New Zealand's First Land Mammal Discovered

Bob Beale writes to clue us to big news from New Zealand. The country has long been thought to have been devoid of land mammals until recent times. No mammal fossils had ever been found there; but now one has. From the article: "Small but remarkable fossils found in New Zealand will prompt a major rewrite of prehistory textbooks, showing for the first time that the so-called 'land of birds' was once home to mammals as well. The tiny fossilized bones — part of a jaw and hip — belonged to a unique, mouse-sized land animal unlike any other mammal known... The fact that even one land mammal had lived there, at least 16 million years ago, has put paid to the theory that New Zealand's rich bird fauna had evolved there because they had no competition from land mammals."

Comments

well

[jrwr00]

I think maybe that fossil was carried over when the birds where hunting off the island

Re:well

[awing0]

What, held under the dorsal guiding feathers?

Re:well

[Rob the Bold]

maybe as thier shit, thats what i was mostly going by

That sound you heard going over your head was an African Swallow.

Re:well

[Vreejack]

Maybe two birds could have carried it together, using a vine.

Re:well

[damien_kane]

It might have been two European swallows...

I disagree

[joe 155]

"has put paid to the theory that New Zealand's rich bird fauna had evolved there because they had no competition from land mammals"

I don't really see how... one small mouse, even if there was 1 million of them, wouldn't really have made much difference to birds; it'd only be preditors that made a big difference

Re:I disagree

[Tmack]

"has put paid to the theory that New Zealand's rich bird fauna had evolved there because they had no competition from land mammals"

I don't really see how... one small mouse, even if there was 1 million of them, wouldn't really have made much difference to birds; it'd only be preditors that made a big difference

They would make a difference... as food

tm

Re:I disagree

[TheNicestGuy]

Another huge difference mammal competition can make to bird evolution is the fact that there have always been a lot of wily egg-eating mammals.

Re:I disagree

[camperdave]

Well, a few pigs killed off the dodo by eating its eggs. Millions of small rodents could put a significant dent in an ecosystem if they took a liking to bird eggs. And that's only a direct example. They could conceivably out-compete certain birds for seeds. They could be a perfect breeding ground for parasites. They could be lunch for the birds. Their rotting carcases could increase the fly populations, thus indirectly providing more food to the birds. There's dozens of ways that millions of mice could alter an ecosystem.

Re:I disagree

[CrimsonAvenger]

It's not that far from mainland Oz to have eaten dinner in Oz and then head home with some mouse constipation.

Umm, New Zealand is about 1000 miles from Australia last time I checked.

Hardly a short flight for anything but an albatross.

Re:I disagree

[Artifakt]

Scientists tend to reject remote chances near automatically when it comes to fossils. Since only about 1 creature in 100 million or so ever gets found in fossil form (addmitedly a rough average), the odds of that also being a 1 in 100 million exception for other reasons become very much astronomical (or even just a one in a million chance does). If we have only 6 Foobarasaurus Smex fossils that are close enough to full skeletons to judge size well, and there were probably 600 million of them during the whole time the species was around, what are the odds that one of those six is the biggest single specimen that ever lived? In the same way, what are the odds that one of those six died from being struck by lightning?

Re:I disagree

[matt_morgan]

Even very small mammals may eat the eggs of very large birds. In fact they often do.

The real issue here is that every species fills a niche. A mammal filling a niche means there will be no bird filling that niche. Nonetheless, it's kind of a dumb comment (not yours--I mean the original one you're referring to); one mammal species 16 mya will have less impact on bird evolution than many mammal species existing throughout time. 16 my is a lot of time for evolutionary changes to take place.

Mammals?! Oh, my...

[__aaclcg7560]

I thought New Zealand only had hobbits and Peter Jackson.

Re:Mammals?! Oh, my...

[__aaclcg7560]

My mistake. I meant that he was the One Hobbit to rule all Hobbits.

Re:Mammals?! Oh, my...

[Chris Burke]

... and in the franchise bind them?

Re:Mammals?! Oh, my...

[BLACKtactx]

Oh dear, when will the rest of the world learn that NZ Sheep jokes are neither original, funny, nor based on any implied "cultural" activity!!!!. In the words of the Lonely Planet Blue List Guide of 2005 - "dont mention sheep jokes, they have heard them all before".

modify the theory

[Johnny5000]

The fact that even one land mammal had lived there, at least 16 million years ago, has put paid to the theory that New Zealand's rich bird fauna had evolved there because they had no competition from land mammals."

OK, that theory is total crap now.
Here's the new theory:

New Zealand's rich bird fauna had evolved there because they had only a little bit of competition from one tiny land mammal.

Re:modify the theory

[mr_mischief]

One possibility is that this thing and all like it were already as dead as it is now. It's difficult for your offspring to evolve if you don't survive long enough to produce offspring.

Re:modify the theory

[florist]

So we go from "harmless" to "mostly harmless"?

