Editing Diprotodon (section)

==Research history==
[[File:Evolution in the past (Plate 55) BHL21155651.jpg|thumb|left|Early reconstruction of ''Diprotodon'' by [[Alice B. Woodward]], 1912]]

In 1830, farmer George Ranken found a diverse fossil assemblage while exploring [[Wellington Caves]], [[New South Wales]], Australia.<ref>{{cite book|last=Long|first=G.|year=1967|chapter=Ranken, George (1793–1860)|title=Australian Dictionary of Biography|publisher=Australian National University|url=https://adb.anu.edu.au/biography/ranken-george-2572/text3515}}</ref> This was the first major site of extinct [[Australian megafauna]]. Remains of ''Diprotodon'' were excavated when Ranken later returned as part of a formal expedition that was headed by explorer Major [[Thomas Mitchell (explorer)|Thomas Mitchell]].<ref name="Holden"/>

At the time these massive fossils were discovered, it was generally thought they were remains of rhinos, elephants, hippos, or dugongs. The fossils were not formally described until Mitchell took them in 1837 to his former colleague English naturalist [[Richard Owen]] while in England publishing his journal.<ref name="Holden">{{cite book|last1=Holden |first1=R.|last2=Holden |first2=N.|year=2001|chapter=Bones of contention: monster skeletons and bunyip skulls|title=Bunyips: Australia's folklore of fear|publisher=National Library Australia|isbn=978-0642107329|chapter-url=https://books.google.com/books?id=UnKPCZT0x6kC&pg=PA86}}</ref> In 1838, while studying a piece of a right [[mandible]] with an [[incisor]], Owen compared the tooth to those of wombats and hippos; he wrote to Mitchell designating it as a new genus ''Diprotodon''. Mitchell published the correspondence in his journal.<ref>{{cite book|last=Owen|first=R.|year=1838|editor-last=Mitchell|editor-first=T. L.|title=Three expeditions into the interior of Eastern Australia, with descriptions of the recently explored region of Australia Felix, and of the present colony of New South Wales|publisher=T. and W. Boone|volume=2|pages=362–363|url=http://gutenberg.net.au/ebooks/e00036.html#mitchell2-48}}</ref> Owen formally described ''Diprotodon'' in Volume 2 without mentioning a species; in Volume 1, however, he listed the name ''Diprotodon optatum'', making that the [[type species]].{{sfn|Mahoney|1975|loc=p. 67}} ''Diprotodon'' means "two protruding front teeth" in [[Ancient Greek]]<ref name="Holden"/> and ''optatum'' is [[Latin]] for "desire" or "wish".<ref>{{cite web|url=https://www.latin-english.com/latin/optatum/|title=Details for ''optatum'', ''optati''|website=latin-english.com|accessdate=19 February 2023}}</ref> It was the first-ever Australian fossil mammal to be described.{{efn|Owen, and other naturalists of the time would use ''Diprotodon'', and the other unusual extinct creatures of Wellington Cave and the Australian continent to deconstruct [[progressive creationism|progressive creationist]] arguments. These claimed that God created certain forms to exist in certain environments and time periods, based on the fossils of modern animals such as hyenas – which are today found only in Africa – but were being unearthed in every other continent. This was confounded by ''Diprotodon'' and more of Owen's taxa because they were found nowhere else, and more-typical animals were not found in Australia either, despite the Australian climate's similarity to that of Africa. Owen nonetheless disagreed with [[Charles Darwin]]'s theory of [[natural selection]].{{sfn|Vickers-Rich|1991|loc=p. 8}}}}<ref name="Holden"/> In 1844, Owen replaced the name ''D. optatum'' with "''D. australis''".<ref name=Owen1844>{{cite journal|url=https://www.biodiversitylibrary.org/item/71833#page/282/mode/1up|first=R.|last=Owen|author-link=Richard Owen|year=1844|title=Description of a Fossil Molar Tooth of a ''Mastodon'' discovered by Count Strzlecki in Australia|journal=Annals and Magazine of Natural History|volume=14|issue=91|page=268|doi=10.1080/037454809495170}}</ref> Owen only once used the name ''optatum'' and the acceptance of its apparent replacement "''australis''" has historically varied widely{{sfn|Mahoney|1975|loc=p. 67}} but ''optatum'' is now standard.<ref name=Price2008/>

