New discoveries on marsupials of Australia and South America


This video is about the Monito del monte (Dromiciops gliroides).

From the University of New South Wales in Australia:

Tiny marsupial is ‘living fossil’

Wednesday, 26 March 2008

The Monito del Monte (Dromiciops australis) may have originated from Australia’s oldest marsupial and then made the return trip to South America.

They are separated by a vast ocean and by millions of years, but tiny prehistoric bones found on a Queensland farm have been directly linked to a strange and secretive little animal that lives today in the southern rainforests of South America.

The fossilised ankle and ear bones are those of Australia’s earliest known marsupial, Djarthia, a primitive mouse-like creature that lived 55 million years ago. It is a kind of Australian Eve, possibly the mother of all the continent’s unusual pouched mammals, such as kangaroos, koalas, possums and wombats.

But a study in the journal PLoS ONE has confirmed that Djarthia is also a primitive relative of the small marsupial known as the Monito del Monte – or “little mountain monkey” – from the dense humid forests of Chile and Argentina.

Although scientists now generally agree that marsupials found their way to Australia from South America, the new finding suggests that the Monito del Monte may subsequently have made the return journey and is indeed a living fossil, the last of a lineage that can be traced back to Djarthia.

The bones were collected from the Tingamarra fossil site near Murgon, in Queensland, and have been studied by a research team led by Mr Robin Beck, a doctoral student in palaeontology at the University of New South Wales, in Sydney.

“It’s now accepted that Australia’s marsupials are the result of dispersal from South America via Antarctica, when the three continents were joined as part of the super-continent Gondwana,” Mr Beck says.

“We know from other fossils that marsupials were present in South America at least five million years before Djarthia, which is by far Australia’s oldest and most primitive marsupial fossil.

“Scientists already suspected that the Monito del Monte is more closely related to Australia’s marsupials than to South America’s, but its exact origins have been controversial. Until now, we only knew Djarthia from isolated teeth, which weren’t enough to tell us whether it was related to the Monito del Monte or not.”

“The fossil ankle and ear bones of Djarthia make it clear that the Monito del Monte descends from a Djarthia-like ancestor, and so probably returned to South America from Australia before Gondwana broke up. The continents have been separated by deep ocean since about 40 million years ago.”

Like the Monito del Monte, Djarthia was a little larger than a mouse and, likewise, its ankle bones show adaptations for climbing trees. It probably had a similar diet as well: the Monito del Monte eats insects and other small invertebrates and some fruits.

The Monito del Monte is nocturnal and its agility and prehensile tail make it an excellent climber. Females carry up to five young in a well-developed pouch.

Sparassodonta — Extinct Sabretoothed Marsupials: here.

4 thoughts on “New discoveries on marsupials of Australia and South America

  1. Sabre-toothed ‘bear’ terrorised early humans

    * 05 May 2008
    * Emma Young
    * Magazine issue 2654

    A sabre-toothed cat that sported the fearsome teeth of felines also had the body and gait of a bear, making it a “super-predator”.

    So says a team led by Stephen Wroe at the University of New South Wales, Sydney, Australia, which found that the ferocious marsupial lion (Thylacoleo carnifex) shared the same super-predator body plan as Smilodon fatalis, North America’s ice age sabre-tooth cat.

    Wroe and his team compared the skulls, teeth and body proportions of seven extinct mammalian predators with those of 22 living species, in a bid to better understand how the extinct animals behaved.

    They found that five of the extinct species fell reasonably neatly into known predator groups. Two sabre-toothed cats sit well with modern- day felines, for instance, leading the team to conclude that they probably occupied a similar ecological niche. Smilodon and Thylacoleo didn’t fit into any group but they did have a lot …

    The complete article is 472 words long.

    http://www.newscientist.com/channel/life/mg19826544.400-sabretoothed-bear-terrorised-early-humans.html?feedId=life_rss20

    Like

  2. Pingback: Giant fossil mammal discovered in Australia | Dear Kitty. Some blog

  3. Pingback: Fossil marsupials discovery in Bolivia | Dear Kitty. Some blog

  4. Pingback: South American marsupials climb higher than thought | Dear Kitty. Some blog

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