Corrected theory statement

[smbarbour]

Only a small change required to the theory:

New Zealand's rich bird fauna had evolved there because they had little competition from land mammals.

One theory posits that ancient Australia...

[Anonymous Coward]

...established New Zealand as a colony for its most criminal mammals.

I suspect these are the bones of a dirty, little rat.

Re:One theory posits that ancient Australia...

[vaughanf]

No, no, no, you have it all wrong, Australia was the penal colony.

That's why we New Zealanders have so much respect for Australians.

Their ancestors have stood before some of the most prestigious judges in England!

On a related note, when going to Australia, there's a field on the form you fill in before entry asking if you have any criminal convictions. DON'T tell the customs people that you didn't realise it was still a requirement. They somehow fail to see the funny side.

Food for the birds?

[jmagar.com]

judging by the size, then perhaps this mammal was not competition, but instead a source of food for the birds...

I'd suggest a minor change to the theory instead of chucking the whole thing.

Re: Birds hunting off-shore

[TheNicestGuy]

Not likely. The article is placing this fossil around 16 mya (million years ago), while New Zealand was as isolated from all other landmasses as it is today by 60 mya at the latest. Unless that hunting bird had a range as wide as the Tasman Sea (about 2,000 km), it couldn't have gone off-shore to get mammals.

Yeah, right, because mice never eat eggs

[spun]

Mice also never eat any kind of insects or seeds that birds eat. In fact, mice and birds have never and will never compete for resources. Long live the mighty mouse/bird alliance!

Well, It Certainly Impacts the Theory

[eldavojohn]

I don't really see how... one small mouse, even if there was 1 million of them, wouldn't really have made much difference to birds; it'd only be preditors that made a big difference

Well, I think the overall logic is that this ancient mouse and its affiliates would most likely have prospered in New Zealand and eventually evolved into something that fed on birds. In a lot of places, mammals have been more successful than birds. Now, there are a few like places Antarctica where birds are probably more successful than mammals but New Zealand and its surrounding islands (like the Dodo on Mauritius) were pretty special in this respect. So special, that (as I learned in Jared Diamond's "Guns, Germs & Steel") when humans arrived, many of the bird species had no fear of humans--only curiosity. They didn't have the thousands of years of living side by side with humans like elephants & zebras did in Africa to slowly train them to stay away at all costs. So its evident they never lived with predators but why were mice fossils found and not other mammals?

So now we need to explain that the mouse and other mammals were either restricted by food sources or eliminated. It also has to explain why there aren't more mammals. What is it about New Zealand? Did a volcano periodically remove all life from the island so that only birds could repopulate it at some point? Perhaps the only mammals that survived a food shortage were mice which were subsequently overhunted by the birds? These are the new questions that now must be answered.

So we're still left with this question of why these 1 million mice didn't evolve or why their bird eating relatives didn't thrive on the island. I heavily endorse and suggest Guns, Germs & Steel if you haven't had the time to read it. It asks questions about subjects like these that for a long time people just used the creation theories to explain. Now we're finally starting to look for answers as to why the way things are the way they are and why some populations of humans are better off or have more 'cargo' than others.

Re:Well, It Certainly Impacts the Theory

[jd]

The birds in New Zealand are curious creatures. From the extinct Moa and Haast Eagle (both absolute giants) to the Kea, Kakapo and Kiwi, the birds in New Zealand have no characteristics that indicate ground-based predators. Your car is far more likely to be ripped to shreds by a psychotic flightless parrot than it is to be damaged in an accident with another vehicle. Fear? Those creatures show no fear! (In fact, their total reckless abandon probably drove the poor mouse out of its mind - I think it went extinct from the cost of psychiatric treatment.)

Re:Well, It Certainly Impacts the Theory

[natedubbya]

"So now we need to explain..."

That's why I love reading evolution "research" papers. They explain and explain, and then something happens to show it doesn't work, so they come up with a completely different explanation, etc. etc. I mean, come on, how hand wavy can you get and still call it valid science?

And no, I'm not anti-evolution (and no, not creationist, I'm just open to criticizing my own thoughts). I just enjoy how overly-serious people treat evolution theories, based on basically no evidence. Now we found a mouse! Ok, new theory! Bow to me!

Full article available via PNAS as 'open access'

[Buran]

I work at a major medical school in the U.S., and so the first thing I did when I read the linked article (I know, I know, GASP!) was find out what journal this was published in -- we have online subscriptions to hundreds of journals, so surely I could go to the primary source. PNAS considers this important enough that it has the article tagged as "open access" -- free for all to read.

Miocene mammal reveals a Mesozoic ghost lineage on insular New Zealand, southwest Pacific -- Worthy et al., 10.1073/pnas.0605684103 -- Proceedings of the National Academy of Sciences

The abstract is standard HTML, but the full article is in PDF format (link to the full article PDF).

