The fifth day of the conference and palaeobiogeography takes the centre stage as the main conference theme. We are treated to an incredibly comprehensive survey of the major plant groups of Gondwana by Dr Tania Dutra, complete with stunning visuals. Her main research interest is the Araucaria. She plots out what is known about extant species, the history of the group, migration pathways and even speculation on the future of some Araucarians.

Araucaria is the genus name of the local hoop pines in Australia. They are amongst the tallest trees of the rainforests. Bunya pines, native to the forests north of Brisbane, and very important to the Aboriginals, are also Araucaria. So too are the monkey puzzle trees of South America, and several other species from South America, New Guinea, New Caledonia and Norfolk Island - that is, both sides of the South Pacific. They are related by ancestry of trees in the forests of the great supercontinent of Gondwana: the last major pieces to split apart were South America (which still has Araucaria and marsupials, Antarctica (which used to have both before it froze over) and Australia (which still has both, plus various other plant and animal groups related to those of South America. Because of their size, Araucarians have been an important source of timber, and consequently under threat of extinction in some areas of Brazil.

The Australian Wollemi Pine is also an Araucarian. During the discussions after Dr Dutra’s presentation it was apparent that the story of the discovery of the Wollemi Pine is one that intrigues Gondwana palaeobotanists. The tree, otherwise known as the “dinosaur tree”, was well known from the fossil record and considered to be extinct, before living examples were found in the Wollemi National Park in 1994. There is strong world wide demand for this ancient plant and it’s horticultural development is being undertaken by the Mt Annan Botanical Gardens. It is due for public release some time in 2005.
South American colleagues expressed disbelief that living examples of the Wollemi Pine could remain undiscovered for so long within 150kms of Sydney, a modern city of around 5 million people. Over lunch, I was able to offer some thoughts to help explain this apparent anomaly. It is all a result of the geology of the Sydney region.

Sydney is built on a thick wedge of relatively flat lying Triassic sandstone. As a result of weathering, the sandstone is full of vertical splits called joints that slice down through the layers. The results of this can be quite spectacular forming massive breaks in the rock that can be tracked over long distances in straight lines.

This pattern of extensive vertical joints in sandstone country produces a landscape of steep cliffs and flat lying cliff tops. It has controlled the development of the city of Sydney in subtle ways. The complex dendritic shape of the harbour as a steep sided drowned river valley has made efficient transport systems difficult to design. Despite the proximity to Australia’s largest city, there are still remote and largely inaccessible steep sided sandstone valleys that can nurture such remnant flora. I think my basic geology lesson helped my South American colleagues to understand the Wollemi Pine story.
Other palaeobiological contributions on the day included a presentation from Dr Fabrizo Cecca on theoretical issues related to the determination of individual palaeobiological units. A complex area that during the discussions highlighted a variety of approaches used by different scientists working with different groups of plants and animals. Consensus on determining a universal set of definitions for units seemed some way off in the future.

That night I met an English couple who had just moved to Aracaju. The Atlantic coastline south of the city is for the most part undeveloped and they see great potential in the local real estate and hope to make a large amount of money. While I could not share their enthusiasm for the business opportunities, it was a chance to catch up with the latest results from the Ashes Series. It’s not easy to get any cricket results here! They were pleased to have an Australian to goad about the feats of a resurgent English cricket team.

Someone I met on Atalaia Beach

Parque de Coqueiros, Conference Centre Resort - its a hard life!

Sunset over Atalaia Beach

 

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