Malleodectes

Malleodectes is a genus of unusual marsupial species, first discovered in 2011 at Riversleigh, Queensland, Australia.[2] It could grow as large as a ferret, and lived in the Miocene, 17 million years ago. The reason for its name, which means "Hammer Biter", is because it has blunt, hammer like teeth, not known from any other mammal extant or extinct. However, Scott Hocknull from the Queensland Museum has noticed similarities to the modern pink-tongued skink (Cyclodomorphus gerrardii), a reptile specialised for eating snails.[3] This suggests that Malleodectes too was a specialised snail hunter.

Malleodectes
Temporal range: Middle Miocene–Late Miocene
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Marsupialia
Order: Dasyuromorphia
Family: †Malleodectidae
Archer et al., 2016
Genus: †Malleodectes
Arena et al., 2011 [1]
Type species
Malleodectes mirabilis

Taxonomy

The description of new taxa, genus and two species, was published in 2011, based on fossilised type material discovered at a Riversleigh site. The type species is named Malleodectes mirabilis and the second description published as Malleodectes moenia; their generic epithet combines terms derived from the Latin, malleo meaning hammer, and Ancient Greek, dectes for biter, in reference to the unusual dentition.

Malleodectes was reclassified as the sole genus of Malleodectidae in a 2016 revision, with the family allied to Dasyuromorphia.[4]

The arrangement published in 2016 may be summarised as,

  • Family Malleodectidae
  • Genus Malleodectes
  • Species Malleodectes mirabilis
  • Species Malleodectes moenia

A fossil species of opossum uncovered in excavations in Brazil has been proposed as a sister taxon to the genus, and that its genus Gaylordia could be placed with the same family.[5]

Description

A marsupial with highly specialised dentition, an enlarged premolar with a flattened profile used to hammer open the shells of snails found in its wet forested environment. This tooth was compared by the authors to a genus of skinks, Cyclodomorphus, and concluded this represented evolutionary convergence with the modern skinks that have similar adaptation to their diet of snails; the authors gave a generalised description of this unusual animal as a "marsupial-skink".[1][6]

A leading author on the research and description of the species, professor Michael Archer, said of the type species, "Malleodectes mirabilis was a bizarre mammal, as strange in its own way as a koala or kangaroo …,".[2] Fossil material associated with genus had been collected by workers at Riversleigh in the years leading to the crucial discovery of a juvenile jaw containing unerupted adult teeth. The juvenile specimen was found at a cave floor deposit with the remains of other animals, the AL90 site, and postulated to have fallen from its mother into a cave that once existed in the limestone formation.[6]

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References
  1. Derrick A. Arena; Michael Archer; Henk Godthelp; Suzanne J. Hand; Scott Hocknull (2011). "Hammer-toothed 'marsupial skinks' from the Australian Cenozoic". Proceedings of the Royal Society B. 278 (1724): 3529–3533. doi:10.1098/rspb.2011.0486. PMC 3189376. PMID 21508033.
  2. "Experts unearth ancient snail-eating marsupial". ABC News. 21 April 2011. Retrieved 27 April 2011.
  3. Viegas, Jennifer (20 April 2011). "'Hammer-biter' mammal built for eating crunchy food". Discovery News. Retrieved 27 April 2011.
  4. Archer, M.; Hand, S. J.; Black, K. H.; Beck, R. M. D.; Arena, D. A.; Wilson, L. A. B.; Kealy, S.; Hung, T.-t. (2016-05-27). "A new family of bizarre durophagous carnivorous marsupials from Miocene deposits in the Riversleigh World Heritage Area, northwestern Queensland". Scientific Reports. 6: 26911. doi:10.1038/srep26911. ISSN 2045-2322. PMC 4882580. PMID 27229325.
  5. "Gaylordia Paula Couto 1952". fossilworks.org. Retrieved 20 May 2019.
  6. Smith, D. (27 May 2016). "Researchers find remains of bizarre group of extinct snail-eating marsupials". UNSW Newsroom. University of New South Wales.
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