Citation:

Worthy, T. H., A. J. Tennyson, M. Archer, A. M. Musser, S. J. Hand, C. Jones, B. J. Douglas, J. A. McNamara and R. M. Beck (2006). Miocene mammal reveals a Mesozoic ghost lineage on insular New Zealand, southwest Pacific. Proc Natl Acad Sci U S A.

(no volume or page numbers as this article has not yet been published in print).

Bats

[Mercedes308]

New Zealand has two species of native bats, would they count as mammals?

Re:Bats

[Conanymous Award]

Bats do, of course, count as mammals, but we are speaking ground-dwelling mammals here. New Zealand supposedly never had those before the human invasion. No we know they had, once.

Still, I don't see this that hard a fact to reconcile with the traditional view of NZ as a Kingdom of Birds. The animal was still only a small critter. Sure, critters as small as rats are known to have exterminated ground-dwelling bird species from isolated island ecosystems. But NZ is much bigger than Hawaii, Mauritius, Galápagos and other famous examples of island extinction. This would mean its bird-dominated ecosystems and bird species would have been much more robust and resistant to a mammalian threat. Why, there were large, flightless predatory birds on the island continent of South Africa before the Great American Interchange. And how about the ostrich, emu & co.?

This new fossil mammal also appears to represent a very ancient lineage dating back to early Cretaceous mammals. We know for fact these critters were not necessarily some übermammal bird-pwners: after the KT extinction (the one that killed the dinosaurs, y'know), for a short while birds were among the top predators, and there were many other flightless birds, too, all over the world. This seems to indicate that early mammals were not the bird menace modern placental mammals like rats, pigs, and cats (and us) are. Nothing mysterious going on here, methinks. You simply cannot compare an advanced Neogene placental to a primitive Cretaceous type of proto-shrew in terms of predatory efficiency.

And how about this possibility: NZ only became a bird paradise after this critter and its relatives went the way of the dodo, for some reason or another?

Interesting. (Obligatory eyebrow raise.)

[M0b1u5]

Interesting.

The fact we have native mammals (bats) in NZ hasn't really been discussed yet. How does that fit in with the observation of a mouse-sized land mammal 16 million years ago?

I find it annoyingly hard to reconcile, as we know that "Life will find a way" - and historically, land mammals have been particularly agressive in their expansion into new habitats, even going back to the sea (Ambulocetus) and taking on the birds (Bats et al).

Someone suggested volcanic activity - but this only applies to the North Island and the top of the South Island. The Taupo "eruption" og 86AD was reported by the chinese and the romans at the time. More than 30 cubic kilometres of matter was ejected in as little as 7 minutes.

However, this is dwarfed by the explosion 20,000 years ago, where over 2,000 cubic kilometres were ejected, as the magma chamber below Lake Taupo collapsed. The ferocity of this event is simply too large to imagine, and the landscape of the North Island was almost totally covered in ignumbrite, a gassy, fast flowing lava, expanding our from the crater at close to the speed of sound, in a wall some 200-300 metres tall...

The resulting Rhyolite domes from previosu explosions were actually topped by the outflow.

However, even as close as 5 kilomtres from the vent, some plant and animal life survived, and as the trillions of litres of water held loosely by the ignumbrite ran swiftly back to the lake area, and the remains of the North Island forests burned in one of the greatest fires in pre-history, and the rock cracked and cooled under muddy rain, the animals, birds, and plants made their way back into the landscape.

So - no - Taupo couldn't wipe out the land mammals of New Zealand, and the South of the South Island is almost entirely devoid of volcanos: Dunedin and Lyttleton volcanos were small, and not very violent in terms of the entire island.

There is an alternative available. The "Pukeko" is a common bird in New Zealand, and they are very poor flyers - certainly not capable of flying from Australia, where they evolved (They are the Australian "Swamp Hen") and yet they florish in New Zealand. They have only been here for a few thousand years. The best theory is that they came across on flotsam ejected from rivers during large storm events in Australia.

If Pukeko cxan arrive that way, then small mammals might also survive to arrive in New Zealand, but the number who arrived might not have been sufficient to maintain a good breeding pool, so the species might go extinct due to the lack of genetic diversity.

This would explain the discovery, the lack of other land mammals and the lack of fossils: if there were bugger all who ever floated over, then we are spectacularly lucky to even have found these ones.

That's my story anyway.

Re:Interesting. (Obligatory eyebrow raise.)

[mudshark]

Pukeko are hell on mice, or anything that will fit in their beaks for that matter. They're quite effective hunters, as anyone who has free-roaming poultry in rural NZ will attest. So maybe that's where the little furry buggers went.

Re: Birds hunting off-shore

[jd]

The Haast Eagle (the largest eagle that ever lived, the largest bird capable of flight and the largest an animal could physically get and still lift itself on wings) might well have had a range of 2,000 Km. If reports of giant eagles of similar size in other countries are to be believed, then it must have had the range as they certainly never evolved anywhere else.