DIVERSITY AND SYSTEMATICS OF MARSUPIAL LIONS FROM THE RIVERSLEIGH WORLD HERITAGE AREA AND THE EVOLUTION OF THE THYLACOLEONIDAE ANNA K GILLESPIE Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy in the School of Biological, Earth and Environmental Sciences, University of New South Wales 2007 i ABSTRACT 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 sister- group 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. ii 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. iii TABLE OF CONTENTS Abstract i Table of contents iii List of figures vii List of tables ix Acknowledgements x Publications xii Chapter 1. Introduction 1 Chapter 2. Materials and Methods 3 Chapter 3. Thylacoleonid Diversity 10 Chapter 4. Re-assessment of Priscileo pitikantensis Rauscher 1987 and the identification of a plesiomorphic species of Wakaleo from Riversleigh 18 4.1 Introduction 18 4.2 Re-assessment of Priscileo pitikantensis Rauscher, 1987 19 4.3 Systematics 22 4.4 Specific attribution of a plesiomorphic Wakaleo species from Riversleigh 24 4.5 Wakaleo hilmeri sp. nov. 28 Chapter 5. Postcranial bones of Wakaleo hilmeri 77 5.1 Introduction 77 5.2.0 Description and Comparisons 81 5.2.1 Vertebral column 81 5.2.2 Cervical vertebra 81 5.2.3 Lumbar vertebrae 82 5.2.4 Sacrum 86 5.3.0 Pelvic girdle 90 5.3.1 Ilia 90 5.4.0 Forelimb 91 5.4.1 Humerus 91 5.4.2 Radius 97 5.4.3 Ulna 102 5.5.0 Manus 103 5.5.1 Hamatum 103 5.5.2 Trapezium 107 5.5.3 Metacarpal I 109 5.5.4 Pollex 111 5.5.5 Digits 111 5.6.0 Pes 115 iv 5.6.1 Calcaneum 115 5.7 Amended description of the scapula of Wakaleo pitikantensis 116 Chapter 6. Wakaleo sp. cf. W. hilmeri 119 6.1 Introduction 119 6.2 Wakaleo sp. cf. W. hilmeri 119 Chapter 7. New material of Wakaleo oldfieldi and W. vanderleueri 128 7.1 Introduction 128 7.2 New material of W. oldfieldi 128 7.3 New material of W. vanderleueri 143 Chapter 8. Lekaneleo roskellyae new combination 152 8.1 Introduction 152 8.2 Systematics 153 8.3 Description of skull, maxillae and dentary 157 Chapter 9. Lekaneleo deminutivus sp. nov. 200 9.1 Introduction 200 9.2 Systematics 200 Chapter 10. Microleo attenboroughi gen. et sp. nov. 207 10.1 Introduction 207 10.2 Systematics 207 Chapter 11. Thylacoleonid intrafamilial relationships 219 11.1 Historical background 219 11.2 Aims 222 11.3 Methods 223 11.3.1 Ingroup and outgroup taxa 223 11.3.2 Character selection and description 224 11.3.3 Parsimony analyses 243 11.4 Results 245 11.5 Discussion 251 Chapter 12. Thylacoleonid interfamilial relationships 258 12.1 Use of names 258 12.2 Historical background 258 12.3 Methods 264 12.3.1 Ingroup and outgroup taxa 264 12.3.2 Character selection and description 265 12.3.3 Parsimony analyses 284 12.4 Results 284 12.5 Discussion 286 Chapter 13. Functional assessment of the postcrania of W. hilmeri sp. nov. and W. pitikantensis 296 13.1 Introduction 296 v 13.2 Methods and materials 299 13.3 Results and discussion 305 Chapter 14. Biostratigraphy, Biochronology and Palaeoecology of Riversleigh thylacoleonids 334 14.1 Introduction 334 14.2 Riversleigh geology 334 14.3 Riversleigh Biostratigraphy and Biocorrelation 338 14.4 Intracontinental correlations 342 14.5 Diversity and palaeoenvironmental indications 348 Chapter 15. Conclusions 352 References 356 Appendices 369 Appendix 1: Dentition measurements of all thylacoleonid specimens from Riversleigh and of comparative specimens from other localities 369 Table A: Measurements of upper and lower cheekteeth for all species of Wakaleo 369 Table B: Upper cheek dentition measurements for species of Lekaneleo 371 Table C: Lower cheek dentition measurements for specimens of Lekaneleo roskellyae 371 Table D: Dentition measurements for specimens of Microleo attenboroughi 371 Table E: Comparative measurements of cranial dimensions of species of thylacoleonids 