Kan­ga­roo scale

Pro­coptodon go­liah (right), the largest known species of kan­ga­roo, weighed in at about 200kg and would have tow­ered over the largest species to­day, the red kan­ga­roo (be­low). It could reach branches up to 3m from the ground. Stud­ies of fos­sil re­mains have

Australian Geographic - - Geo buzz -

f lesh. Weigh­ing in at 80kg, this would have been a truly fearsome beast. Its op­pos­able thumbs, tipped with enor­mous sheathed claws, sug­gest it was also able to climb trees, and was likely to have been an am­bush preda­tor.

Birds were nu­mer­ous and var­ied, in­clud­ing gi­ant megapodes (the group the mod­ern malleefowl and brush turkey be­long to) and cou­cals (large, ground-based cuck­oos) as well as a host of par­rots, ducks, waders, owls and rap­tor species that still in­habit Aus­tralia to­day. The fact that par­rots nest in tree hol­lows is fur­ther ev­i­dence that the pre­his­toric Nullar­bor was far from tree­less.

Among the trees of this un­fa­mil­iar land­scape you would also have seen many species you may know well, for not all are ex­tinct, and still sur­vive and pros­per to­day. Many have now re­treated from the plain or cling on in rem­nant veg­e­ta­tion around its fringes.

Ex­tant species of pos­sums, bandi­coots, kan­ga­roos and wal­la­bies, wom­bats, bats, lizards and snakes, quolls, devils, bet­tongs, small car­ni­vores such as an­tech­i­nuses and mul­garas, ro­dents such as the de­light­ful and im­pos­si­bly cute hop­ping mice, and birds, were all thriv­ing on the Nullar­bor 500,000 years ago.

This di­verse range of crea­tures with dif­fer­ing habi­tat and di­etary re­quire­ments also points to an equally ex­pan- sive range of f lora, which must have been con­sid­er­ably more var­ied than what can be seen on the plain to­day.

But I have left un­til last the most sur­pris­ing crea­tures found in the caves, that most ac­cu­rately rep­re­sent the enor­mous en­vi­ron­men­tal changes that have oc­curred in the re­gion. After many months of sort­ing through an im­mense pile of small an­i­mal bones, palaeon­tol­o­gists un­cov­ered the re­mains of three frog species, the f irst frogs, liv­ing or fos­sil, to have ever been doc­u­mented on the Nullar­bor. That frogs could live on the plain seems in­con­ceiv­able. One species, the com­mon spade­foot toad

Among the trees of this un­fa­mil­iar land­scape you would also have seen many species you may know well, for not all are ex­tinct.

( Neo­ba­tra­chus sudelli), re­mains wide­spread, and may still turn out to oc­cur there to­day. It is per­fectly adapted to an arid en­vi­ron­ment, and was found in both early and mid-Pleis­tocene sed­i­ments.

Two species dis­cov­ered on the pre­his­toric Nullar­bor – a green tree frog and a toadlet – would have in­hab­ited sea­son­ally moist con­di­tions, and needed tran­sient pools to breed. Th­ese an­i­mals were found in the lower lev­els of the ex­ca­va­tion from the early Pleis­tocene, about 1 mil­lion years and up to 2.5 mil­lion years ago. One of th­ese two species ( Li­to­ria lun­deliusi) was new to sci­ence.

THE NULLAR­BOR TO­DAY is cer­tainly an im­pov­er­ished land­scape. Long gone is the di­verse com­mu­nity of trees, shrubs and grasses. Some­time in the late Pleis­tocene some­thing hap­pened that changed the veg­e­ta­tion for­ever, and along with that change came the loss of the rich di­ver­sity of an­i­mals that de­pended upon it. The Nullar­bor’s Pleis­tocene f lora and fauna evolved to cope with the cli­mate cy­cles that fol­lowed and the slow march to ever-in­creas­ing arid­ity.

Most palaeon­tol­o­gists would agree that it was not cli­mate alone that brought about their demise. Some sus­pect that the hunt­ing of the larger mam­mals by hu­mans after they ar­rived in the area about 50,000 years ago, and per­haps also their use of f ire in the land­scape, was inf lu­en­tial. Al­though not all of the now ex­tinct species sur­vived into the late Pleis­tocene, some cer­tainly did, and ev­i­dence from other sites shows a pe­riod of over­lap with hu­man ar­rival.

The most re­cent bi­o­log­i­cal sur­vey was un­der­taken in 1984 and lists the f lora and fauna known to be ex­tant on the Nullar­bor at Euro­pean coloni­sa­tion 200 years ago. By that time all the large her­bi­vores, apart from the red kan­ga­roo, had al­ready long gone, along with their fearsome car­niv­o­rous preda­tors.

Much of the fos­sil ma­te­rial that has been re­cov­ered from the Nullar­bor so far has yet to be iden­tif ied, and there are other caves that re­main to be ex­plored. It’s likely that many more ghosts may haunt the pas­sages and cham­bers be­neath the end­less land­scape of the Nullar­bor, wan­der­ing for­ever among the trees of an ecosys­tem never to be seen again.

SU­SAN DOUBLE AND AUS­TRALIAN GE­O­GRAPHIC would like to thank Pro­fes­sor Gavin Prideaux for his expert in­put into this ar­ti­cle and Sam Ar­man and Grant Gully for their as­sis­tance with the im­ages.

Spade­foot toad fos­sils have been found in the Nullar­bor’s caves. The species may still be present on the plain to­day, as yet un­seen, be­cause it can re­main buried for many years await­ing rain.

Cavers Eve Tay­lor and Dan Searle pre­pare to ab­seil down through the tiny en­trance into LBC dur­ing an ex­pe­di­tion shortly after its dis­cov­ery.

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