came as something of a moment for celebration for lead author John Long: "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!"

Long went on to say "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. 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."

Long extinct but highly advanced

The placoderm fossil represents the oldest known example of a vertebrate giving birth to live young. It dates from the Late Devonian period, which means its about 380 million years old. Previously, the record for the earliest live birth was held by Jurassic sea reptiles, which lived a mere 180 million years ago.

The fossil is amazingly detailed – the female clearly has a single embryo inside her womb that is connected to her by an umbilical cord. The scientists think that a structure nearby is, or was, a yolk sac. This means that these ancient fish had reproductive biology that was very, very advanced – similar to the reproductive systems found today in modern sharks. The whole biological system of internal fertilisation and giving birth to live young may well have arisen here.

This means that this class of ancient, long-extinct armoured fish could have been a lot more exciting than many scientists had assumed. They would have had sexual intercourse, so may have engaged in elaborate courtship displays. It is also possible that the female fish put a lot of time and energy into caring for her offspring, which was born singly or maybe as twins or triplets. No laying loads of eggs on the sea floor and swimming off into the distance, never giving them a second thought… like many modern fish do.

"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."

Tim Senden ARC Research Fellow at the Australian National University and a co-author of the paper.

Alex Ritchie, Research Fellow in Palaeontology at the Australian Museum, said:

"The Late Devonian Gogo Formation of the Kimberley area, NW Australia, is world-famous for its beautifully preserved fossils of long-extinct fishes that lived and died there 380 million years ago. After 40 years of intensive searching, the Gogo fossil sites still produce surprises, as illustrated by a spectacular discovery reported in this week’s ‘Nature’.  The delicate skeleton of a small armoured fish, painstakingly and skilfully etched by Australian scientists from a limestone nodule, was found to contain a unique and unexpected feature – a single large embryo still connected to the mother by a mineralised umbilical cord. Clearly this baby would have been born alive if the mother had survived. This remarkable fossil provides us with by far the oldest record of live birth in backboned animals and reveals that some early armoured fishes had already developed a very advanced mode of reproduction, not unlike some modern sharks and rays. In a particularly elegant touch the name of the new genus reflects its maternal role and the species name honours the world’s most respected natural history communicator."