Re‐evaluating the evidence for late‐surviving megafauna at Nombe rockshelter in the New Guinea highlands

Abstract

The causes of the Late Pleistocene extinction of most larger-bodied animals on the Australian continent have long been controversial. This is due, in no small part, to inadequate knowledge of exactly when these species were lost from different ecosystems. The Nombe rockshelter in the highlands of Papua New Guinea is one of very few sites on Sahul with as-yet-unrefuted evidence for the survival of megafaunal species until more recently than 40 thousand years (ka) ago. However, our understanding of the age of this site has been based on radiocarbon dating. Here we present new U-Th ages on large marsupial specimens from the deposit and identify a range of postcranial elements to species that include the diprotodontid Hulitherium tomasettii, kangaroo Protemnodon tumbuna and thylacine Thylacinus cynocephalus. Direct U-Th ages of 27-22 ka ago on faunal remains of Protemnodon tumbuna and another large unidentified macropodid are consistent with the existing radiocarbon chronology, yet are minimum ages due to the potential for post-depositional uptake of 238 U and stratigraphic reworking. Pollen analyses indicate perhumid, montane forests dominated by Nothofagus persisted, with minimal human disturbance from at least c.26-20 ka ago up to the terminal Pleistocene. Collagen fingerprinting (ZooMS) demonstrates the potential of protein-based identification of megafaunal remains at Nombe in the future. This study leaves open the possibility of extended coexistence between some megafaunal species in the montane rainforests of New Guinea and intermittently visiting groups of people, and underscores the need for further investigation of the Nombe deposit. Although preliminary, these findings reinforce the view that debates regarding megafaunal extinctions on Sahul require a greater appreciation of species-specific temporalities and the degrees of human impact on diverse habitats across the continent.

Systematics and palaeobiology of kangaroos of the late Cenozoic genus Protemnodon (Marsupialia, Macropodidae)

“…143d) (Hope et al 1993). It does not co-occur with any other species of Protemnodon, but does occur with N. nombe at Nombe Rockshelter (Flannery et al 1983;Prideaux et al 2022).…”

“…Different sites are conflated into a single point in various cases to prevent the map from becoming too cluttered. Oldest and youngest dates provided for each species are in reference to the few dated sites and dated specimens, made with reference to FosSahul 2.0 (Peters et al 2019) and Prideaux (2006). The vast majority of sites yielding material of Protemnodon have not been directly dated, and so we consider it unlikely that these dates represent the full temporal range of the species.…”

“…The range of P. tumbuna reaches across late Pleistocene New Guinea from Nombe Rockshelter in Chimbu Province, eastern central PNG (Prideaux et al 2022) to the West Baliem Valley in montane central Papua Province, West Papua (Fig. 143d) (Hope et al 1993).…”

A review of the late Cenozoic genus Bohra (Diprotodontia: Macropodidae) and the evolution of tree-kangaroos

“…For the others we cannot currently do better than middle or late Pleistocene, which has long been a deficiency that has beset our understanding of change in Quaternary assemblages and extinction trajectories (Prideaux 2006). Bohra paulae, B. illuminata and B. nullarbora may have become extinct in the late Pleistocene at around the same time as numerous other larger species, soon after the arrival of humans in Australia and New Guinea (e.g., Prideaux et al 2009Prideaux et al , 2022Johnson et al 2016;Saltré et al 2016), or they may have disappeared earlier due to climatic changes (e.g., Wroe et al 2013). Faunal turnover at Mt Etna sometime between 280 and 205 ka ago has been interpreted as a response to increased aridity (Hocknull et al 2007), and two frog species bound to free water were lost from the Nullarbor region in the middle Pleistocene (Tyler & Prideaux 2016).…”

Description of the Pliocene marsupial Ambulator keanei gen. nov. (Marsupialia: Diprotodontidae) from inland Australia and its locomotory adaptations

“…The extinct marsupial family Diprotodontidae consisted of large quadrupedal herbivores, with the largest species, Diprotodon optatum Owen, 1838, weighing in excess of two tonnes [ 1 ]. The family inhabited Australia and New Guinea for greater than 26 million years (Ma) until its complete extinction 50–40 ka (thousand years) ago [ 2 – 5 ]. Most systematic studies of diprotodontids have focused on the dentition [ 6 – 14 ], with few describing and comparing cranial or postcranial features [ 15 ].…”