First fossil mammal found in New Zealand

This video from the USA says about itself:

Oct 15, 2008

On the Science Channel‘s “Mammals vs. Dinos,” paleontologist Adrian Hunt discovered Adelobasileus, the oldest known mammalian fossil in the Chinle Formation. Adelobasileus is thought to be the common ancestor of mammals and lived 200 million years ago.

From the Australian Broadcasting Corporation:

Ancient Kiwi ‘mouse’ fills fossil gap

Marilyn Head

ABC Science Online

Tuesday, 12 December 2006

Palaeontologists have found remains of one of the most primitive type of land mammal in the world, a mouse-sized creature that’s unlike any mammal alive today.

The find, at the edge of a swampy lake on New Zealand’s South Island, not only fills a gap of the nation’s fossil record, it may also help us understand more about the origin of mammals worldwide.

Researchers, led by Trevor Worthy from Australia’s University of Adelaide, publish their results today online in the Proceedings of the National Academy of Sciences.

Many types of mammals evolved in the Mesozoic period when the dinosaurs dominated, says co-author Alan Tennyson, a palaeontologist from the Museum of New Zealand Te Papa Tongarewa.

But most of those early lineages are now extinct and mammals living today fall into only one of three groups: placentals, marsupials or monotremes.

But this latest find, in sediments deposited 16-19 million years ago, doesn’t fit into any of these groups.

“This is an incredible find. We never expected to find anything like this,” says Tennyson.

“What’s so exciting about this fossil mammal is that it is from one of those ancient lineages that we thought had become extinct much earlier.

This will help us understand more about the origin of mammals worldwide,” he says.

The find is particularly significant for New Zealand as there are virtually no fossils of terrestrial vertebrates between 65 million years ago, when an asteroid impact is thought to have wiped out the dinosaurs, and about 1 million years ago.

In other parts of the world many different mammals evolved to replace dinosaurs as the dominant species.

But in New Zealand the only terrestrial vertebrates that seemed to have evolved were reptiles, frogs, and birds – not mammals.

That’s despite the fact that New Zealand’s landmass separated from Gondwana after many mammals had evolved.

“The suggestion has been that giant birds, like the extinct Haast eagle and the moa, filled the ecological niches that mammals like tigers and grazing animals did elsewhere,” says Tennyson.

“But this is a very primitive mammal and it’s unlikely to have lived here for 60 million years without diversification.

So it opens the possibility that there may be bigger mammals to be found.”

The researchers say the discovery implies the existence of one or more ‘ghost lineages’ and suggests that mammals may have existed on New Zealand more than 125 million years ago.

That may contradict an alternative theory for the lack of fossil evidence for terrestrial mammals: that New Zealand was completely submerged about 25 million years ago and that all of its animals and plants arrived from nearby landmasses.

But the paper suggests that the discovery, along with other Mesozoic survivors such as the lizard-like tuatara and New Zealand’s primitive frogs, confirms that at least some land remained above water throughout the period.

See also here.

Kiwi on New Zealand Stewart island: here.

The recently described St Bathans Fauna, from the Manuherikia Group, Early–Middle Miocene, 19–16 Ma, New Zealand, includes six anatid taxa: here.

Australia: digging for dinosaurs and dinosaur age spiny anteater relatives: here.

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