Silhouettes
Artists use fossil assemblages to recreate images of lost worlds, allowing us to visualise the earth as it might once have been. Done well, these drawings can look ‘complete’, as if we know everything about those ancient times. As helpful as this is, it can also be deceptive because fossil assemblages are always fragmentary – a few measly pieces from a much, much bigger jigsaw. We don’t even know what all the missing pieces are … but sometimes we can take a guess. Hidden on many pages in this book are silhouettes, grey shapes that represent animals that are known from fossils to have existed in similar environments, at a similar time elsewhere in Australia. They may well have lived in Tasmania, too, and we haven’t found them … yet.
There is always something more to find!
There is always something more to find!
The Permian Predator Fish
Fish lived in the Permian ocean but their fossil record is surprisingly sparse. In Tasmania it is currently limited to a few scales and bones at a single site in the north-east of the state. We know there were fish in the sea; we also know that some of those fish would have been larger predators. Fossil evidence of large, predator fish are known from Permian rocks in Western Australia. Where is our Tasmanian predator? Perhaps we need to keep looking!
The Triassic Dragonfly
The presence of insects in the Tasmanian Triassic swamp has been confirmed by a small number of fossilised wing impressions. The relative rareness of insect fossils may be due more to the fragile nature of their remains and the difficulties of preservation than it is to a lack of species. Elsewhere in Australia, Triassic swamps in the Sydney Basin were home to some extraordinary insect life. Fossils from the Hawkesbury Sandstone in New South Wales preserve the remains of Clatrotitan, a distant ancestor of modern dragonflies. With a wingspan between 30 – 40cm wide, Clatrotitan would have been astonishing to our eyes. Did the Tasmanian Triassic swamp hum with the sound of enormous insect wings? Perhaps we need to keep looking!
The Jurassic Dinosaurs
The Jurassic period is famous as part of the age of dinosaurs, when giant reptiles dominated both land and sea. Dinosaurs are known to have lived in Gondwanaland during this time. Bones and bone-fragments of two-legged predator therapods are found in Western Australia and Antarctica. Finds in Queensland and Antarctica indicate that large four-legged herbivorous sauropods were also around during this time. In Tasmania, with relatively few Jurassic-age sedimentary rocks perhaps it is not a surprise that we don’t yet have any Jurassic dinosaur fossils. Was that lush forest really free of giants? Perhaps we need to keep looking!
The Cretaceous Pterosaurs
Although not classified as dinosaurs, Pterosaurs are well-known as flying reptiles that existed from the mid-Triassic to the end of the Cretaceous. In Australia, several types of pterosaur including Mythunga, Aussiedraco and Ferrodraco have been described from Cretaceous-aged fossils unearthed in Western Queensland. In southern Australia a number of small bones, suspected to be Pterosaurs were uncovered at Dinosaur Cove in the 1980s. More recent studies have now confirmed this to be correct but the bones available are too few to fully picture the animal itself. What did southern Australia’s flying reptiles really look like? Perhaps we need to keep looking!
The Tertiary Mammals
Mammal fossils found in Cretaceous-age rocks indicate that a range of different species and types already existed during this time period. It is speculated that the small size of Cretaceous mammals, their life habits and diet may all have played a role in assisting them to survive the extinction crisis at the end of that period. But, what then? The mammal record into the Tertiary era is remarkably small until around 20 – 25 million years ago. At this point we find a number of fossil assemblages all around Australia – including at Wynyard and Geilston Bay in Tasmania – which again point to a rich and varied fauna. So what happened during all those years in between? How do our modern mammals relate to their Cretaceous ancestors? We definitely need to keep looking!
The Tertiary Turtle
A single, small fossil found at Taroona, just south of Hobart, in the late 1960’s preserves the remains of a Chelid, a freshwater turtle. Estimated as between 5 – 30 million years old, this little creature is intriguing as it looks like Chelid turtles that are still found in mainland Australian rivers but not in Tasmanian ones. There are no freshwater turtles in Tasmania today meaning that sometime in the past these animals became locally extinct. When did they die out? Why? To answer those questions, we need to keep looking!