In 1843, Mitchell was sent more ''Diprotodon'' fossils from the recently settled [[Darling Downs]] and relayed them to Owen. With these, Owen surmised that ''Diprotodon'' was an elephant related to or [[synonym (taxonomy)|synonymous]] with ''[[Mastodon]]'' or ''[[Deinotherium]]'', pointing to the incisors which he interpreted as tusks, the flattening (anteroposterior compression) of the femur similar to the condition in elephants and rhinos, and the raised ridges of the [[molar (tooth)|molar]] characteristic of elephant teeth. Later that year, he formally synonymised ''Diprotodon'' with ''Deinotherium'' as ''Dinotherium Australe'',<ref name=Owen1873>{{cite magazine |url=https://www.biodiversitylibrary.org/page/2326162#page/355/mode/1up|first=R.|last=Owen|author-link=Richard Owen|year=1843|title=Additional evidence proving the Australian ''Pachyderm'' described in a former number of the 'Annals' to be a ''Dinotherium'', with remarks on the nature and affinities of that genus |magazine=The Annals and Magazine of Natural History |volume=11 |issue=71 |pages=329–332}}</ref> which he recanted in 1844 after German naturalist [[Ludwig Leichhardt]] pointed out that the incisors clearly belong to a [[marsupial]].<ref name=Fensham2013>{{cite journal|first1=R. J.|last1=Fensham|first2=G. J.|last2=Price|year=2013|title=Ludwig Leichhardt and the significance of the extinct Australian megafauna|journal=Memoirs of the Queensland Museum|volume=7|issue=2|pages=621–632|url=https://www.researchgate.net/publication/256440954}}</ref> Owen still classified the molars from Wellington as ''Mastodon australis'' and continued to describe ''Diprotodon'' as likely elephantine.<ref name=Owen1844/> In 1847, a nearly complete skull and skeleton was recovered from the Darling Downs, the latter confirming this elephantine characterisation.<ref name=Fensham2013/> The massive skeleton attracted a large audience while on public display in [[Sydney]].{{efn|The specimen was collected by R. B. Turner at [[Kings Creek, Queensland]], and was taken to Sydney in 1847 to be sold at auction. Leichhardt attempted to buy it for the new [[Australian Museum]] but Scottish entrepreneur [[Benjamin Boyd]] outbid him at £50. After being examined by Leichhardt, English geologist Reverend [[William Branwhite Clarke]], and curator [[William Sheridan Wall]], it was shipped to England but the ship was wrecked off the [[Sussex]] coast. Only the skull was saved; it was taken to Owen.<ref name=Fensham2013/>}} Leichhardt believed the animal was aquatic, and in 1844 he said it might still be alive in an undiscovered tropical area nearer the interior. But, as the [[European land exploration of Australia]] progressed, he became certain it was extinct.<ref>{{cite book|year=1976|chapter=Death of the Giants|title=Triumph of the Nomads: History of Ancient Australia|publisher=Springer|pages=51–52|isbn=978-1-349-02423-0}}</ref> Owen later become the foremost authority of Australian palaeontology of his time, mostly working with marsupials.{{sfn|Vickers-Rich|1991|loc=p. 8}}

[[File:Extinct monsters and creatures of other days (6288301841).jpg|thumb|Illustration of a ''Diprotodon'' fossil in the dry lakebed of [[Lake Callabonna]]]]

Huge assemblages of mostly-complete ''Diprotodon'' fossils have been unearthed in dry lakes and riverbeds;<ref name=Price2008/> the largest assemblage came from [[Lake Callabonna]], [[South Australia]].<ref name="Gillespie2008" /> Fossils were first noticed here by an aboriginal stockman working on a sheep property to the east. The owners, the Ragless brothers, notified the [[South Australian Museum]], which hired Australian geologist [[Henry Hurst (geologist)|Henry Hurst]], who reported an enormous wealth of fossil material and was paid £250 in 1893 to excavate the site. Hurst found up to 360 ''Diprotodon'' individuals over a few acres; excavation was restarted in the 1970s and more were uncovered. American palaeontologist [[Richard H. Tedford]] said multiple herds of these animals had at different times become stuck in mud while crossing bodies of water while water levels were low during [[dry season]]s.<ref>{{cite journal|url=https://media.australian.museum/media/dd/Uploads/Documents/36123/ams370_vXVII_11_lowres.4b289a9.pdf?_gl=1*5i3btn*_ga*MjQxOTU0ODIxLjE2NjAyNjIxNTg.*_ga_PZ3L84LQDF*MTY2MzAwNTUzNy4yLjAuMTY2MzAwNTUzNy42MC4wLjA.&_ga=2.52900264.1296749326.1663005538-241954821.1660262158|first=R. H.|last=Tedford|year=1973|title=The diprotodonts of Lake Callabonna|journal=Australian Natural History|volume=17|issue=11|pages=349–354}}</ref>

