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Paddys Valley, Kimberley Ranges, Western Australia
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Museum Victoria,
Melbourne, Australia
EMu user since 1997
KE client since 1983
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This new fossil specimen at Museum Victoria may link fish and land animals,
rewriting the history of animal evolution. Gogonasus (meaning "snout from
Gogo") was a lobe-finned fish that lived 380 million years ago during the Late
Devonian Period, on what was once a great barrier reef surrounding the
north-west of Australia. Initially described from only a snout by John Long in
1985, this new specimen represents a complete fish and was found by a Museum
Victoria expedition in July 2005 in a limestone nodule in the Kimberley Ranges
known as the Gogo Formation.
Fish fossils preserved there were prepared using weak acetic acid which
dissolves rock without harming the bone material. Four months of delicate
preparation was required for the skull and pectoral fin to be revealed in
perfect 3-D form. This specimen shows us that Gogonasus had large holes,
called spiracles, on top of the head which were used for taking in air. These
structures would eventually evolve into the Eustachian tube or middle ear of
higher land vertebrates. The front fin of Gogonasus shows remarkable
similarity with that of all land vertebrates (tetrapods) in having a
well-developed humerus, ulna and radius. This feature reveals that such fishes
had much more in common with land animals than previously thought. The specimen
was found by Tim Senden of the Australian National University (ANU), who has
developed an ultra-fine CT scanner which was used to study the fossil at a level
of detail never before seen. Research on the significance of the new fossil is a
joint collaboration between Museum Victoria (John Long), the ANU (Gavin Young,
Tim Senden) and Monash University students based at MV (Tim Holland, Erich
Fitzgerald), and was published online in Nature magazine on October 18
2006.
Reproduced courtesy of Museum Victoria
Photographer: John Broomfield
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