New material referable to Wakaleo (Marsupialia: Thylacoleonidae) from the Riversleigh World Heritage Area, northwestern Queensland: revising species boundaries and distributions in Oligo/Miocene marsupial lions

Abstract

Gillespie, A.K., Archer, M., Hand, S.J. & Black, K.H., 2014. New material referable to Wakaleo (Marsupialia: Thylacoleonidae) from the Riversleigh World Heritage Area, northwestern Queensland: revising species boundaries and distributions in Oligo/Miocene marsupial lions. Alcheringa 38, 513–527. ISSN 0311–5518.New material of Wakaleo oldfieldi and W. vanderleueri from the Miocene freshwater limestones of the Riversleigh World Heritage Area, northwestern Queensland, is described. This material includes the first known upper dentition of W. oldfieldi and dentaries of both species bearing the previously undescribed and morphologically distinct M3. Previously, the two species were distinguished only by size differences in P3 and the size of P3 relative to M1. Wakaleo oldfieldi exhibits a more plesiomorphic M3 that retains a well-developed talonid basin in contrast to W. vanderleueri, which has lost this structure. The phyletic succession and geological occurrences of Wakaleo species make this genus an important taxon in biochronological analyses of Australian Cenozoic assemblages. At Riversleigh, W. oldfieldi is found in deposits allocated to Faunal Zone B and Faunal Zone C, which are regarded as early and middle Miocene in age, respectively. The presence of this species in the Kutjamarpu Local Fauna of central Australia suggests that fauna may be of a similar age. Broader faunal correlations have suggested Faunal Zone C correlates with the middle Miocene Bullock Creek Local Fauna, which contains the more derived W. vanderleueri. Based on stage-of-evolution arguments, W. oldfieldi should occur in older deposits than those yielding W. vanderleueri. The presence of both species of Wakaleo in Faunal Zone C assemblages at Riversleigh suggests that current presumptions about the contemporaneity of the many Faunal Zone C Sites should be examined more rigorously.Anna K. Gillespie [a.gillespie@unsw.edu.au], Michael Archer [m.archer@unsw.edu.au], Suzanne J. Hand [s.hand@unsw.edu.au] and Karen H. Black [k.black@unsw.edu.au] School of Biological Earth and Environmental Science, UNSW 2052, Sydney, Australia. Received 3.1.2014, revised 21.2.2014, accepted 21.3.2014.