It wasn’t all koala-spotting on our trip across the ditch (the Tasman Sea, for those readers not familiar with New Zild as it is spoken, lol). Apart from the glories of Melbourne (lovely old buildings, the stunning King Tut exhibition in Melbourne Museum, floral Doc Marten boots mmmmmm – & of course the restaurants of Lygon Street!), we also spent time on the Great Ocean Road & with friends in Ballarat.
Now, our friends know how much the husband likes fossils, & so for our visit they’d scoped out a few sites that weren’t too far afield, & last Sunday we drove out to Castlemain, picked up a friend of the friends, & headed out to see what could be found. We were sort of expecting a canyon or something, so were slightly surprised to end up out in the bush, not far from a road. It turned out that the road had been driven through some ancient rocks, around 450 million years old, & there were rich pickings in the roadside spoil heaps.
Before long the sound of rock hammers striking slate or chisel was ringing through the air (fortunately unaccompanied by curses as all thumbs remained unscathed). And the husband was absolutely rapt to find that slate after slate, as the rocks were split, contained fossils of graptolites. In the rocks the happy fossickers were splitting, the remains of these strange little animals looked rather like little saw blades, or maybe fern fronds. (There are some nice photos here on the Museum Victoria site – we haven’t yet set things up for some decent shots of our own.)
However, graptolites were actually animals. Each tiny creature lived in a cup-like structure (which, preserved, formed one ‘tooth’ on the saw), and they were interconnected, forming a colony in which the individuals were joined by something akin to a nerve cord. Graptolites diversified in the ancient Ordovician oceans (before dwindling & finally going extinct in the Carboniferous), & may have floated there supported by tiny gas-filled bladders. Strange creatures indeed! However, in phylogenetic terms they were hemichordates, which means that they are placed in a lineage that also includes acorn worms, Amphioxus (Branchiostoma) – and us.
Not every slate contained a fossil, of course. And some concealed other, quite different and very much alive animals:
I will admit that I was glad it wasn’t me who turned over that particular rock (even though this rather handsome beast was only about 10cm long)!