Metatheria: Marsupial Mammals• First fossils are from Asia (Lauraisa) ~ 125 MYA.• Complex biogeography, related to the formation and rupture

of Gondwanaland

Hypothesized Single Dispersal to Australia

Metatheria: Marsupial Mammals

Single Dispersal Hypothesis

Supported by phylogenies of extant taxa:(Nilsson et. al, 2010. PLoS Biology)

Challenged by phylogenies with fossil taxa:(Beck 2012. Naturwissenschaften)

Order Didelphimorphia, Family DidelphidaeDidelphis - American opossum

Order Didelphimorphia, Family Didelphidae

Marmosa: mouse opossums

Monodelphis:short-tailed opossums

Order Paucituberculata, Family CaenolestidaeCaenolestes - shrew opossums

Order Microbiotheria, Family MicrobiotheriidaeDromiciops – Monito del monte

Australian Groups

Order Notoryctemorphia, Family NotoryctidaeNotoryctes - marsupial mole

Fossorial Adaptations Small eyes and small pinnae Fur is velvety – doesn’t lie in one direction Fusiform body with a short tail

Forelimbs modified for digging

Order Dasyuromorphia, Family Dasyuridae

Sarcophilus - Tasmanian devil

Antechinus – Marsupial mouse

Order Dasyuromorphia, Family ThylacinidaeThylacinus cynocephalus - Tasmanian wolf

Order Dasyuromorphia, Family MyrmecobiidaeMyrmecobius - numbat

Myrmecophagus adaptations:Long rostrum Long, protrusible tongueDelicate dentary Copious, sticky salivaTeeth reduced/absent Forelimbs modified for digging

Order Peramelemorphia, Family PeramelidaeMacrotis - rabbit-eared bandicoot (bilby)

Syndactylous - one sheath of skin for >1 digit (2nd & 3rd).

Order Diprotodontia

Largest order: 10 Families

Most forms have just two lower incisors.

Many forms are syndactylous.

Order Diprotodontia, Family PhalangeridaeTrichosurus vulpecula – Common brush-tailed possum

Order Diprotodontia, Family PetauridaePetaurus breviceps - sugar glider

Order Diprotodontia, Family PhascolarctidaePhascolarctus cinereus - koala

2nd & 3rd digits syndactylous

Order Diprotodontia, Family PhascolarctidaePhascolarctus cinereus - koala

- Our first example of an arboreal foliavorelow quality foodeat almost constantly while awakesleep to digestlow metabolism heterothermicdense fur to retain body heat

Order Diprotodontia, Family VombatidaeLasiorhinus - hairy-nosed wombat

Order Diprotodontia, Family MacropodidaeMacropus rufus - red kangaroo

Extreme adaptations for saltation (bipedal hopping)

Order Diprotodontia, Family MacropodidaeDendrolagus - tree kangaroo

Order Diprotodontia, Family MacropodidaePetrogale - rock wallaby