The Devonian Fishes of Canowindra

By Jack Saxon

During 1996 stocks of my little book "The Fossil Fishes of the North of Scotland" could be seen to he very low. I was therefore faced with the alternative of a third reprint or a complete revision leading to a third edition. Among the problems which a revision threw up was that Prof Stewart had recorded the presence at Achanarras Quarry of a single specimen of the agnathan (jawless fish) Jamoytius. Now Jamoytius is a Silurian genus which does not fit comfortably into the Devonian context of Achanarras. I thought that it might be nothing more than a specimen of that problematic agnathan Achanarella. This is usually preserved as little more than a black smudge showing only a shadowy structure in the head end. During 1996 I found my very first specimens of this fossil and I began to have misgivings as to whether it was an agnathan at all. A further problem with Prof. Stewart's specimen was that it was in the Australian Museum in Sydney!

The person in charge of vertebrate palaeontology at the Australian Museum was Dr. Alex Ritchie, an old colleague of mine and, since a family visit down under was in the air, I wrote to him asking if I might see the specimen, giving him the dates of our travel itinerary. In his reply he indicated that he had yet to be convinced that the Jamoytius from Achanarras or Achanarella really were agnathans. He added that, if we could extend our visit to Sydney by several days, he would take us to see the famous Devonian site at Canowindra.

We duly arrived at the Australian Museum and spent several days exploring the material in the vaults; this is always more rewarding than looking at the displays intended for public consumption. The Jamoytius, at first glance, did look superficially like Achanarella but, under the microscope, it revealed quite a lot of structure which was not present in Achanarella. We then got out the material from Lanarkshire; it did not resemble the Silurian Jomoytius in the least. I have learned from practical experience that it is unwise to consider any fossil assembly in isolation since places now remote from each other were not always so; in the early Palaeozoic there appears to have been one super-continent which geologists call Gondwana and the continents as they appear on our modern maps took up their present shapes and positions relatively recently in geological terms. The Gogo Formation in north-western Australia contains genera present in our Orcadian Basin. The Gogo Formation was a marine environment however, and the fossils contained in it are preserved in the round and in nodules. Preparation consists of removing the matrix of the nodule to reveal the white bony structure of the fish. Among these fossils was Holonema which I had previously only known from fragments of bone from the Bressay Flags in Shetland. I also got my first look at the fossil fishes from Canowindra. These, too, are preserved in the round but, instead of white bone, we get complete casts of the external parts of the fishes. Latex moulds can then be made from these and casts can be prepared which show the minute detail of these fishes. This mass extinction appears to have taken place during a drought which shrank the pool and the fishes crowded together in their death throes.

Canowindra is a small town lying some 300 km west of Sydney and the journey involves crossing the Blue Mountains. In the early days of settlement in New South Wales these mountains were considered to be an impenetrable barrier to inland expansion since every canyon ended in near-vertical precipices of considerable height. It was only by scaling the peaks that a way was found through them. Inland of the Blue Mountains there is rolling green countryside which makes excellent farm land.

The fossils were first discovered in 1956 when a bulldozer, working on a dangerous bend on the Gooloogong road, turned over a huge rock about 2m in length and lm in breadth. It contained over 100 mainly complete Devonian fishes. The original site was lost when the road was finally made up. In the 1980s Alex Ritchie tried to rediscover the site using a few hand-tools. It was quickly apparent that rather heavier gear was needed and, with local help and the loan of a 20 tonne digger, the site was re-discovered, even though this meant removing part of the road itself and remaking it once the fossils below had been removed. The site is now clearly sign-posted..-

"THE AGE OF FISHES - THE ORIGINAL FISH FOSSIL SITE."

The people of Canowindra have become very enthusiastic about this remarkable fossil find on their doorstep; they have even created an ice cream confection which they call Canowindra grossi after one of the fossil fishes. The elegant little Court-house has become the first museum housing a lecture theatre and a tank containing living lung-fish, which have remained almost unaltered since the Devonian period. The railway goods yard and shed have become the temporary home of the 200 tonnes of fossils from the site and there are plans to build a visitor centre where the material will be put on display. Funding is coming in from many sources, amongst which is the offer of a two-day dig under the supervision of Palaeontologists. These digs include transport to and from the site, accommodation, lectures, meals and hands-on collection and preparation at a cost of about �300.

The genera found at Canowindra consist of the armoured fishes Remigolepis, Bothriolepis, Groeniandaspis and the crossopterygian Canowindra grossi. There is also a very large crossopterygian which has not yet been described and which is almost 2m in length.

I cannot help but wish that some of the enthusiasm shown at Canowindra could rub off for our own native Caithness fossils. We have more genera than at Canowindra and, goodness knows, the economy could do with a shot in the arm. What about an age of fishes museum in Caithness? What about two-day digs to add to the museum collection? What about involving the universities and national museums and what about looking for funding for such a project?