In addition to ''D. optatum'', several other species were erected in the 19th century, often from single specimens, on the basis of subtle anatomical variations.<ref name=Price2008/> Among the variations was size difference: adult ''Diprotodon'' specimens have two distinct size ranges. In their 1975 review of Australian fossil mammals, Australian palaeontologists J. A. Mahoney and [[William David Lindsay Ride]] did not ascribe this to [[sexual dimorphism]] because males and females of modern wombat and koala species—its closest living relatives—are skeletally indistinguishable,{{efn|Because joeys develop mostly outside the mother's womb, female marsupials do not require the adaptations to the skeleton placentals need to survive gestation and childbirth, equating to few or no skeletal differences between males and females.<ref name=Price2008/> In modern wombats, the female can be slightly but insignificantly larger than the male.<ref>{{cite journal|first1=C. N.|last1=Johnson|first2=D. G.|last2=Crossman|year=1991|title=Sexual dimorphism in the northern hairy-nosed wombat, ''Lasiorhinus krefftii'' (Marsupialia: Vombatidae)|journal=Australian Mammalogy|volume=14|issue=2|pages=145–146|doi=10.1071/AM91019|s2cid=239233162 }}</ref> In koalas, males can be 50% larger than females.<ref>{{cite book|author=Jackson, S.|year=2003|title=Australian Mammals: Biology and Captive Management|publisher=CSIRO Publishing|page=147|isbn=978-0-643-06635-9}}</ref>}} so they assumed the same would have been true for extinct relatives, including ''Diprotodon''.{{sfn|Mahoney|1975|loc=p. 207}}
These other species are:
*''D. annextans'' was erected in 1861 by Irish palaeontologist [[Frederick McCoy]] based on some teeth and a partial mandible found near [[Colac, Victoria]]; the name may be a typo of ''annectens'', which means linking or joining, because he characterised the species as combining traits from ''Diprotodon'' and ''[[Nototherium]]'';{{sfn|Mahoney|1975|loc=pp. 85–86}}
*''D. minor'' was erected in 1862 by [[Thomas Huxley]] based on a partial [[palate]];<ref name=Huxley1862/>{{sfn|Mahoney|1975|loc=p. 104}} in 1991, Australian palaeontologist Peter Murray suggested classifying large specimens as ''D. optatum'' and smaller ones as "''D. minor''";<ref name=Price2008/>
*''D. longiceps'' was erected in 1865 by McCoy as a replacement for "''D. annextans''";{{sfn|Mahoney|1975|loc=p. 101}}
*''D. bennettii'' was erected in 1873 by German naturalist [[Gerard Krefft]] based on a nearly complete mandible collected by naturalists [[George Bennett (naturalist)|George Bennet]] and Georgina King near [[Gowrie, New South Wales]];{{sfn|Mahoney|1975|loc=pp. 88–89}} and
*''D. loderi'' was erected in 1873 by Krefft based on a partial [[palate]] collected by [[Andrew Loder]] near [[Murrurundi]], New South Wales.{{sfn|Mahoney|1975|loc=p. 101}}
In 2008, Australian palaeontologist Gilbert Price opted to recognise only one species ''D. optatum'' based most-notably on a lack of dental differences among these supposed species, and said it was likely ''Diprotodon'' was indeed sexually dimorphic, with the male probably being the larger form.<ref name=Price2008>{{cite journal |last= Price |first= G.J. |year= 2008 |title= Taxonomy and palaeobiology of the largest-ever marsupial, ''Diprotodon'' {{small|Owen, 1838}} (Diprotodontidae, Marsupialia) |journal=Zoological Journal of the Linnean Society |volume=153 |issue=2 |pages=369–397 |doi=10.1111/j.1096-3642.2008.00387.x |doi-access=free}}</ref>