Untitled Document
The oldest mother
John Long1,2, Kate Trinajstic3, Gavin Young1, & Tim
Senden4
1 Research School of Earth Sciences, The Australian
National University, Canberra, ACT;
2 Museum Victoria, Melbourne, Victoria;
3 School of Earth & Geographical
Sciences, The University of Western Australia, Perth, WA;
4 Dept. Applied
Maths, Research School of Physical Sciences & Engineering, The Australian
National University, Canberra, ACT.
Figure 1. The oldest known
vertebrate mother, Materpiscis, in the act of live birth - an artistic
reconstruction by RSES Ph.D student Brian Choo .
A well-preserved embryo was discovered inside a 380-million-year
old fossil fish collected from Gogo (Kimberley region, WA), during a
2005research trip under an Australian Research Council Discovery Project
based at ANU (DP0558499; Chief Investigators Gavin Young and John Long).
This has proved to be the oldest example of live birth known amongst
the vertebrates (animals with backbones). The discovery was published
in Nature in May, 2008, and received wide media coverage. The new genus
and species of placoderm (armoured) fish was named Materpiscis attenboroughi
in honour of Sir David Attenborough, who first brought the world-famous
Gogo fossil fish deposit to public attention in the 1979 TV series 'Life
on Earth'.
The Gogo fossil fish are preserved in limestone nodules, and can be
extracted using acetic acid. This specimen was prepared at Museum Victoria
by Dr John Long, Head of Science at the museum, who is also an ANU Adjunct
Professor at RSES. During the acid preparation he discovered a
partly developed small skeleton inside the body cavity of the larger
fish. The specimen was brought to Canberra to be scanned by Dr Tim Senden
(ANU Department of Applied Mathematics) using the 3D XCT scanner built
and housed in the Research School of Physical Sciences & Engineering.
This revealed unique preservation of an umbilical cord and recrystallised
yolk sac, soft tissue structures very rarely observed in fossils, let
alone specimens as old as the Gogo deposit.
Major collections of Gogo fossil fish are held in the
Natural History Museum, London, the WA Museum, Perth, and at the ANU
in Canberra. The ANU collection includes the actual specimens used by
the BBC for the 'Life on Earth' TV production in 1979. Gogo is recognised
internationally as producing the world's best preserved Devonian fossil
fish, complete articulated skeletons that look like modern specimens.
Recent research by John Long and Dr Kate Trinajstic (University of Western
Australia) has shown that phosphatiised muscle and nerve fibres were
also preserved in some specimens (published 2007). In early 2008 Kate
re-examined some placoderm specimens in the WA Museum collection and
found three small skeletons inside another fish (Austroptyctodus) that
is closely related to Materpiscis. The tiny embryos had been previously
overlooked. Earlier research by Dr Gavin Young (RSES) had demonstrated
copulatory organs in male Austroptyctodus specimens, showing that
these placoderms had a very advanced reproductive biology involving 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 to have developed so early in the evolutionary
history of backboned animals.
Another field trip to Gogo in 2008 has yielded a range of new specimens,
including some fish groups not previously found at Gogo. These are currently
being prepared and researched in Melbourne by Dr Long and RSES Ph.D student
Brian Choo. John Long received the Australasian Science Prize for 2008
in recognition of this research, which was also featured as a Case Study
on p. 60 of the Australian Research Council Annual Report for 2007-2008.
Long, J.A., Trinajstic, K., Young, G.C. & Senden, T. 2008. Live birth
in the Devonian Period. Nature 453: 650-652.
Trinajstic, K., Marshall, C., Long, J. & Bifield, K. 2007. Exceptional
preservation of nerve and muscle tissues in Late Devonian placoderm fish
and their evolutionary implications. Biology Letters 3: 197-200 (doi:10.1098/rsbl.2006.0604)