Jeanette Muirhead

Current status of species-level representation in faunas from selected fossil localities in the Riversleigh World Heritage Area, northwestern Queensland

Current lists of species-level representation in faunas from 80 Cenozoic fossil localities at the Riversleigh World Heritage Area have been compiled by review of recorded occurrences of taxa obtained from both published and unpublished sources. More than 290 species-level taxa are represented, comprising mammals, amphibians, reptiles, birds, fishes, molluscs and crustaceans. The data are presented for the purpose of ongoing palaeoecological and biochronological studies.

CLADISTIC ANALYSIS OF DASYUROMORPHIAN (MARSUPIALIA) PHYLOGENY USING CRANIAL AND DENTAL CHARACTERS

Abstract Dasyuromorphian relationships were investigated using cladistic analysis for 24 species using 77 cranial and dental features. Among the 7 extinct taxa used were 6 recently described fossil species, each well represented by cranial and dental material (3 ameridelphians, 1 peramelemorphian, and 2 dasyuromorphians). Monophyly for the Dasyuromorphia and several clades widely recognized therein is supported, but in many instances, relationships among extant dasyurids departs greatly from general consensus. Where congruence with previous investigations is evident, few taxa are united by unique synapomorphies within Marsupialia. Many clades are united by combinations of locally derived features only. Bootstrap and Bremer support is weak for most clades. Thus, although supported by cladistic analysis, the status of many synapomorphies identified in the course of this study are tentative. However, for some groups, notably Dasyuridae and a dasyurid clade inclusive of all modern subfamilies, the synapomorphic nature of some derived features appears to be robust, even where they also are present in some outgroup taxa. This argument applies to shared apomorphies of the basicranium in particular. No potential sister taxon to Dasyuromorphia is favored. The case for australidelphian and microbiotheriid affinity of some American and Antarctic fossil taxa was considered to be highly equivocal.

A new genus and species, Badjcinus turnbulli (Thylacinidae: Marsupialia), from the late Oligocene of Riversleigh, northern Australia, and an investigation of thylacinid phylogeny

ABSTRACT Badjcinus turnbulli, gen. et sp. nov., is described from dental and incomplete skull material that includes the only pre-Pliocene dasyuromorphian basicranium described to date. Phylogenetic analysis places B. turnbulli basally within the Thylacinidae, but with autapomorphies. The relationship of B. turnbulli to other thylacines is assessed. The breadth of thylacinid diversity evident during the middle Tertiary argues for an earlier origin for the family than that suggested by molecular-based investigations. An amended diagnosis of the Thylacinidae is presented and thylacinid diversity and ecology is discussed.

Yarala burchfieldi, a plesiomorphic bandicoot (Marsupialia, Peramelemorphia) from Oligo-Miocene deposits of Riversleigh, northwestern Queensland

Yarala burchfieldi n. gen. and sp. is described from Oligo-Miocene deposits of Riversleigh Station, northwestern Queensland. Although the smallest and most plesiomorphic bandicoot known, it shares unique synapomorphies with other peramelemorphs, such as the posteriorly orientated preparacrista on M 2 , posterolingual location of the hypoconulids, and the buccal position of the centrocrista. However, Y. burchfieldi lacks synapomorphies that would unambiguously allow it to be placed in any of the modern families as currently understood. In its plesiomorphic features, Y. burchfieldi provides a structural link between peramelemorphs and dasyuromorphs and appears to be a descendant of an annectant group that separated long prior to the origin of “typical” bandicoots. This species is present in many sites within the Riversleigh area. It possibly filled an insectivorous-carnivorous niche presently occupied by small dasyurids that are relatively more abundant today than they were when the Riversleigh deposits accumulated.

