Palaeo Discoveries in Australia

By Geoff Hughes, UNE Discovery

Continuing our theme of palaeontology, let’s look at some recent discoveries made in the field of palaeontology here in Australia. Our country is an important place for finding fossils; the rocks here are some of the oldest in the world, so some of the oldest fossils can be found here, too. Discoveries can range from the relatively recent, like the Ice Age, to long, loooooong before the dinosaurs. Here are four recent finds made by Australian scientists!

Some examples of a few of the cell type found in Birrindudu Basin. (Reidman et al. 2023)

For our first one, we have to travel quite a long way back. Way before the dinosaurs, way before the first fish, even out past the Cambrian Explosion. Discovered by a team working in the Birrindudu Basin (which crosses WA and the NT border), these fossils are tiny, and very, very old. As in, 1.6 billion years old, give or take. At this time, Earth’s atmosphere had no oxygen, and it was spinning faster – each day lasted only 20 hours. This was life’s formative years, and it was quite small. Single cells only, although some of them lived in big clusters. In this particular finding, scientists took rock cores from places known to contain a lot of micro-fossils and broke the rock down with hydrofluoric acid which dissolves the rock but leaves the fossils behind. They found several species of single-celled organisms that were already known, but also four brand new species! The scientists named them Birrindudtuba, Limbunyasphaera, Siphonoseptum, and Filinexum, which are all so fun to try and pronounce.

Some of the fossils of Harajicadectes zhumini. (Choo et al., 2023).

Next, let’s look at something a little more familiar, although it still long predates the dinosaurs: a fish! At another site in the Northern Territory, scientists uncovered several skulls and one mostly full body of a never-before-seen species of fish, which lived in the late Devonian period (372 to 388 million years ago). At this time, Australia was straddling the equator, and was attached to another continent called Gondwana. The oceans were full of fish, but on land, nothing with a backbone lived: only insects, arachnids, and the like. This fish, called Harajicadectes, had strong, fleshy fins, and its enlarged spiracles (nostrils) mean that it probably breathed air, like a lungfish. It is thought to belong to the groups of fish that first crawled onto land (although it would not do so itself).

An artist’s reconstruction of what this dinosaur may have looked like, and where the bone fragment that the scientists found fits into the skull. (Kotevski et al., 2024)

Okay, we’re all here for dinosaurs. Everyone loves a dinosaur! Fortunately, a new predatory dinosaur was recently discovered in Victoria. This was a type of megaraptor, the chief hunting dinosaurs in Australia during the Cretaceous era. Lightning Claw, the big dinosaur skeleton in UNE’s Natural History Museum, was a type of megaraptor. They had really large claws on their hands compared to other types of predatory dinosaur, like Allosaurus or Tyrannosaurus, so it’s thought that megaraptors used these claws to kill, rather than their teeth. This new discovery also shows that they had facial crests; not quite horns, but big crests above the eyes that maybe protected their eyes during fights. The discovery is quite new, and is the first time that a skull fragment has been found from a predatory dinosaur in Australia (besides jawbones).

Finally, let’s look at another dinosaur, but this one lived much closer to us in time. It’s a bird! In modern times Australia doesn’t have very many large birds of prey. Plenty of smaller species of falcon, goshawk, kestrel, etc., but only two really big eagles: the wedge-tailed eagle (Aquila audax) and the white-bellied sea eagle (Haliaeetus leucogaster). It turns out that this wasn’t always the case, and there used to be several other large birds of prey species that lived during the Pleistocene, and some were much larger than a wedgie. Bones from one new species of these giants were discovered in a cave in Naracoorte Caves National Park. The researchers have named it Dynatoaetus pachyosteus, and they estimate that it could have weighed as much as 12 or 13 kg; that’s a big bird! (Mather et al. 2023).

So, that’s what’s been happening in the world of Australian palaeontology. A fine journey through the ages, from the remote and misty past, to an ancient fish, to a new fossil that gives us a clue as to what Australian dinosaurs looked like, and even to a giant eagle that Aboriginal Australians may have seen with their own eyes.

References

Choo, B., T. Holland, A.M. Clement, B. King, T. Challands, G. Young, and J.A. Long. 2023. A new stem-tetrapod fish from the Middle–Late Devonian of central Australia. Journal of Vertebrate Paleontology 43: e2285000.

Kotevski, J., R.J. Duncan, A.H. Pentland, J.P. Rule, P. Vickers-Rich, T.H. Rich, E.M.G. Fitzgerald, A.R. Evans, and S.F. Poropat. 2024. A megaraptorid (Dinosauria: Theropoda) frontal from the upper Strzelecki Group (Lower Cretaceous) of Victoria, Australia. Cretaceous Research 154: e105769.

Mather, E.K., M.S.Y. Lee, D.A. Fusco, J. Hellstrom, and T.H. Worthy. 2023. Pleistocene raptors from cave deposits of South Australia, with a description of a new species of Dynatoaetus (Accipitridae: Aves): morphology, systematics and palaeoecological implications. Alcheringa: An Australian Journal of Palaeontology 48: 134-167.

Reidman, L.A., S.M. Porter, M.A. Lechte, A. dos Santos, and G.P. Halverson. 2023. Early eukaryotic microfossils of the late Palaeoproterozoic Limbunya Group, Birrindudu Basin, northern Australia. Papers in Palaeontology 9: e1538.