The fossil record of marsupial lions (family Thylacoleonidae) from Australian Oligo Miocene deposits is generally poor. Study of new material of this family collected from Oligo-Miocene limestone sediments of the Riversleigh World Heritage Area, northwestern Queensland adds significant new information about previously described species and also indicates a greater diversity of thylacoleonids during this period of geological time. Two new genera and five new species are described. Reassessment of the holotype of the type species of Priscileo, P. pitikantensis,indicates it shows stronger affinities to species of the genus Wakaleo than it does to Priscileo roskellyae. Priscileo is regarded here to be a junior synonym of Wakaleo. The cranium and lower dentition of Priscileo roskellyae show significant morphological differences from species of Wakaleo, and this species is referred to a new genus, Lekaneleo. Distinctive morphological differences are identified in the M3s of Wakaleo oldfieldi and W. vanderleueri, species previously distinguished only by relative size differences in their dentitions. Functional morphological assessment of postcranial remains of species of Wakaleo suggests that they were probably scansorial or arboreal, but does not support a previous hypothesis of a fossorial habit. Cladistic analyses of the interrelationships of marsupial lions support the referral of Priscileo pitikantensis to the genus Wakaleo. The monotypic genus Microleo is the sister-group to all remaining thylacoleonid taxa. Species of Lekaneleo are the sistergroup to a Wakaleo/Thylacoleo clade. Intraordinal relationships of thylacoleonids were also investigated. Phylogenetic analyses of the interrelationships of Diprotodontia that included representatives of all extinct vombatiform families as well as extant taxa were conducted employing cranial and dental morphological characters. These analyses provide support for the hypothesis that Thylacoleonidae are members of the suborder Vombatiformes. Two species of Wakaleo (W. oldfieldi and W. vanderleueri) present in Riversleigh deposits are also found at other localities - respectively, the Leaf Locality of central Australia (Kutjamarpu LF) and the Small Hills Locality of northern Australia (Bullock Creek LF) - and suggest age estimations of the relevant Riversleigh sites of early Miocene and late Miocene. The phyletic evolution of Wakaleo suggests that some Riversleigh deposits are probably late Oligocene in age.
| Identifer | oai:union.ndltd.org:ADTP/215540 |
| Date | January 2007 |
| Creators | Gillespie, Anna K, School of Biological, Earth & Environmental Sciences, UNSW |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://unsworks.unsw.edu.au/copyright, http://unsworks.unsw.edu.au/copyright |
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