Timothy F. Flannery

Dinosaurs, dragons, and dwarfs: the evolution of maximal body size.

Among local faunas, the maximum body size and taxonomic affiliation of the top terrestrial vertebrate vary greatly. Does this variation reflect how food requirements differ between trophic levels (herbivores vs. carnivores) and with taxonomic affiliation (mammals and birds vs. reptiles)? We gathered data on the body size and food requirements of the top terrestrial herbivores and carnivores, over the past 65,000 years, from oceanic islands and continents. The body mass of the top species was found to increase with increasing land area, with a slope similar to that of the relation between body mass and home range area, suggesting that maximum body size is determined by the number of home ranges that can fit into a given land area. For a given land area, the body size of the top species decreased in the sequence: ectothermic herbivore > endothermic herbivore > ectothermic carnivore > endothermic carnivore. When we converted body mass to food requirements, the food consumption of a top herbivore was about 8 times that of a top carnivore, in accord with the factor expected from the trophic pyramid. Although top ectotherms were heavier than top endotherms at a given trophic level, lower metabolic rates per gram of body mass in ectotherms resulted in endotherms and ectotherms having the same food consumption. These patterns explain the size of the largest-ever extinct mammal, but the size of the largest dinosaurs exceeds that predicted from land areas and remains unexplained.

Late-surviving megafauna in Tasmania, Australia, implicate human involvement in their extinction

Establishing the cause of past extinctions is critical if we are to understand better what might trigger future occurrences and how to prevent them. The mechanisms of continental late Pleistocene megafaunal extinction, however, are still fiercely contested. Potential factors contributing to their demise include climatic change, human impact, or some combination. On the Australian mainland, 90% of the megafauna became extinct by ≈46 thousand years (ka) ago, soon after the first archaeological evidence for human colonization of the continent. Yet, on the neighboring island of Tasmania (which was connected to the mainland when sea levels were lower), megafaunal extinction appears to have taken place before the initial human arrival between 43 and 40 ka, which would seem to exonerate people as a contributing factor in the extirpation of the island megafauna. Age estimates for the last megafauna, however, are poorly constrained. Here, we show, by direct dating of fossil remains and their associated sediments, that some Tasmanian megafauna survived until at least 41 ka (i.e., after their extinction on the Australian mainland) and thus overlapped with humans. Furthermore, a vegetation record for Tasmania spanning the last 130 ka shows that no significant regional climatic or environmental change occurred between 43 and 37 ka, when a land bridge existed between Tasmania and the mainland. Our results are consistent with a model of human-induced extinction for the Tasmanian megafauna, most probably driven by hunting, and they reaffirm the value of islands adjacent to continental landmasses as tests of competing hypotheses for late Quaternary megafaunal extinctions.

Evidence that monotremes and ausktribosphenids are not sistergroups

THOMAS H. RICH1, TIMOTHY F. FLANNERY2, PETER TRUSLER3, LESLEY KOOL4, NICHOLAS A. VAN KLAVEREN5, and PATRICIA VICKERS-RICH4 1Museum Victoria, P.O. Box 666E, Melbourne, Victoria 3001, Australia, trich@museum.vic.gov.au; 2South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia; 39 Whitehorse Road, Blackburn, Victoria 3130, Australia; 4Earth Sciences Department, Monash University, Clayton, Victoria 3800, Australia; 51/6 Lucerne Avenue, Mornington, Victoria 3931, Australia

Ecological and evolutionary significance of sizes of giant extinct kangaroos

A method, based on femoral circumference, allowed us to develop body mass estimates for 11 extinct Pleistocene megafaunal species of macropodids (Protemnodon anak, P. brehus, P. hopei, P. roechus, Procoptodon goliah, ‘P.’ gilli, Simosthenurus maddocki, S. occidentalis, Sthenurus andersoni, S. stirlingi and S. tindalei) and three fossil populations of the extant eastern grey kangaroo (Macropus giganteus). With the possible exception of P. goliah, the extinct taxa were browsers, among which sympatric, congeneric species sort into size classes separated by body mass increments of 20–75%. None show evidence of size variation through time, and only the smallest (‘P.’ gilli) exhibits evidence suggestive of marked sexual dimorphism. The largest surviving macropodids (five species of Macropus) are grazers which, although sympatric, do not differ greatly in body mass today, but at least one species (M. giganteus) fluctuated markedly in body size over the course of the Pleistocene. Sexual dimorphism in these species is marked, and may have varied through time. There is some mass overlap between the extinct and surviving macropodid taxa. With a mean estimated body mass of 232 kg, Procoptodon goliah was the largest hopping mammal ever to exist.

