Troy J. Myers

Prediction of marsupial body mass

Cranio-dental variables are correlated with body mass in marsupials, using a species data-set derived from extant australidelphian representatives, to predict body mass in fossil species. Thirty-eight extant australidelphian species, including 10 dasyuromorphians, 22 diprotodontians, 1 notoryctomorphian and 5 peramelemorphians, were analysed. Where sexual dimorphism was prominent, genders were evaluated separately. Twenty-nine cranio-dental variables were measured for each specimen and species averages calculated. Body masses were taken as recorded for each specimen or as published species averages. The cranio-dental measures for each morpho-species were then regressed against average body mass in four distinct data-sets: (1) the entire species sample, (2) only dasyuromorphian taxa, (3) only diprotodontians, and (4) all species excluding dasyuromorphians. Each cranio-dental variable was then ranked according to various error statistics and correlation coefficients. Results suggest that predictors of body size in eutherians (such as first lower molar area), commonly used to estimate body mass in marsupials may not be reliable or accurate indicators. Significant differences in the usefulness of predictor variables between taxonomic data-sets were also observed. Total jaw length is the most reliable predictor for diprotodontians, as well as for all species combined, whereas lower molar row length appears to be more appropriate for dasyuromorphians. Multiple variable regressions variably offer more precision than those derived from individual parameters. On the basis of these data, body mass estimations are provided for a number of extinct marsupial taxa.

An alternative method for predicting body mass: the case of the Pleistocene marsupial lion

Abstract Accurate estimates of body mass in fossil taxa are fundamental to paleobiological reconstruction. Predictive equations derived from correlation with craniodental and body mass data in extant taxa are the most commonly used, but they can be unreliable for species whose morphology departs widely from that of living relatives. Estimates based on proximal limb-bone circumference data are more accurate but are inapplicable where postcranial remains are unknown. In this study we assess the efficacy of predicting body mass in Australian fossil marsupials by using an alternative correlate, endocranial volume. Body mass estimates for a species with highly unusual craniodental anatomy, the Pleistocene marsupial lion (Thylacoleo carnifex), fall within the range determined on the basis of proximal limb-bone circumference data, whereas estimates based on dental data are highly dubious. For all marsupial taxa considered, allometric relationships have small confidence intervals, and percent prediction errors are comparable to those of the best predictors using craniodental data. Although application is limited in some respects, this method may provide a useful means of estimating body mass for species with atypical craniodental or postcranial morphologies and taxa unrepresented by postcranial remains. A trend toward increased encephalization may constrain the methods predictive power with respect to many, but not all, placental clades.

Osteological morphometrics of Australian chelonioid turtles.

Abstract Extant and fossil Australian chelonioid turtles were examined for 57 osteological morphometric variables. Data were analysed using principal components analysis and canonical variates analysis, after Burnaby isometric ‘size’ removal, as well as multivariate allometry. Results indicate that Lepidochelys spp. are proportionately differentiated from other Cheloniidae. The majority of chelonioid osteological variables scale isometrically, with less than a third exhibiting positive or negative allometry. Skull length and width, postero-ventral skull, mandible length, scapular and pubic variables are found to be useful for differentiating between extant and extinct chelonioids. Skull length and width, mandible height, jaw symphysis length, premaxilla height, femoral length, scapular, pelvic, plastral and rib variables are established as useful differentiators of cheloniids. Australian fossil protostegids are morphometrically more similar to cheloniids than dermochelyids, and no cranial morphometric evidence could be found for the presence of more than one protostegid species. Some osteological allometric variables may be valuable for use in determining the relationships of chelonioids; however these should be examined in conjunction with morphology-based cladistic analyses to test established phylogenies.

A new Miocene carnivorous marsupial, Barinya kutjamarpensis (Dasyuromorphia), from central Australia

Binfield, P., Archer, M., Hand, S.J., Black, K.H., Myers, T.J., Gillespie, A.K. & Arena, D.A., June 2016. A new Miocene carnivorous marsupial, Barinya kutjamarpensis (Dasyuromorphia), from central Australia. Alcheringa 41, xx–xx. ISSN 0311-5518. A new dasyuromorphian, Barinya kutjamarpensis sp. nov., is described on the basis of a partial dentary recovered from the Miocene Wipajiri Formation of northern South Australia. Although about the same size as the only other species of this genus, B. wangala from the Miocene faunal assemblages of the Riversleigh World Heritage Area, northwestern Queensland, it has significant differences in morphology including a very reduced talonid on M4 and proportionately wider molars. Based on the structural differences and the more extensive wear on its teeth, the central Australian species might have consumed harder or more abrasive prey in a more silt-rich environment than its congener, which hunted in the wet early to middle Miocene forests of Riversleigh. Pippa Binfield [pippa.binfield@outlook.com], Michael Archer [m.archer@unsw.edu.au], Suzanne J. Hand [s.hand@unsw.edu.au], Karen H. Black [k.black@unsw.edu.au], Troy J. Myers [t.myers@unsw.edu.au] Anna K. Gillespie [a.gillespie@unsw.edu.au] and Derrick A. Arena [rick@sitc.net.au], PANGEA Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales 2052, Sydney, Australia.

