Just to annoy Meleah ....

[tyggerjai]

http://sfgate.com/cgi-bin/article.cgi?file=/c/a/2004/11/30/MNGVNA3PE11.DTL

And to provide some rational balance:
http://www.lasvegascitylife.com/articles/2004/11/24/opinion/all_tomorrows_parties/atp.txt

Hey, Leah, while we're on the topic, would I be right in saying that mainland Australia has no native cats, and that this goes a long way to explaining our over-endowment of native marsupials?

sol.
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Comments

[thorfinn]

Naah. The marsupial thing is just straight out due to us breaking off from Gondwanaland, IIRC. Evolution generally involves the whole ecological web, and for some reason, our evolutionary bush just happened to grow from the marsupial branch rather than the placental branch. Most of the same niches exist...

The trick is that we retained megafauna for a lot longer than elsewhere. They die out around the time the aboriginals arrive. Arguments as to whether it's climate change or just plain firebugging by humans are ongoing, I think, but leaning in the direction of human firebugging. But basically, whilst there's megafauna, the whole "small predator" niche (which the small cats fit into) doesn't really happen, because most of the prey animals are a little too big to be eaten by small predators.

meleah can probably give you a more accurate precis, but I think that's the basic story.

[sly-girl.livejournal.com]

The trick is that we retained megafauna for a lot longer than elsewhere.

I've always wandered about that. If you take the literal meaning of the word, then megafauna is really just big animals. If you ask me, then elephants and giraffes and rhinoceroses seem like pretty bloody big animals.

[thorfinn]

Err, yar. Forgot about Africa. :-) And the predators there are pretty damn big... They've got cats, but big ones.

[meleah.livejournal.com]

Er, I'm not sure that we retain megafauna for much longer than elsewhere (and yeah, Africa techinically, still got their megafauna, or so at least one argument goes).

But basically, whilst there's megafauna, the whole "small predator" niche (which the small cats fit into) doesn't really happen, because most of the prey animals are a little too big to be eaten by small predators.

That's a bit of an odd comment. Firstly, I didn't suppose Jai meant domestic-sized cats only - and Lions etc. are quite capable of taking down large prey. Secondly, there's a significant mammalian history on this continent prior to the megafauna, and so no reason we can't be looking at an ancient lineage - unless you'd argue that they died out when the megafauna was around because they had nothing to eat? thing is, not everything was huge during the megafauna's time of dominance either.. so there's plenty of smaller things around as well.

The existence of niches, just which ones were around, what was different here, etc. is a very interesting question right now, especially given prevailing wisdom that Australia didnt' have any signifcant carnivores is being challenged by work underway by a few people, re-inventing animals like the marsupial lion into rather more scary hyper-carnivores than they were previously thought to be..

[thorfinn]

I think I was relying on the "prevailing wisdom" of Australia lacking in carnivores... And presumably with megafauna around, whilst there would still be plenty of smaller herbivore animals, there'd be a whole lot less than if the entire herbivore base is small animals, resulting in no big niche for a small carnivore... And yeah... I thought Jai was implying small cats only, and responded on that basis. Even so, lions and such don't usually take down the megafauna, IIRC...

As for Australian carnivores... Hrm. It wouldn't be surprising if we did have marsupial carnivores, given the prevalence of marsupial herbivores. I guess that's been the point - we've been "unusual" in the lack of carnivores... It wouldn't at all surprise me if that lack turned out not to be a lack at all.

[meleah.livejournal.com]

Well we know we had marsupial carnivores.. that's not a question. We had a diverse array of thylacinids, we had the dasyurids (although they look to be mostly small prior to the decline of the thylcainids), and we had the thylacoleonids. The question is just whether we supported large hyper-carnivores, or whether the mammalian fauna was instead preyed upon by the reptiles, such as Megalania. The popular view for a long time has been that the Australian continent is relatively nutrient-poor, which allows only a certain amount of mammalian biomass. This, it is argued, would not be enough to sustain many high-metabolism carnivores (ie: mammalian) so instead, in the australian ecosystem, reptiles filled that role (Megalania, Baru, Quinkana, etc.). More recent work has disagreed with this, and re-examined the role of predators like Thylacoleo, originally dismissed as a scavenger or perhaps even a herbivore, despite obvious carnassial specialisation of the jaws and skull. Body weight ratios and so on are important to this argument however, and you'd be surprised how far behind we are on working out simple regressions for australian animals... debate rages as we speak.

