Australian Megafauna A-Z: A is for Alkwertatherium
This blog has been going for just over four months now and a couple of weeks ago I broke through the 2,000 hits barrier. Whilst that may be a drop in the ocean for some of the more popular blogs on the internet, the fact that my inane ramblings about palaeontology have been viewed over 2,000 times feels pretty cool and definitely spurs me on to keep writing the blog. So if you’re someone who’s been here before, thank you, I hope you’ve enjoyed my articles and will continue to do. If this is your first time here, welcome!
Now that there are least a trickle of people who read the blog on a semi-regular basis, I wanted to start the first regular feature on Blogozoic. Since I’m a palaeontologist (in training) working in Australia I thought that I should write a series of posts showing off some of Australia’s extinct beasties. So this is the first post in the Australian Megafauna A – Z. Every now and again there will be a new post covering an extinct megafauna taxon whose name begins with a different letter. I do also have an ulterior motive for doing this as it means I will become more familiar with the Australian megafauna whilst I write the series; having not grown up in Australia (I’m originally from Belfast, Northern Ireland and have lived in Melbourne for the past six years), I’m not as clued up on this group of animals as I would like to be.
Before I introduce the first species of the series, I’ll quickly define what I mean when I say Australian megafauna. They were a of group large animal species that existed in Australia until sometime in the Pleistocene. They weighed at least 30 kg, with the largest taxa weighing up to an estimated 2,000 kg! What exactly caused the Australian megafauna to go extinct is still the subject of very intense debate here in Australia, with research continually providing new perspectives on the matter (e.g. a PLOS One paper that came out last week showed via isotope analysis of kangaroo and diprotodontid teeth that southeastern Queensland in the late Miocene and Pliocene was less arid than previously thought, with tropical forests, wetlands and grasslands all present (Montanari et al 2013)). The Australian megafauna were comprised mostly of marsupials, but also contained reptiles and birds, some of which we’ll meet in subsequent posts. Let’s meet the first species in this series then shall we? The first taxon under the spotlight is Alkwertatherium webbi.
Alkwertathrium webbi is a zygomaturine diprotodontid known only from the Alcoota Local Fauna in Northern Territory. The diprotodontids were medium to large sized herbivorous marsupials that included the largest known marsupial, the rhino sized Diprotodon opatum (you may hear about it in a few posts time). There are two currently recognised sub-families of diprotodontids, the Diprotodontinae and the Zygomaturinae, of which A. webbi belongs to the latter. The two sub-families are distinguished mainly on the basis of differences in the structure of their third premolar.
Alkwertatherium webbi was a small zygomaturine, around the size of a horse. The holotype specimen, found at the famous fossil bearing site at Alcoota Station, includes a skull with lower jaws and measured just over 40 cm in length. The features of Alkwertatherium’s skull show similarities to several other zygomaturine taxa, causing confusion to those who have attempted to decipher its phylogenetic position. Some workers (Black and Archer, 1997) have placed it within the Zygomaturinae, whereas Murray (1990), in the paper where he described the holotype specimen, suggested it was in fact the sister taxa to all other zygomaturines, a claim that would mean it was the sole survivor of this ancestral group due to its Late Miocene age. Mackness (2010) follows the placement of Black and Archer (1997), in addition to stating that the archaic features of Alkwertatherium support the view that the Zygomaturinae evolved from basal Diprotodontinae.
Despite not being as well-known as other extinct megafauna taxa, Alkwertatherium gives a glimpse into past diversity in Australia. That’s the first in the Australian Megafauna A – Z Series; stay tuned for more to come in the following months!
Black, K and Archer, M (1997) Silvabestius gen. nov., a primitive zygomaturine (Marsupialia, Diprotodontidae) from Riversleigh, northwestern Queensland. Memoirs of the Queensland Museum 41: 193-208.
Mackness, B (2010) On the identity of Euowenia robusta De Vis, 1891 with a description of a new zygomaturine genus. Alcheringa 34:455-469.
Montanari S, Louys J, Price GJ (2013) Pliocene Paleoenvironments of Southeastern Queensland, Australia Inferred from Stable Isotopes of Marsupial Tooth Enamel. PLoS ONE 8(6): e66221. doi:10.1371/journal.pone.0066221
Murray, PF (1990) Alkwertatherium webbi, a new zygomaturine genus and species from the late Miocene Alcoota Fauna, Northern Territory (Marsupialia, Diprotodontidae). The Beagle, Records of the Northern Territory Museum of Arts and Sciences 7: 53-80.