By Astrid Bina and Jia Xin Quek – 3 February 2020
Marsupials are an infraclass of mammals commonly found in Australasia. Any Aussie could easily name its members: kangaroos, koalas, wallabies – that’s just a few of the many we know! However, the classifications of this infraclass may not be common knowledge. In today’s post, we will look at two orders of Australian marsupials and their characteristics in dentition. After all, learning about how marsupials are classified can provide more insight on their anatomy and diet.
Australasian marsupials (Australidelphian) are categorised into two orders: Diprotodontia and Polyprotodontia. This is determined by the different dentitions that distinguish these two orders, which also relate to differences in diet.
Diprotodontia is the largest and most diverse order of marsupials (Duszynski 2016), which includes the most popular marsupials: kangaroos and koalas. The word ‘diprotodontia’ [Di (two) – proto (first) – dontia (teeth)] means two front teeth – all members of this order have a single pair of large incisors in the upper and lower jaw. These grinding incisors make it easy for Diprotodonts to munch on plants and grasses, making almost all of them herbivorous. Considering that they do not eat meat, these marsupials also lack canines.
Meanwhile, Polyprotodontia is the smaller order, consisting of mostly carnivores, omnivores and insectivores. Unlike diprotodonts, polyprotodonts have multiple front teeth, ranging from four to five pairs of upper incisors and two or three pairs of lower incisors. Some also have well-developed canines, ideal for its carnivorous members like the Tasmanian devil. Other well-known polyprotodonts are bandicoots and bilbies.
Using the previous CT scans of marsupial specimens, we generated 3D models of kangaroos, bandicoots and koalas which can be accessed via the University of Sydney’s 3D gallery: https://sydney.pedestal3d.com/grid. Click on the link and take a look at these 3D models and observe the dentition of the various marsupials. Perhaps you can challenge yourself and guess what these animals eat based on their dentition!
Personally, we have really immersed ourselves with new knowledge just from these models alone. We could effectively compare and contrast the skull models, and easily identify the differences in dentition, without having to see the original specimen. We hope that everyone else enjoys the models as much as we have, and also pick one or two new things along the way! Or maybe even spark some interest for future zoologists 😉
Duszynski, DW 2016, The Biology and Identification of the Coccidia (Apicomplexa) of Marsupials of the World, Academic Press, New Mexico, USA, viewed 23 January 2020, https://www.sciencedirect.com/book/9780128027097/the-biology-and-identification-of-the-coccidia-apicomplexa-of-marsupials-of-the-world#book-info
Monroe, MH n.d., ‘Anatomy based relationships – teeth’, Australia: The Land Where Time Began, web log post, viewed 31 January 2020, https://austhrutime.com/marsupials_anatomy_based_relatioships_teeth.htm
Myers, P 2001, ‘Diprotodontia’, Animal Diversity Web, viewed 23 January 2020, https://animaldiversity.org/accounts/Diprotodontia/