[tyggerjai.livejournal.com]

IHNTA, IJLTS "hyper-carnivore"!

sol.
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[meleah.livejournal.com]

IHNTA, IJLTS

Uhh...suuure.

[tyggerjai.livejournal.com]

I Have Nothing To Add, I Just Like To Say "hyper-carnivore" !

sol.
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[tyggerjai.livejournal.com]

Super-mega-fauna-saurus hyper-carnivorous!


sol.
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[thorfinn]

Oh, and re the megafauna death timeline... No, you're right, I mis-remembered. We don't lose them later than elsewhere. In fact, ours die out earlier than the North American ones and suchlike... http://www.abc.net.au/science/features/megafauna/default.htm has more stuff, including the debate for "human caused" vs "environmental factors". Seems that there's more evidence to support the latter, although the former may be a contributing factor too...

[meleah.livejournal.com]

*sigh*

Thanks, I needed more mindless homicidal rage in my day.

But to the question of cats..

If by 'cats' you mean Felidae, then no, we don't have any native cats. As Thorfy stated, we have (we think, sorta, except out here on the perimeter..) only really marsupials in australia (excepting bats which come in at 50 Ma and rodents which come in about 5 Ma), and the Felidae are placentals. However, there are a group of animals that are commonly known as the 'native cats and mice' called the Dasyuridae. These are the sister-group to the Thylacinidae (tassie tiger was the last survivor of this family, it was much more diverse/numerous in the mid Tertiary, but it looks like the Dasyurids took over after that, leaving the single survivor driven extinct by humans) and one of the more diverse groups of Australian mammals. They are carnivores on many different levels, from the small insectivores such as the Kowari, Ningaui, Antechinus, Sminthopsis etc. (which mostly look like little mice and are oft mistaken for such and killed by silly humans - look for a furry base of the tail, if its got that, its probably native, so lay off!) up to the larger forms such as Sarcophilus (the Tassie devil), and Dasyurus malucatus, the quoll or 'native cat'. They are often endangered, suffering both from habitat fragmentation and niche competition with introduced cats, foxes, etc. but were once quite widespread.

Over-endowment of native marsupials well.. not really. Marsupials are just a different class of mammals, and it looks like they just got a chance to diversify and fill all available niches here thanks to the isolation of the Australian continent for much of mammalian history (pretty much from the early Cretaceous (end of Dino era) onwards, Oz is on its own). At least this is the accepted story.

[tyggerjai.livejournal.com]

I did indeed mean Felidae, thank you.

And you scientists are a whacky bunch, aren't you?
Who calls an animal Caracal caracal caracal ?

And where are Snap snap snap and Pop pop pop?

sol.
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[thorfinn]

I dunno... but I really want a diprotodon () to ride to work on.

[kitling.livejournal.com]

please explain -50 Ma and 5Ma

I'm assuming its a time reference, but google is not helping...

[thorfinn]

I suspect it's Million (years) ago...

[meleah.livejournal.com]

Mega-annum techincally. But yes, essentially million years ago. You just use my or myr for year durations and Ma as a time. So at approximately 50 Ma (the beginning of the Eocene) bats appear in Australia (or so we reckon, records are a little shaky as we don't have many Eocene sites), cos, well, they can fly. At about 5 million years ago, at the begining of the Pliocene, rodents turn up, probably through rafting from the north.

[kitling.livejournal.com]

mega-annum is a cool word

thank you

[bunnikins.livejournal.com]

Your nastybad link filled my screen up with attack-online-gambling popups. I had to club them all to death.

Bad link. No biscuit.

[tyggerjai.livejournal.com]

The Las Vegas City Life?
In hindsight, that's unsurprising :)
My browser told me it had prevented some popups from opening, but since it had prevented them, I ignored it.

sol.
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[meleah.livejournal.com]

Some of us are forced to use IE at work! I forgot pop-ups existed until I got here... :(