Posted on 03/26/2008 1:49:15 PM PDT by blam
Primitive Mouse-Like Creature May Be Ancestral Mother Of Australia's Unusual Pouched Mammals
The Monito del Monte (Dromiciops gliroides) (Credit: Image courtesy of University of New South Wales)
ScienceDaily (Mar. 26, 2008) — They are separated by a vast ocean and by millions of years, but tiny prehistoric bones found on an Australian 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 new study 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.
Journal reference: Beck RMD, Godthelp H, Weisbecker V, Archer M, Hand SJ (2008) Australia's Oldest Marsupial Fossils and their Biogeographical Implications. PLoS One 3(3): e1858. doi:10.1371/journal.pone.0001858
Adapted from materials provided by University of New South Wales.
Cool! (Cute too.)
I’ll venture a guess they taste like chicken.
OR - - - God could have created each animal after its own kind.
Noah had to draw the line on anything bigger than elephants,
so that’s why we don’t have any of those honking dinosauers.
Likewise, scientists should be on the lookout during their research for primitive Rat-Like Creatures, as they may be ancestral mother's of today's modern DemocRats.
Like the Monito del Monte, Djarthia was a little larger than a mouse
How do find the fossilized ear bones of creature the size of mouse?
Bones that size would hardly be large than the grains of sand you would be sifting through.
Whatever “kind” means in reality.
I’ve watched a guy at a well-known natural history museum working on the extraction of a tiny jawbone from a piece of rock under a microscope. Not work for the easily bored or distracted (or the hard of seeing), let me tell you!
Of course. But please define kind.
Q. What's harder than getting a pregnant Brontosaurus into the ark?A. Getting a Brontosaurus pregnant in the ark!
(Noah! Make them stop. I'm getting seasick!)
Not to mention a steady hand.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.