YARALOIDEA (MARSUPIALIA, PERAMELEMORPHIA), A NEW SUPERFAMILY OF MARSUPIAL AND A DESCRIPTION AND ANALYSIS OF THE CRANIUM OF THE MIOCENE YARALA BURCHFIELDI

Abstract The skull of the Miocene Yarala burchfieldi Muirhead and Filan, 1995, is described. Analysis of skull morphology supports phylogenetic conclusions based on dental morphology. Y. burchfieldi shares a number of synapomorphies with other peramelemorphians, some of which are unique and help to define this order of marsupials. Y. burchfieldi is the most plesiomorphic peramelemorphian known. Although sharing some derived characters with a number of extant taxa, Y. burchfieldi lacks synapomorphies that unite all other peramelemorphian taxa as the Superfamily Perameloidea. The Yaraloidea and Yaralidae, a new superfamily and family of peramelemorphians, is proposed and diagnosed on the basis of Y. burchfieldi. Fossil evidence supports the late divergence of perameloids, while peramelemorphian diversity in the Tertiary indicates an ancient derivation for the order.

An exceptionally well-preserved short-snouted bandicoot (Marsupialia; Peramelemorphia) from Riversleigh's Oligo-Miocene deposits, northwestern Queensland, Australia

ABSTRACT We describe Galadi speciosus, gen. et sp nov., the second peramelemorphian (Yarala burchfieldi being the first) to be described from Oligo-Miocene deposits of Riversleigh World Heritage Property, northwestern Queensland. G. speciosus is represented by relatively complete craniodental material, including an exceptionally well-preserved skull. This taxon exhibits several apomorphies that clearly place it in the order Peramelemorphia, but it appears to be more plesiomorphic than any modern bandicoot. We present the first morphological phylogenetic analyses of Peramelemorphia, using 51 craniodental characters. Our analyses recover Yarala and Galadi speciosus outside crown group Peramelemorphia, with G. speciosus weakly supported as the sister taxon of the crown group. The craniodental morphology of G. speciosus, particularly its robust skull and proportionately short and broad snout, suggests that it filled a different ecological niche to extant bandicoots. We hypothesize that G. speciosus occupied a predominantly faunivorous, dasyurid-like niche in the Oligo-Miocene rainforests of Riversleigh, at a time when dasyurids appear to have been relatively rare.

Biogeographical implications of a new mouse-sized fossil bandicoot (Marsupialia: Peramelemorphia) occupying a dasyurid-like ecological niche across Australia

We describe Bulungu palara gen. et sp. nov., a new fossil peramelemorphian (bandicoot), based on a single well-preserved skull and additional dental specimens from Late Oligocene to Middle Miocene (Faunal Zones A–C) limestone deposits at the Riversleigh World Heritage Property, Queensland, and two dental specimens from the Early–Middle Miocene Kutjamarpu Local Fauna, South Australia. This is the first fossil peramelemorphian species to be reported from more than a single fossil fauna, with its inferred distribution extending from north-western Queensland (modern latitude ∼19°S) to north-eastern South Australia (modern latitude ∼28°S). The presence of Bulungu palara in Riversleigh Faunal Zones A, B and C and in the Kutjamarpu Local Fauna supports the current interpretation that these faunas span similar ages, namely Late Oligocene–Middle Miocene. Phylogenetic analyses of an expanded 74 morphological character dataset using maximum parsimony and Bayesian approaches, both with and without a molecular scaffold, consistently place Bulungu and the Oligo-Miocene forms Galadi and Yarala outside crown-group Peramelemorphia. These analyses also fail to support a close relationship between the Pliocene Ischnodon australis (previously considered the oldest known representative of the extant peramelemorphian family Thylacomyidae) and the modern thylacomyid genus Macrotis. With an estimated body mass of ∼130 g, Bulungu palara is smaller than any known Recent bandicoot from Australia, although some modern New Guinean species are similar in size. The small size and craniodental morphology of B. palara suggest that it was predominantly or exclusively insectivorous, perhaps ecologically similar to small New Guinean dasyurids such as Murexechinus melanurus. Together with the small-bodied (< 100 g), insectivorous Yarala burchfieldi and large-bodied (∼900 g), faunivorous Galadi speciosus, Bulungu palara demonstrates that Oligo-Miocene Australian peramelemorphians filled ecological niches that today are mostly occupied by dasyurids, and that a major faunal turnover event occurred at some point after the Middle Miocene. http://zoobank.org/urn:lsid:zoobank.org:pub:18955DCC-DB8C-4216-AF38-921E1E5C1F79

