Beaumaris Sandstone : An Invertebrate Palaeontologists Perspective

1. A nippers perspective: wandering along the beach as a child, with an Aunt who insisted that there were trilobites there.

2. Invertebrates yes, but trilobites? No at least not near the

surface. We have heard a lot about vertebrates, and we are excited by these fossils as we have a bias, for we are vertebrates.

a. But if we consider the pyramid of numbers, invertebrates win overwhelmingly.

b. There could perhaps have been other organisms preserved here in abundance, e.g. plants, fungi and protozoans, but their absence is due to the diagenetic processes or what happened to the sediments en route to becoming sandstone.

c. Some of you know that here are fossil plants here however, and I will return to these shortly

3. There are two types of invertebrate fossils preserved here:

a. Whole animal shells (e.g. bryozoans, molluscs, echinoids and barnacles).

b. The traces of animal (and plant) activity (e.g. dominichnia and fodinichnia).

4. The importance of Invertebrata:

a. Charles Darwin, who visited close to here on the Beagle journey, wrote On the origin of Species in 1859. However 5 years prior to this (in 1854), he established his pedigree as a biologist and palaeontologist by studying and writing about barnacles. It was these invertebrates that distilled Darwins ideas about the evolution of life.

b. The barnacle fossils in these sediments are some of the earliest varieties of their forms. Indeed, this is the richest fossil barnacle horizon in Australia. There are species found here that occur nowhere else in the world.

5. Now back to the non-vertebrate fossils:

a. There are numerous examples of fossil tree preserved here. Some of the more observant of you may note that there is Council signage locally explaining that many of the fossils are Banksia remains. They certainly look a bit like

Banksia but this is a falsehood. The only plant fossils I have seen here are the casts of huge logs of Eucalyptus that were carried out into the ancient Proto-Beaumaris Bay after storms. The so-called Banksia are burrows made by mud-shrimps. Some of these knobbly tubes are up to 3 metres long and were up to 50mm in diameter. They were an undersea transport tunnel system for these crustaceans predating Melbournes city loop by about 5 million years. And they are still there! There were millions of them living in the shallow waters of the Bay. These are trace fossils that I mentioned earlier and are complimented by other wonderful burrows and homes of invertebrates that lived here about 5.5 million years ago.

b. Those Eucalyptus tree-trunk fossil casts are special too, because they are often intimately associated with animals that lived off them when they became waterlogged, and rested on the bottom (e.g. wood-worms): They were a valuable food source and a useful substrate for bivalves on an otherwise sandy-silty bottom.

c. There are also some very curious spherical remains interpreted as Bergaueria a very rare trace fossil that was made by sea anemones. These are found in one or two other places in Australia but the other sites are all very ancient. Bergaueria of this nature is unknown elsewhere.

d. Finally, there are the small heart urchins Lovenia, which most fossil collectors in this area are aware of. They are so desirable that one can buy Beaumaris specimens, on-line, from the USA.

6. There are many more observations I could make, but I want to

finish up with a plea This restricted fossil horizon provides a window of past environments and change that is unique to Victoria; it is also unique to Australia; not surprisingly, it is also unique to the World.

7. I want my grandchildren, and their grandchildren, to enjoy this

wonderful site as much as I have. We were caught off-guard when much of the Beaumaris Sandstone was covered with a car park late last century. Development at all cost is not an option here a world heritage listing is!

8. Thank you, ladies, gentlemen and young scientists!