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| Habitat reconstruction of Riversleigh’s Middle Miocene forests including Malleodectes mirabilis (bottom right), M. wentworthi (top left), Malleodectes arenai (top right) and Weirdodectes napoleoni (bottom left). Churchill, Archer & Hand, 2025 Illustration by Nellie Pease. |
Abstract
Isolated upper teeth of a new fourth species of Malleodectes, M. arenai sp. nov. and an isolated lower molar representing a new genus of diminutive malleodectid, Weirdodectes napoleoni sp. nov. are described from Riversleigh’s Middle Miocene deposits. In addition, new malleodectid dental material from Middle and Late Miocene deposits at Riversleigh includes the first lower dentition of Malleodectes mirabilis and the first upper dentition of M. wentworthi. Comparisons of the upper and lower dentitions of M. mirabilis and M. wentworthi with that of the putative dasyurid Barinya wangala suggests that taxon is also a malleodectid. Parsimony and Bayesian phylogenetic analyses support a congeneric relationship between M. mirabilis and M. wentworthi, and support assignment of species of Barinya to Malleodectidae. These analyses support previous studies that found malleodectids were more closely related to dasyurids and myrmecobiids than to thylacinids. The snail-eating hypothesis for malleodectids is restricted to species of Malleodectes, with a more generalised durophagous diet suggested for B. wangala. The diet of Weirdodectes napoleoni sp. nov. is unknown but its dentition suggests it was highly specialised.
Keywords: Dasyuromorphia, Malleodectidae, Riversleigh, Taxonomy, Phylogenetics
MAMMALIA Linnaeus, 1758
MARSUPIALIA Illiger, 1811 sensu Beck et al. (2014)
DASYUROMORPHIA Gill, 1872 sensu Kealy and Beck (2017)
†MALLEODECTIDAE Archer et al., 2016
Type species: Malleodectes mirabilis Arena et al., 2011.
MALLEODECTINAE subfamily novum
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| Head reconstructions and silhouettes of Malleodectes mirabilis and M. wentworthi. Illustrations by Nellie Pease |
†Malleodectes arenai sp. nov.
Etymology: The species name arenai honours Dr Rick Arena for his contributions to palaeontological and geological research at Riversleigh including description of the genus Malleodectes.
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| Weirdodectes napoleoni sp. nov. holotype left m1 (QM F61732) microCT images. a. lingual view; b. buccal view; c. oblique buccal view; ... i. posterior view. |
?MALLEODECTIDAE Archer et al., 2016
Subfamily incertae sedis
†WEIRDODECTES gen. nov.
Etymology: The genus name, Weirdodectes, describes the bizarre and highly specialised m1 crown morphology of this taxon which is unlike any other marsupial carnivore currently known.
†Weirdodectes napoleoni sp. nov.
Etymology: The species name, napoleoni, honours the late Napoleon, the Great Pyrenees Mountain dog who provided unwavering emotional support throughout my undergraduate, honours and PhD years. You will be missed my loyal and magnificent friend, but never forgotten.
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| Habitat reconstruction of Riversleigh’s Middle Miocene forests including Malleodectes mirabilis (bottom right), M. wentworthi (top left), M. arenai (top right) and Weirdodectes napoleoni (bottom left). Illustration by Nellie Pease. |
Timothy J. Churchill, Michael Archer and Suzanne J. Hand. 2025. A New Genus and Two New Species of malleodectid (Marsupialia, Malleodectidae) from the Middle and Late Miocene Deposits of the Riversleigh World Heritage Area, northwestern Queensland. Journal of Mammalian Evolution. 32, 16. DOI: doi.org/10.1007/s10914-025-09755-6
