An arid-adapted middle Pleistocene vertebrate fauna from south-central Australia

Abstract

How well the ecology, zoogeography and evolution of modern biotas is understood depends substantially on knowledge of the Pleistocene. Australia has one of the most distinctive, but least understood, Pleistocene faunas. Records from the western half of the continent are especially rare. Here we report on a diverse and exceptionally well preserved middle Pleistocene vertebrate assemblage from caves beneath the arid, treeless Nullarbor plain of south-central Australia. Many taxa are represented by whole skeletons, which together serve as a template for identifying fragmentary, hitherto indeterminate, remains collected previously from Pleistocene sites across southern Australia. A remarkable eight of the 23 Nullarbor kangaroos are new, including two tree-kangaroos. The diverse herbivore assemblage implies substantially greater floristic diversity than that of the modern shrub steppe, but all other faunal and stable-isotope data indicate that the climate was very similar to today. Because the 21 Nullarbor species that did not survive the Pleistocene were well adapted to dry conditions, climate change (specifically, increased aridity) is unlikely to have been significant in their extinction.

Extinction implications of a chenopod browse diet for a giant Pleistocene kangaroo

“…Landscape burning by humans, who arrived in Australia approximately 50 kyr ago, has been advocated as a more likely explanation than hunting or aridity for the late Pleistocene extinction of Australia's megafauna by means of replacement of nutritious fire-sensitive plants with nutrient-poor, fire-adapted shrub/ grassland mosaics (3,4,27). In the case of P. goliah, however, a major component of its diet (chenopods including a large proportion of Atriplex) was less affected due to its relatively lower flammability (20,24,28,33).…”

“…Recent studies have shown that most species were gone by approximately 45,000 years (kyr) ago (2-3), leaving over-hunting (1,2), landscape burning (3,4) by humans after their arrival approximately 50 kyr ago, and/or increased aridity since the penultimate glacial maximum (6) as the 3 most strongly championed hypotheses. Most arguments are fuelled by the same 3 problems: paucity of well-dated occurrences and knowledge of prehuman faunal change, difficulties distinguishing ''absence of evidence'' from ''evidence of absence,'' and inadequate understanding of the ecologies of extinct taxa.…”

“…W hether climate change, humans, or a combination of factors drove 90% of Australia's large animals (''megafauna'') to extinction during the late Pleistocene has been disputed for well over a century (1)(2)(3)(4)(5)(6). Recent studies have shown that most species were gone by approximately 45,000 years (kyr) ago (2-3), leaving over-hunting (1,2), landscape burning (3,4) by humans after their arrival approximately 50 kyr ago, and/or increased aridity since the penultimate glacial maximum (6) as the 3 most strongly championed hypotheses.…”

Early to middle Pleistocene occurrences of Litoria, Neobatrachus and Pseudophryne (Anura) from the Nullarbor Plain, Australia: first frogs from the “frog-free zone”

“…Precise location data for the site are registered with the Department of Earth and Planetary Sciences, Western Australian Museum, Perth. Fine-grained sediments in unit 3 are of reversed magnetic polarity, which along with overall species composition of the assemblage, indicate an early Pleistocene age (Matuyama Reversed Chron) (Prideaux et al, 2007). This falls within the Naracoortean land mammal age (Megirian et al, 2010).…”

“…High species diversity and remarkably complete preservation are hallmarks of the assemblage, which fills a significant gap in our understanding of the Quaternary biogeography of southern Australia (Prideaux et al, 2007). Leaena 's Breath Cave is the only known Australian vertebrate locality that spans the early to middle Pleistocene boundary.…”