Ambulator keanei (van Zoelen J et al 2023; Pliocene; 1m in length) is the second largest wombat next to Diprotodon.

Diprotodon optatum (Owen 1838; Pliocene; 1m in length) is the largest known marsupial of all time. Traditionaly the eight species assigned to Diprotodon nest with wombats and koalas, but here they nest between kangaroos and wombats. The pedes turn inward such that digit 5 is the anteriormost toe.

Pyrotherium sorondoi (Ameghino 1889, 1894, 1895; Billet 2010; Early Oligocene, 29-21 mya; 3m long); data here comes only from its skull, but post-cranial pieces are known indicating a graviportal stance. Wikipedia called Pyrotherium an ungulate and notoungulate close to Notostylops. Other workers (i.e. Shockley et al. 2004) had trouble nesting it. Loomis (1914) thought the naris was between the eyes, as in elephants.

Here Pyrotherium nests between Diprotodon and Pyrotherium among the wombat marsupials (Vombatus). Pyrotherium emphasized the incisor tusks and had four large molars (green) and molar-like premolars (blue). The zygomatic arch and occiput were very high. The nasals are slender bars posterior to the dorsal nares. A short, bulbous trunk probably extended the narial openings anteriorly, just over the mouth.

Propalorchestes novaculacephalus (Murray 1986; Trusler and Sharp 2016; Miocene) is a smaller, earlier and plesiomorphic relative of Palorchestes. So far I've only seen skull data.

Palorchestes azael (Owen 1873; Richards et al. 2019; Miocene to Pliocene; 2m in length) about the size of a horse, Palorchestes had a tapir-like face, likely sporting a similar long proboscis. The lower jaw had a long symphysis, perhaps indicating a protrusible tongue, like an anteater. Large claws tipped the forelimbs. The elbow was unable to bend. Fossils are rare and incomplete.

Ameghino F 1889. Contribución al conocimiento de los mamíferos fósiles de la República Argentina, obra escrita bajo los auspicios de la Academia Nacional de Ciencias de la República Argentina para presentarla a la Exposición Universal de Paris de 1889. Actas Academia de Ciencias. de Córdoba 6:1–1027.

Ameghino F 1894. Sur les oiseaux fossiles de Patagonie; et la faune mammalogique des couches à Pyrotherium. Boletin del Instituto Geographico Argentino 15:501-660.

Ameghino F 1895. Premiére contribution à connaissance de la fauna mammalogique de couches à Pyrotherium. Boletín Instituto Geográfico Argentino 15:603–660.

Billet G. 2010. New observations on the skull of Pyrotherium (Pyrotheria, Mammalia) and new phylogenetic hypotheses on South American Ungulates. Journal of Mammal Evolution. 17:21-59.

Mackness BS 2008. Reconstructing Palorchestes (Marsupialia: Palorchestidae) – from Giant Kangaroo to Marsupial ‘Tapir’. Proceedings of the Linnean Society of New South Wales, 130, 21-36.

Murray PF 1986. Propalorchestes novaculacephalus gen et sp. nov., a new palorchestid (Marsupialia: Palorchestidae) from the mid Miocene Camfield Beds, Northern Territory Australia. The Beagle, Records of the Northern Territory Museum of Arts and
Sciences 3(1): 195–211.

Owen R 1838. Letter in TL Mitchell, Three expeditions into the interior of Eastern Australia. London.

Owen R 1870. On the fossil mammals of Australia. Part III. Diprotodon australis, Owen. Philosophical Transactions of the Royal Society of London. 1870;160:519–578. doi: 10.1098/rstl.1870.0023.

Owen R 1873. On the fossil mammals of Australia. Part IX. Family Macropodidae: Genera Macropus, Pachysaigon, Leptosaigon, Procoptodon, and Palorchestes. Philosophical Transactions of the Royal Society of London 164, 783-803.

Price GJ 2009. Taxonomy and palaeobiology of the largest-ever marsupial, Diprotodon Owen, 1838 (Diprotodontidae, Marsupialia). Zoological Journal of the Linnean Society, 2008, 153, 369–397.

Richards HL, Well RT, Evans AR, Fitzgerald EMG and Adams JW 2019. The extraordinary osteology and functional morphology of the limbs in Palorchestidae, a family of strange extinct marsupial giants. PLoS ONE 14(9): 69 pp.

Trusler P and Sharp AC 2016. Description of new cranial material of Propalorchestes (Marsupialia: Palorchestidae) from the Middle Miocene Camfield Beds, Northern Territory, Australia. Memoirs of Museum Victoria 74:291–324.

van Zoelen J et al 2023. Description of the Pliocene marsupial Ambulator keanei gen. nov. (Marsupialia: Diprotodontidae) from inland Australia and its lLocomotory adaptations. Royal Society Open Science. DOI: 10.1098/rsos.230211 

wiki/Diprotodon
wiki/Palorchestes
wiki/Propalorchestes
wiki/Pyrotherium