372 Table F: Comparative measurements of upper tooth rows and palate dimensions of Wakaleo hilmeri, W. vanderleueri, W. pitikantensis and Lekaneleo roskellyae 373 Table G: Dentary measurements of Wakaleo hilmeri, W. oldfieldi, W. vanderleueri and Lekaneleo roskellyae (mm) 373 Appendix 2: Comparative specimens used in postcranial and functional morphological studies 374 Appendix 3: Specimens used in intrafamilial and interfamilial phylogenetic analyses 377 Appendix 4: Nodal apomorphies for most- parsimonious trees from intrafamilial analysis: A. unordered-character states; B. terminal taxa; C. ordered character- states 379 Appendix 5: Nodal apomorphies for most-parsimonious trees from interfamilial analysis: A. unordered character states; B. ordered character-states 388 Appendix 6: Publications……………………………………..in sleeve on back page vi Gillespie, A. 1997. Priscileo roskellyae sp.nov. (Thylacoleonidae, Marsupialia) from the Oligocene-Miocene of Riversleigh, northwestern Queensland). Memoirs of the Queensland Museum. 41(2): 321-327. Wroe, S., Myers, T.J., Wells, R.T. and Gillespie, A. 1999. Estimating the weight of the Pleistocene marsupial lion, Thylacoleo carnifex (Thylacoleonidae: Marsupialia): implications for the ecomorphology of a marsupial super-predator and hypotheses of impoverishment of Australian marsupial carnivore faunas. Australian Journal of Zoology. 47: 489-498. Archer, M., Arena, R., Bassarova, M., Black, K., Brammall, J., Cooke, B., Creaser, P., Crosby, K., Gillespie, A., Godthelp, H., Gott, M., Hand, S.J., Kear, B., Krikmann, A., Mackness, B., Muirhead, J., Musser, A., Myers, T., Pledge, N., Wang, Y., and Wroe S. 1999. The evolutionary history and diversity of Australian mammals. Australian Mammalogy. 21: 1-45. vii LIST OF FIGURES Fig. 3.1 Distribution of fossil sites yielding thylacoleonid species 11 Fig. 4.1 Priscileo pitikantensis, SAM P37719 holotype 20 Fig. 4.2 Comparative measurements of maxilla alveoli and M2s of SAM P37719 and Riversleigh specimens 20 Fig. 4.3 Cranium of Wakaleo hilmeri sp. nov., QM F45200 holotype, dorsal view 30 Fig. 4.4 Cranium of Wakaleo hilmeri, QM F45200, profile view 32 Fig. 4.5 Cranium of Wakaleo hilmeri, QM F45200, ventral view 37 Fig. 4.6 Cranial measurements of Wakaleo hilmeri, QM F45200 42 Fig. 4.7 Occiput of Wakaleo hilmeri, QM F45200 46 Fig. 4.8 Left basicranial region of Wakaleo hilmeri, QM F45200 49 Fig. 4.9 Wakaleo hilmeri, QM F23443, palate; Rackham’s Low Lion Site 49 Fig. 4.10 Wakaleo hilmeri, QM F45200, left cheek dentition 54 Fig. 4.11 Wakaleo hilmeri, AR 19249, right dentary; a. lingual; b. buccal; c. measurements 59 Fig. 4.12 Wakaleo hilmeri, AR 19249; a. paired dentaries; b. left dentary, stereo occlusal view 62 Fig. 5.1 Wakaleo hilmeri cervical vertebra 80 Fig. 5.2 Wakaleo hilmeri lumbar vertebra 80 Fig. 5.3 Wakaleo hilmeri lumbar vertebrae 80 Fig. 5.4 Wakaleo hilmeri sacrum 80 Fig. 5.5 Wakaleo hilmeri ilia 89 Fig. 5.6 Wakaleo hilmeri humerus 92 Fig. 5.7 Humeri of Wakaleo hilmeri and Wakaleo pitikantensis 92 Fig. 5.8 Thylacoleonid humeri, anterior view 94 Fig. 5.9 Wakaleo hilmeri radius 98 Fig. 5.10 Radii of species of Wakaleo and Thylacoleo carnifex 98 Fig. 5.11 Wakaleo hilmeri ulna 101 Fig. 5.12 Wakaleo hilmeri unciform 104 Fig. 5.13 Wakaleo hilmeri trapezium 104 Fig. 5.14 Wakaleo hilmeri metacarpal I 110 Fig. 5.15 Wakaleo hilmeri proximal phalanges: A. right proximal phalanx digit; B. left pollex, proximal phalanx 110 Fig. 5.16 Wakaleo hilmeri left pollex and right digit II 110 Fig. 5.17 Wakaleo hilmeri calcaneum 114 Fig. 5.18 Wakaleo pitikantensis (SAM P37720) scapula 114 Fig. 6.1 Wakaleo sp. cf. W. hilmeri, QM F23446, occlusal view 120 Fig. 6.2 Wakaleo sp. cf. W. hilmeri, QM F23446, profile view 120 Fig. 6.3 Wakaleo sp. cf. W. hilmeri, QM F23446, measurements of maxilla 120 Fig.