Evolution and systematics

The order Dasyuromorphia includes three families of carnivorous marsupials in the superfamily Dasyuroidea: the Dasyuridae (dasyures), the Myrmecobiidae (numbat), and the Thylacinidae (thylacines). The dasyurids and thylacinids are more closely related to each other than they are to the num-bat. The Australian marsupial radiation produced a number of other species of carnivorous marsupials in the otherwise herbivorous order Diprotodontia. These include two genera (Thylacoleo and Wakaleo) and seven species of large, up to 220 lb (100 kg), predatory marsupial lions of the family Thyla-coleonidae, which are most closely related to koalas and wombats (superfamily Vombatoidea), and an omnivorous (partly flesh-eating) giant rat-kangaroo, in the subfamily Pro-pleopinae, family Hypsiprymnodontidae, superfamily Macrop-odoidea.

The earliest known carnivorous marsupial in Australia, Djarthia murgonensis, comes from the early Eocene (55 million years ago [mya]). The taxonomic affiliation of this and two other early carnivorous marsupials is not certain, as key anatomical features used to clearly identify them to family level or even to separate them from the South American marsupial fauna are lacking in the fossils found to date. The Australian dasyuromorphian and American marsupial taxa are quite distinct but are allied in the possession of many incisors

(polyprotodonty) which distinguish them from the herbivorous Diprotodontia. Dasyuromorphians originated in the late Oligocene. The early radiation comprised the very conservative or "primitive" thylacinids. Ranging in size from small dog-sized, 70.5-176.4 oz (2-5 kg) to slightly larger than 65 lb (30 kg), thylacines dominated the Australian carnivorous marsupial fauna until the late Miocene, after which they steadily declined to two species present in the Pleistocene and only one persisting until historic times. Dasyurids first appeared in the fossil record in the early to middle Miocene but were rare until the late Miocene when they diversified and replaced the thylacine as the dominant marsupial carnivore fauna. Most of the Pleistocene fossil dasyurids are from still-living taxa, although none of the living groups occur earlier than the Pliocene. Dasyurids are considered to be highly specialized or "derived" dasyuromorphians in terms of their morphology. The numbats are represented by only one living species which appeared in the fossil record as recently as the Pleistocene. The numbat is a highly specialised dasyuromor-phian, with features of the skull, teeth, and tongue adapted for termite feeding.

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