Editing Diprotodon (section)

===Migration and sociality===
[[File:Condamine River ChinchillaQLD 2012mar.JPG|thumb|left|One ''Diprotodon'' herd was making seasonal migrations along the [[Condamine River]] (above).<ref name="Price2017"/>]]

In 2017,  by measuring the [[Isotopes of strontium|strontium isotope]] ratio (<sup>87</sup>Sr/<sup>86</sup>Sr) at various points along the ''Diprotodon'' incisor QMF3452 from the Darling Downs, and matching those ratios to the ratios of sites across that region, Price and colleagues determined ''Diprotodon'' made seasonal migrations, probably in search of food or watering holes. This individual appears to have been following the [[Condamine River]] and, while apparently keeping to the Darling Downs during the three years this tooth had been growing, it would have been annually making a {{cvt|200|km}} northwest-southeast round trip. This trek parallels the [[List of mammals that perform mass migrations|mammalian mass migrations]] of modern-day East Africa.<ref name="Price2017">{{cite journal|last1= Price|first1=G.J.|last2= Ferguson|first2=K.J.|last3=Webb|first3=G.E.|last4= Feng|first4= Y.|last5= Higgins |first5= P.|last6= Nguyen |first6=A.D. |last7= Zhao|first7= J.|last8= Joannes-Boyau |first8= R. |last9= Louys |first9= J. |display-authors=6 |year= 2017 |title= Seasonal migration of marsupial megafauna in Pleistocene Sahul (Australia–New Guinea) |journal= Proceedings of the Royal Society B: Biological Sciences |volume= 284 |issue= 1863 |page= 20170785 |doi= 10.1098/rspb.2017.0785 |pmid=28954903 |pmc= 5627191}}</ref>

''Diprotodon'' is the only identified [[metatherian]]{{efn|Metatheria includes marsupials and all [[theria]]n mammals more closely related to marsupials than placentals.}} that seasonally migrated between two places. A few modern marsupials, such as the red kangaroo, have been documented making migrations when necessary but it is not a seasonal occurrence. Because ''Diprotodon'' could do it, it is likely other Pleistocene Australian megafauna also had seasonal migrations.<ref name="Price2017"/>

''Diprotodon'' apparently moved in large herds. Possible fossilised herds, which are most-commonly unearthed in south-eastern Australia, seem to be mostly or entirely female, and sometimes travelled with juveniles. Such [[Sexual segregation (biology)|sexual segregation]] is normally seen in [[polygyny in animals|polygynous]] species; it is a common social organisation among modern megaherbivores involving an entirely female herd save for their young and the dominant male, with which the herd exclusinvely breeds.<ref name=Price2008/> Similarly, the skull is adapted to handling much-higher stresses than that which resulted from bite alone so ''Diprotodon'' may have subjected its teeth or jaws to more-strenuous activities than chewing, such as fighting other ''Diprotodon'' for mates or fending off predators, using the incisors.<ref name=Sharpe2016/> Like modern red and grey kangaroos, which also sexually segregate, [[bachelor herd]]s of ''Diprotodon'' seem to have been less tolerant to drought conditions than female herds due to their larger size and nutritional requirements.<ref name=Price2008/>