Sthenurus
Sthenurus ("strong tail") is an extinct genus of kangaroos. With a length around 3 m (10 ft), some species were twice as large as modern extant species. Sthenurus was related to the better-known Procoptodon. The subfamily Sthenurinae is believed to have separated from its sister taxon, the Macropodinae (kangaroos and wallabies), halfway through the Miocene, and then its population grew during the Pliocene.[3]
A 1997 study analysed the diets of fauna at various fossil site localities in South Australia, using stable carbon isotope analysis 13C/12C of collagen. It found that at older localities such as Cooper Creek, the species of Sthenurus were adapted to a diet of leaves and twigs (browsing) due to the wet climate of the time between 132 and 108 thousand years ago (kya - by thermoluminescence dating and uranium dating), which allowed for a more varied vegetation cover.
At the Baldina Creek fossil site 30 kya (C14 dating), the genus had transitioned to a diet of grass-grazing. During this time, the area was open grasslands with sparse tree cover as the continent was drier than today, but at Dempsey's Lake (36-25 kya) and Rockey River (19 kya C14 dating), their diet was of both grazing and browsing. This analysis may be because of a wetter climatic period. The overall anatomy of the genus did not alter in response to the change in diet and dentition did not adapt to the varying toughness of the vegetation between grasses, shrubs, and trees.[4]
Other animals found in the Cuddie Springs habitat include the flightless bird Genyornis, the red kangaroo, Diprotodon, humans, and many others.[5][6]
Examination of skeletal remains of Sthenurus from Lake Callabonna, northern South Australia, revealed that as the animals were trapped as they floundered in the clay mud while attempting to cross the floor of the lake during low-water or dry times. The data show that three closely allied sthenurine species coexisted sympatrically at Lake Callabonna: a new giant taxon, S. stirlingi, an intermediate-sized S. tindalei, and the considerably smaller S. andersoni. Comparative osteology of these Sthenurus species with Macropus giganteus emphasizes how different sthenurine kangaroos were from extant kangaroos, especially with the sthenurines' short, deep skulls, long front feet with very reduced lateral digits, and the monodactyl hind feet.[7]
Teapot Creek, a tributary of the MacLaughlin River in the Southern Monaro, southeastern New South Wales, contains a sequence of terraces. The highest and oldest of these terraces was reported to contain the remains of fossil mammals found in Plio-Pleistocene fossil deposits elsewhere in eastern Australia. Sthenurus atlas, S. occidentalis, and S. newtonae are some of the species identified from the fossils found in the terrace.[8]
