A new family of bizarre durophagous carnivorous marsupials from Miocene deposits in the Riversleigh World Heritage Area, northwestern Queensland

Abstract

A new specimen of the bizarrely specialised Malleodectes mirabilis from middle Miocene deposits in the Riversleigh World Heritage Area provides the first and only information about the molar dentition of this strange group of extinct marsupials. Apart from striking autapomorphies such as the enormous P3, other dental features such as stylar cusp D being larger than B suggest it belongs in the Order Dasyuromorphia. Phylogenetic analysis of 62 craniodental characters places Malleodectes within Dasyuromorphia albeit with weak support and without indication of specific relationships to any of the three established families (Dasyuridae, Myrmecobiidae and Thylacinidae). Accordingly we have allocated Malleodectes to the new family, Malleodectidae. Some features suggest potential links to previously named dasyuromorphians from Riversleigh (e.g., Ganbulanyi) but these are too poorly known to test this possibility. Although the original interpretation of a steeply declining molar row in Malleodectes can be rejected, it continues to seem likely that malleodectids specialised on snails but probably also consumed a wider range of prey items including small vertebrates. Whatever their actual diet, malleodectids appear to have filled a niche in Australia’s rainforests that has not been occupied by any other mammal group anywhere in the world from the Miocene onwards.

Systematic affinities of the extinct metatherian Eobrasilia coutoi Simpson, 1947, a South American Early Eocene Stagodontidae: implications for "Eobrasiliinae"

“…Malleodectes represents an independent evolutionary event of its lineage in Australia, not directly linked to any South American taxa, including Gaylordia. This conclusion is supported by Archer et al (2016), who described new materials assigned to this taxon, grouping it in the family Malleodectidae, within Dasyuromorpha Gill, 1872.…”

“…Malleodectes mirabilis Arena et al, 2011, presents a reduced P1 comparing to P2-3 as in referred South and North American taxa (Arena et al, 2011;Archer et al, 2016). Nevertheless, the pattern of its upper premolars is divergent from the one present in American taxa.…”

“…The presence of this pattern is an evidence for durophagous habits among these taxa (Fox & Naylor, 2006;Arena et al, 2011;Scott & Fox, 2015;Archer et al, 2016). Aside from this resemblance, these teeth present diagnostic morphologies that represent independent acquisitions for them.…”

“…Nevertheless, the pattern of its upper premolars is divergent from the one present in American taxa. The P1 is two-rooted, poorly developed, but not as vestigial as in Stagodontidae, aligned with dental row axis and separated by a small retropremolar space from P2 (Arena et al, 2011;Archer et al, 2016) (Figure 6). Its morphology is more similar to Gaylordia.…”

A new species of Miocene wombat (Marsupialia, Vombatiformes) from Riversleigh, Queensland, Australia, and implications for the evolutionary history of the Vombatidae

“…This is not sur- Results of the phylogenetic analysis with additional species added (relative branching order of these additional taxa are shown here as not resolved) against the geological time scale (Gradstein et al, 2012). Age span of deposits containing all known wombat taxa are provided, with black bars indicating certainty (such as radiometrically dated sites) and grey indicating uncertainty (ages are based on Archer and Wade, 1976;Archer et al, 1989Archer et al, , 1997Archer et al, , 2016Arena et al, 2016;Beck, 2008;Beheregaray et al, 2000;Black et al, 2012b;Cupper and Duncan, 2006;Dawson, 1985;Hope and Wilkinson, 1982;Myers et al, 2001Myers et al, , 2017Piper et al, 2006;Pledge, 1992;Price et al, 2009Price et al, , 2011Prideaux et al, 2010;Vickers-Rich et al, 1991;Roberts et al, 2001;Stirton et al, 1967;Taylor et al, 1994;Tedford et al, 2006;Travouillon et al, 2006Travouillon et al, , 2011Whitelaw 1989Whitelaw , 1991Woodhead et al, 2014). Age of split between taxa is based on oldest possible deposits containing those taxa and as such will change as more information becomes available.…”