Australian theropod dinosaurs
The Australian theropod dinosaur fossil record is extremely limited. Triassic and Jurassic theropod fossils are almost unknown. Most Australian theropod fossils come from the Early to mid-Cretaceous, and are often trace fossils such as footprints. Originally, theropods were part of the global fauna, but as Gondwana drifted southwards, the Australian fauna became more distinctively different. Today, the theropods survive as living birds.
The Australian theropod dinosaur fossil record is extremely limited. Triassic and Jurassic theropod fossils are almost unknown. Most Australian theropod fossils come from the Early to mid-Cretaceous, largely because fossil-bearing rocks of this age are exposed at the surface more often than older rocks from the Late Triassic or Jurassic or younger rocks from the Late Cretaceous. There is a single record of a theropod from the Late Cretaceous, an unnamed species from Western Australia known only from a single fragmentary humerus (upper arm bone).
Trackways - the preserved footprints of dinosaurs and other species - can help fill the gaps in the fossil record when body fossils are rare. Theropod footprints from the Late Triassic to Middle Jurassic are known from Queensland, evidence that early theropods were present in Australia shortly after dinosaurs first appeared in the late Middle Triassic. Theropod footprints are also known from the Early to mid-Cretaceous of Queensland. These include the prints of theropod ichnospecies (species based on trace fossils) Skartopus and Tyrannosauropus from the Lark Quarry ‘dinosaur stampede’ site near Winton.
Theropod dinosaurs have had a long history in Australia, from the Late Triassic right up to the end-Cretaceous extinction event. The Triassic Australian theropods must have been part of a global (Pangaean) radiation of early dinosaurs. Later, dinosaurs from the Jurassic of Australia would have been part of a progressively more Gondwanan fauna as the southern continents gradually drifted apart. Australian theropods of the Cretaceous, relatively isolated from most other dinosaur faunas, survived in cool to near-polar climates as Australia remained joined to Antarctica. Today, theropod dinosaurs are still with us as living birds.
Doubtful species and recent discoveries
Many Australian theropods may be nomen dubia (species of doubtful validity). These include Ozraptor subotai, Kakuru kujani, Walgettosuchus woodwardi and Timimus hermani. These species, named on the basis of fragmentary remains, lack diagnostic features that can distinguish them from other theropod species. The recent discovery of Australovenator, the first Australian theropod known from substantial fossil remains, is therefore a highly significant discovery.
Dr Anne Musser , Palaeontologist