Miminipossum notioplanetes, a Miocene forest-dwelling phalangeridan (Marsupialia; Diprotodontia) from northern and central Australia

Miminipossum notioplanetes represents a new Early/Middle Miocene family (Miminipossumidae) of phalangeridan possums recovered from the Two Trees Local Fauna from the Riversleigh World Heritage area in northwestern Queensland and the Kutjamarpu Local Fauna of the Tirari Desert in northern South Australia. Because of widespread convergence in key features of P3 and M1 among phalangeridan families, the interfamilial relationships of Miminipossumidae are uncertain. The age of the Kutjamarpu Local Fauna has been in doubt with estimates ranging from Late Oligocene to Middle Miocene. The new taxon raises to 15 the number of taxa in the Kutjamarpu Local Fauna that are shared with both Riversleigh’s Faunal Zone B (Early Miocene) and Riversleigh’s Faunal Zone C (Middle Miocene) assemblages. Although there is relatively little biocorrelative support for the estimate of a Late Oligocene age, doubt remains about whether the age is more likely to be Early or Middle Miocene. In terms of palaeoenvironmental implications, because both Riversleigh’s Early and Middle Miocene assemblages have been concluded to have accumulated in temperate, wet, species-rich lowland forests, the same or similar Early/Middle Miocene palaeoenvironments may well have extended into central Australia at the time when the Kutjamarpu assemblage was accumulating. Michael Archer. Palaeontology, Geobiology and Earth Archives Research Centre (PANGEA), School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia; m.archer@unsw.edu.au Pippa Binfield. Palaeontology, Geobiology and Earth Archives Research Centre (PANGEA), School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia; pippa.binfield@outlook.com http://zoobank.org/F2286DA9-B627-46E3-A12F-AEB719B904A8 Archer, Michael, Binfield, Pippa, Hand, Suzanne J., Black, Karen H., Creaser, Phillip, Myers, Troy J., Gillespie, Anna K., Arena, Derrick A., Scanlon, John, Pledge, Neville, and Thurmer, Jenni. 2018. Miminipossum notioplanetes, a Miocene forest-dwelling phalangeridan (Marsupialia; Diprotodontia) from northern and central Australia. Palaeontologia Electronica 21.1.2A: 1-11. https://doi.org/10.26879/757 palaeo-electronica.org/content/2018/2109-new-family-of-marsupials Copyright: January 2018 Palaeontology Association. This is an open access article distributed under the terms of Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0), which permits users to copy and redistribute the material in any medium or format, provided it is not used for commercial purposes and the original author and source are credited, with indications if any changes are made. creativecommons.org/licenses/by-nc-sa/4.0/ ARCHER ET AL.: NEW FAMILY OF MARSUPIALS Suzanne J. Hand. Palaeontology, Geobiology and Earth Archives Research Centre (PANGEA), School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia; s.hand@unsw.edu.au Karen H. Black. Palaeontology, Geobiology and Earth Archives Research Centre (PANGEA), School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia; k.black@unsw.edu.au Phillip Creaser. Palaeontology, Geobiology and Earth Archives Research Centre (PANGEA), School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia; philcreaser@grapevine.com.au Troy J. Myers. Palaeontology, Geobiology and Earth Archives Research Centre (PANGEA), School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia; t.myers@unsw.edu.au Anna K. Gillespie. Palaeontology, Geobiology and Earth Archives Research Centre (PANGEA), School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia; a.gillespie@unsw.edu.au Derrick A. Arena. Palaeontology, Geobiology and Earth Archives Research Centre (PANGEA), School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia; r.arena@unsw.edu.au John Scanlon. Outback at Isa, Mount Isa, Queensland 4825, Australia; nanowana@gmail.com Neville Pledge. Palaeontology, South Australian Museum, North Terrace, Adelaide 5000, Australia; Neville.Pledge@samuseum.sa.gov.au Jenni Thurmer. Palaeontology, South Australian Museum, North Terrace, Adelaide 5000, Australia; jthurmer@senet.com.au

The identification of Oligo-Miocene mammalian palaeocommunities from the Riversleigh World Heritage Area, Australia and an appraisal of palaeoecological techniques

Fourteen of the best sampled Oligo-Miocene local faunas from the Riversleigh World Heritage Area, north-western Queensland, Australia are analysed using classification and ordination techniques to identify potential mammalian palaeocommunities and palaeocommunity types. Abundance data for these faunas are used, for the first time, in conjunction with presence/absence data. An early Miocene Faunal Zone B and two middle Miocene Faunal Zone C palaeocommunities are recognised, as well as one palaeocommunity type. Change in palaeocommunity structure, between the early Miocene and middle Miocene, may be the result of significant climate change during the Miocene Carbon Isotope Excursion. The complexes of local faunas identified will allow researchers to use novel palaeocommunities in future analyses of Riversleigh’s fossil faunas. The utility of some palaeoecological multivariate indices and techniques is examined. The Dice index is found to outperform other binary similarity/distance coefficients, while the UPGMA algorithm is more useful than neighbour joining. Evidence is equivocal for the usefulness of presence/absence data compared to abundance.