An Australian Multituberculate and Its Palaeobiogeographic Implications

A dentary fragment containing a tiny left plagiaulacoid fourth lower premolar from the Early Cretaceous (Aptian) of Victoria provides the first evidence of the Multituberculata from Australia. This unique specimen represents a new genus and species, Corriebaatar marywaltersae, and is placed in a new family, Corriebaataridae. The Australian fossil, together with meagre records of multituberculates from South America, Africa, and Madagascar, reinforces the view that Multituberculata had a cosmopolitan distribution during the Mesozoic, with dispersal into eastern Gondwana probably occurring prior to enforcement of climatic barriers (indicated by marked differentiation in regional floras) in the Early Cretaceous.

IMPLICATIONS OF A NEW SPECIES OF THE OLIGO-MIOCENE KANGAROO (MARSUPIALIA: MACROPODOIDEA) NAMBAROO, FROM THE RIVERSLEIGH WORLD HERITAGE AREA, QUEENSLAND, AUSTRALIA

Abstract A partial skeleton (including both skull and postcranium) and referred dental material attributable to a new species of Oligo-Miocene kangaroo, Nambaroo gillespieae, are described from the Riversleigh World Heritage Area, northwestern Queensland, Australia. The holotype specimen is one of the oldest articulated fossil kangaroo skeletons yet discovered and includes the first postcranial material definitively attributable to the extinct family Balbaridae. Functional-adaptive analysis (including comparisons with modern taxa) of the hindlimb and pedal elements suggests consistent use of quadrupedal progression rather than true hopping. Robust forelimbs and an opposable first pedal digit (lost in most macropodoids) might also indicate limited climbing ability. Cladistic analysis of 104 discrete cranio-dental and postcranial characters coded for 25 ingroup and one outgroup taxon places N. gillespieae in a plesiomorphic sister clade (also containing other Balbarids and the propleopine Ekaltadeta ima) to all other macropodoids. This result supports recent revisions to the classification of kangaroos, which recognize Balbaridae as the most basal macropodoid family-level taxon.

A new species of bandicoot, Microperoryctes aplini , from western New Guinea

A distinctive new striped bandicoot of the genus Microperoryctes ( M. aplini new species) is described and compared with Microperoryctes murina , another little-known bandicoot with which the new species has been confused in the past. The smallest of all living bandicoots, M. aplini is apparently restricted to high-elevation forests in the Arfak Mountains of the Vogelkop Peninsula of western New Guinea. The similarly small M. murina is known only from high-elevation forests on Gunung Sumuri, a peak in the Weyland Range of western New Guinea. The two species differ markedly in fur colour and ornamentation, pelage texture, external proportions, and quantitative and qualitative craniodental aspects, and may not be immediately related to one another.

NOTES ON THE PHALANGERID MARSUPIAL GENUS SPILOCUSCUS, WITH DESCRIPTION OF A NEW SPECIES FROM PAPUA

Abstract A new small-bodied species of spotted cuscus is described from Biak and Supiori, neighboring oceanic islands in Cenderawasih Bay, northwest New Guinea. The nonvolant mammal fauna of Biak-Supiori is almost entirely endemic. The geographic origin of another insular species of the genus (Spilocuscus kraemeri) is also discussed: S. kraemeri is a distinctive species known only from the Admiralty Islands but, due to its putative absence from the fossil record of those islands, it is thought to have been introduced there from an unknown source population in prehistoric times. Based on new evidence, we suggest that kraemeri is either native to the Admiralty Islands, or originally differentiated on the large island of New Britain in the Bismarck Archipelago.

The mandible and dentition of the Early Cretaceous monotreme Teinolophos trusleri