Sexually Dimorphic Bandicoots (Marsupialia: Peramelemorphia) From the Oligo-Miocene of Australia, First Cranial Ontogeny for Fossil Bandicoots and New Species Descriptions

Peramelemorphians (bandicoots and bilbies) are unique among mammals in having the shortest gestation period. Very little is known about their evolutionary history primarily because until recently their fossil record was scarce. Here we describe two new species, Madju variae, gen. et sp. nov., from late Oligocene to middle Miocene deposits from the Riversleigh World Heritage Area, Queensland, and the Kutjamarpu Local Fauna, South Australia, and Madju encorensis, gen. et sp. nov., also from Riversleigh WHA but from the late middle to early late Miocene. Phylogenetic analysis suggests that they are best regarded as basal members of the Superfamily Perameloidea. Species of Madju are unusual in showing a distinct reduction in size through time, possibly reflecting environmental change from the early to late Miocene. Madju variae is the first-known sexually dimorphic fossil peramelemorphian. The preservation and representation of specimens of M. variae is exceptional, enabling documentation of ontogenetic development from juvenile to old adult stage suggesting that juveniles of M. variae developed more slowly than their modern counterparts and that lactation lasted for a longer time. If so, the short gestation of modern peramelemorphians would appear to be a specialisation that might have evolved sometime after the middle Miocene.

The genus Galadi: three new bandicoots (Marsupialia, Peramelemorphia) from Riversleigh’s Miocene deposits, northwestern Queensland, Australia

ABSTRACT We describe three new bandicoot species of the genus Galadi from the Miocene of Riversleigh World Heritage Area in northern Australia. The first species, which is represented by a complete dentary and several isolated upper molars, is restricted to Riversleighs Faunal Zone B. It is the largest bandicoot as yet known from Riversleigh. The second species is represented by 19 specimens, including a partial skull and several maxillae and dentaries, from Riversleighs Faunal Zone C. Several features distinguishing this species from the similarly sized type species G. speciosus are of interest, notably the presence of larger maxillopalatine fenestrae and additional maxillary fenestrae, incomplete centrocrista on all upper molars, a more complete posterior cingulum on upper molars, and higher degree of dental wear, which together suggest a more omnivorous diet. The third species is represented by a single maxillary, which exhibits a quite different combination of dental features compared with other Galadi species. All Galadi species appear to be restricted to Riversleighs Faunal Zones B and C, which are interpreted to be early and middle Miocene in age, respectively, with rainforest habitats persisting throughout. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

A review of the Pliocene bandicoots of Australia, and descriptions of new genus and species

ABSTRACT The Pliocene fossil record of Australia has revealed the oldest known occurrences of modern peramelemorphian (bandicoot and bilbies) genera such as Perameles, cf. Peroryctes, and Chaeropus. Recent phylogenetic analyses based on morphology have questioned the previously accepted understanding about generic relationships of some of these Pliocene taxa. These doubts limit our ability to develop independent divergence models based on molecular data because they depend on fossil records in order to calibrate minimum rates of change. Hence, there is a need to critically review the Pliocene fossil record. To this end, we have examined Pliocene specimens of peramelemorphians in museum collections across Australia and performed a comprehensive phylogenetic analysis based on dental and cranial morphology to review and accordingly revise subfamilial taxonomy. As part of this revision, we describe here two new species, one from the Chinchilla Local Fauna (LF) in Queensland (Perameles wilkinsonorum, sp. nov.) and one from both the Big Sink LF in the Wellington Caves area and the Bow LF in New South Wales (Silvicultor karae, gen. et sp. nov.). We reassign the two ‘Peroryctes’ species from Hamilton LF, Victoria, to a new genus (Silvicultor). We summarize the distribution of peramelemorphians during the Pliocene and show how climate change appears to have shaped their subsequent Quaternary distribution.