Kenny J. Travouillon

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World Heritage Area have been compiled by review of recorded occurrences of taxa obtained from both published and unpublished sources.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.

The use of MSR (Minimum Sample Richness) for sample assemblage comparisons

Abstract Minimum Sample Richness (MSR) is defined as the smallest number of taxa that must be recorded in a sample to achieve a given level of inter-assemblage classification accuracy. MSR is calculated from known or estimated richness and taxonomic similarity. Here we test MSR for strengths and weaknesses by using 167 published mammalian local faunas from the Paleogene and early Neogene of the Quercy and Limagne area (Massif Central, southwestern France), and then apply MSR to 84 Oligo-Miocene faunas from Riversleigh, northwestern Queensland, Australia. In many cases, MSR is able to detect the assemblages in the data set that are potentially too incomplete to be used in a similarity-based comparative taxonomic analysis. The results show that the use of MSR significantly improves the quality of the clustering of fossil assemblages. We conclude that this method can screen sample assemblages that are not representative of their underlying original living communities. Ultimately, it can be used to identify which assemblages require further sampling before being included in a comparative analysis.

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

Earliest modern bandicoot and bilby (Marsupialia, Peramelidae and Thylacomyidae) from the Miocene of the Riversleigh World Heritage Area, northwestern Queensland, Australia

ABSTRACT Recent molecular phylogenies of peramelemorphians suggest that thylacomyids (bilbies) and peramelids (modern bandicoots) diversified sometime in the late Oligocene or early Miocene. Until now, however, the earliest fossil evidence of thylacomyids and peramelids was from the Australian Pliocene. Here we describe the oldest peramelid and thylacomyid from the middle Miocene of the Riversleigh World Heritage Area, northwestern Queensland. The peramelid, Crash bandicoot, gen. et sp. nov., is represented by a single maxilla containing M1–3 that exhibits peramelid synapomorphies, including development of a metaconular hypocone, an incomplete centrocrista, and well-developed anterior cingulum. The thylacomyid, Liyamayi dayi, gen. et sp. nov., is represented by M2 and m1, which show thylacomyid synapomorphies including a conical entoconid, a conical stylar cusp B (StB) and StD, and reduced distance between the metastyle and StD. The results of our phylogenetic analysis indicate that both species are part of crown-group Peramelemorphia

Finding the Minimum Sample Richness (MSR) for multivariate analyses: implications for palaeoecology

Many techniques have been developed to estimate species richness and beta diversity. Those techniques, dependent on sampling, require abundance or presence/absence data. Palaeontological data is by nature incomplete, and presence/absence data is often the only type of data that can be used to provide an estimate of ancient biodiversity. We used a simulation approach to investigate the behaviour of commonly used similarity indices, and the reliability of classifications derived from these indices, when working with incomplete data. We drew samples, of varying number and richness, from artificial species lists, which represented original life assemblages, and calculated error rates for classifications of the parent lists and samples. Using these results, we estimated the Minimum Sample Richness (MSR) needed to achieve 95% classification accuracy. Results were compared for classifications derived from several commonly used similarity indexes (Dice, Jaccard, Simpson and Raup–Crick). MSR was similar for the Dice, Jaccard and Simpson indices. MSR for the Raup–Crick index was often much lower, suggesting that it is preferable for classifying patchy data, however the performance of this index was less stable than the other three in the simulations, which required an even lower MSR. MSR can be found for all presence/absence data from the contour graphs and equations as long as the absolute species richness and the beta diversity can be estimated.

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 New Species of the Basal "Kangaroo'' Balbaroo and a Re-Evaluation of Stem Macropodiform Interrelationships

Exceptionally well-preserved skulls and postcranial elements of a new species of the plesiomorphic stem macropodiform Balbaroo have been recovered from middle Miocene freshwater limestone deposits in the Riversleigh World Heritage Area of northwestern Queensland, Australia. This constitutes the richest intraspecific sample for any currently known basal “kangaroo”, and, along with additional material referred to Balbaroo fangaroo, provides new insights into structural variability within the most prolific archaic macropodiform clade – Balbaridae. Qualitative and metric evaluations of taxonomic boundaries demonstrate that the previously distinct species Nambaroo bullockensis is a junior synonym of B. camfieldensis. Furthermore, coupled Maximum Parsimony and Bayesian phylogenetic analyses reveal that our new Balbaroo remains represent the most derived member of the Balbaroo lineage, and are closely related to the middle Miocene B. camfieldensis, which like most named balbarid species is identifiable only from isolated jaws. The postcranial elements of Balbaroo concur with earlier finds of the stratigraphically oldest balbarid skeleton, Nambaroo gillespieae, and suggest that quadrupedal progression was a primary gait mode as opposed to bipedal saltation. All Balbaroo spp. have low-crowned bilophodont molars, which are typical for browsing herbivores inhabiting the densely forested environments envisaged for middle Miocene northeastern Australia.

Ganguroo robustiter, sp. nov. (Macropodoidea, Marsupialia), a middle to early late Miocene basal macropodid from Riversleigh World Heritage Area, Australia

ABSTRACT Cranial and dental remains of the middle to early late Miocene macropodid kangaroo, Ganguroo robustiter, sp. nov., are described. Postcranial remains of G. robustiter were previously described as referable to G. bilamina. Ganguroo robustiter is more robust (approximately 20% larger) and more derived than G. bilamina and G. bites, in having a larger m4, a well-developed posterolingual ridge and lingual cingulum on P3, a longer P3/p3, and no stylar cusp C on M3–M4. We used previously published data matrices to analyze the phylogenetic relationship of G. robustiter. Both phylogenetic analyses, using craniodental and postcranial characters, place G. robustiter within Macropodidae, as the sister taxon to sthenurines and macropodines. Species of Ganguroo are not found to be monophyletic despite their extreme similarity in character scores. This may be due to the large amount of missing data for G. bilamina and G. bites for which no postcranial remains have been identified. Phylogenetic results are ambiguous, recovering unresolved trees with low bootstrap values, but the generic assignment of these taxa is maintained because they are remarkably similar. Species of Ganguroo may represent a phyletic lineage, with species increasing in size and losing cusp/cuspids on their premolars through time, which appears to coincide with a broader record of changing vegetation and climates through the middle Miocene.