Rich, T.H., Hopson, J.A., Gill, P.G., Trusler, P., Rogers-Davidson, S., Morton, S., Cifelli, R.L., Pickering, D., Kool, L., Siu, K., Burgmann, F.A., Senden, T., Evans, A.R., Wagstaff, B.E., Seegets-Villiers, D., Corfe, I.J., Flannery, T.F., Walker, K., Musser, A.M., Archer, M., Pian, R. & Vickers-Rich, P., June 2016. The mandible and dentition of the Early Cretaceous monotreme Teinolophos trusleri. Alcheringa 40, xx–xx. ISSN 0311-5518. The monotreme Teinolophos trusleri Rich, Vickers-Rich, Constantine, Flannery, Kool & van Klaveren, 1999 from the Early Cretaceous of Australia is redescribed and reinterpreted here in light of additional specimens of that species and compared with the exquisitely preserved Early Cretaceous mammals from Liaoning Province, China. Together, this material indicates that although T. trusleri lacked a rod of postdentary bones contacting the dentary, as occurs in non-mammalian cynodonts and basal mammaliaforms, it did not share the condition present in all living mammals, including monotremes, of having the three auditory ossicles, which directly connect the tympanic membrane to the fenestra ovalis, being freely suspended within the middle ear cavity. Rather, T. trusleri appears to have had an intermediate condition, present in some Early Cretaceous mammals from Liaoning, in which the postdentary bones cum ear ossicles retained a connection to a persisting Meckel’s cartilage although not to the dentary. Teinolophos thus indicates that the condition of freely suspended auditory ossicles was acquired independently in monotremes and therian mammals. Much of the anterior region of the lower jaw of Teinolophos is now known, along with an isolated upper ultimate premolar. The previously unknown anterior region of the jaw is elongated and delicate as in extant monotremes, but differs in having at least seven antemolar teeth, which are separated by distinct diastemata. The dental formula of the lower jaw of Teinolophos trusleri as now known is i2 c1 p4 m5. Both the deep lower jaw and the long-rooted upper premolar indicate that Teinolophos, unlike undoubted ornithorhynchids (including the extinct Obdurodon), lacked a bill. Thomas H. Rich [trich@museum.vic.gov.au], Sally Rogers-Davidson [srogers@museum.vic.gov.au], David Pickering [dpick@museum.vic.gov.au], Timothy F. Flannery [tim.flannery@textpublishing.com.au], Ken Walker [kwalker@museum.vic.gov.au], Museum Victoria, PO Box 666, Melbourne, Victoria 3001, Australia; James A. Hopson [jhopson@uchicago.edu], Department of Organismal Biology & Anatomy, University of Chicago,1025 East 57th Street, Chicago, IL 60637, USA; Pamela G. Gill [pam.gill@bristol.ac.uk], School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, U.K. and Earth Science Department, The Natural History Museum, Cromwell Road, London SW7 5BD, UK; Peter Trusler [peter@petertrusler.com.au], Lesley Kool [koollesley@gmail.com], Doris Seegets-Villiers [doris.seegets-villiers@monash.edu], Patricia Vickers-Rich [pat.rich@monash.edu], School of Earth, Atmosphere and Environment, Monash University, Victoria 3800, Australia; Steve Morton [steve.morton@monash.edu], Karen Siu [karen.siu@monash.edu], School of Physics and Astronomy, Monash University, Victoria 3800, Australia; Richard L. Cifelli [rlc@ou.edu] Sam Noble Oklahoma Museum of Natural History, University of Oklahoma, Norman, OK 73072, USA; Flame A. Burgmann [flame.burgmann@monash.edu], Monash Centre for Electron Microscopy, 10 Innovation Walk, Monash University, Clayton, Victoria 3800, Australia; Tim Senden [Tim.Senden@anu.edu.au], Department of Applied Mathematics, Research School of Physical Sciences and Engineering, The Australian National University, Canberra, Australian Capital Territory 0200, Australia; Alistair R. Evans [alistair.evans@monash.edu], School of Biological Sciences, Monash University, Victoria 3800, Australia; Barbara E. Wagstaff [wagstaff@unimelb.edu.au], School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia; Ian J. Corfe [ian.corfe@helsinki.fi], Institute of Biotechnology, Viikinkaari 9, 00014, University of Helsinki, Finland; Anne M. Musser [anne.musser@austmus.gov.au], Australian Museum, 1 College Street, Sydney NSW 2010 Australia; Michael Archer [m.archer@unsw.edu.au], School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia; Rebecca Pian [rpian@amnh.org], Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192, USA. Received 7.4.2016; accepted 14.4.2016.

Evolution of Hind Limb Proportions in Kangaroos (Marsupialia: Macropodoidea)

Kangaroos (Macropodoidea: Marsupialia) are a characteristic group of Australo-New Guinean mammals that diversified during the geographic isolation of the Australian continent in the Cenozoic. They are first recorded in the Late Oligocene, although the clade diverged from other diprotodontians around 38 million years ago (mya; Westerman et al., 2002), with early forms perhaps resembling small arboreal ‘phalangerids’ (Flannery, 1982). Living macropodoids vary widely in body size ( 60 kg in larger species of Macropus), and show a high degree of ecological diversity. They include forms specialized for climbing (e.g., Dendrolagus), burrowing (e.g., Bettongia leseur), and occupation of closed rainforest/woodland (e.g., Hypsiprymnodon, Setonix) through to open temperate/tropical and/or arid zone grassland (e.g., Macropus). Despite this variability, the appendicular skeleton of macropodoids is remarkably conservative with all members of the group showing similar modifications (particularly in the long bones of the hind limb, tarsus, and pes) favoring a bipedal hopping gait. Windsor and Dagg (1971) standardized terminology for kangaroo locomotion designating ‘slow pentapedal progression’ as that involving synchronous use of the limbs and tail (present in all macropodoids and extensively used by species of Dorcopsis; Bourke, 1989), ‘walking’ as a gait involving asynchronous use of all limbs (confined to species of Dendrolagus; Windsor and Dagg, 1971), ‘quadrupedal bounding’ as movement employing synchronous use of all limbs (present in species of Dendrolagus, Windsor and Dagg, 1971; Flannery et al., 1996; and H. moschatus, Johnson and Strahan, 1982), and bipedal hopping characterized by synchronous use of the hind limbs only (used at high speeds by 2. Evolution of Hind Limb Proportions in Kangaroos (Marsupialia: Macropodoidea)