Australian Megafauna survives in Tasmania

This was inspired by something I came across when I was looking up something for the domesticated Australian megafauna thread.

What actually happened: There is some indication that a subset of the extinct Australian megafauna survived on Tasmania for about 4000 years after they died out in Australia, probably because at that time Tasmania was an island, so humans didn't get there for about 4000 years after they colonized Australia.

As the last ice age intensified and locked up more water in glaciers, around 43,000 years ago Tasmania became a peninsula of Australia, which it has been off and on through most of its existence. Humans flooded in and the surviving megafauna died out, though Tasmanian Wolves and devils survived there (as they did in Australia until a few thousand years ago). Tasmania became an island again around 10,000 years ago with the start of the current interglacial.

What might have happened: Let's tweak the land level a bit and have Tasmania remain an island throughout the last 50,000 years. We can put the water gap that stays even during ice ages anywhere between the coast of Australia and Tasmania. For the purposes of this scenario it would be good to have it close to Australia, because the larger Tasmania is during the ice ages the more of the megafauna are likely to survive. Small islands and big animal don't mix well long-term.

So, humans colonize Australia, but can't get to Tasmania without crossing an arm of the ocean. They had to cross a water gap to get to Australia in the first place, but tropical oceans are considerably more hospitable to primitive boat tech than cold temperate ones. Apparently humans didn't cross the historic water gap, so there is a reasonable chance they wouldn't cross this one.

So, some of the big Australian animals survive in Tasmania. Diprotodon itself didn't reach Tasmania, but a couple of horse/Tapir-sized Diprotodon relatives did, along with short-faced kangaroos, marsupial lions, and few other oddities.

So, how long would they survive? There are no signs I'm aware of that the Polynesians ever got to Tasmania, though they might have visited but not stayed due to the incumbent Tasmanians. I don't know if Portugal ever reached Tasmania, though my understanding is that they found parts of Australia. The Dutch definitely discovered Tasmania, so they might be the first to disrupt this marsupial utopia.

Standard disclaimer: Yes, I know that creating a sea channel off of Australia would create butterflies that would probably prevent there being a Portugal or Holland in their historical forms, but messing around with geography is way too much fun to avoid because of butterflies.
 
Geological PODs are to go to ASB forum.

And besides, What is with this sudden resurgence in Megafauna Threads?
 
Geological PODs are to go to ASB forum.

And besides, What is with this sudden resurgence in Megafauna Threads?

The pattern of megafauna extinctions is one of the biggest things that shaped where civilizations developed. Why not explore alternative patterns? Look at big picture stuff to vary the usual diet of "What if King Doesn't Matter won the Battle of Trivial?"
 
I'd suspect that being confined on an island, even on the size of Tasmania would turn these megafauna into pygmyfauna, though perhaps not to the extreme as the dwarf mammoths of Wrangle Island. Also, being on an island would give them far less room to flee when the settlers arrived. Predators would almost certainly be wiped out, and sheep would compete with the grazers.
 
I'd suspect that being confined on an island, even on the size of Tasmania would turn these megafauna into pygmyfauna, though perhaps not to the extreme as the dwarf mammoths of Wrangle Island. Also, being on an island would give them far less room to flee when the settlers arrived. Predators would almost certainly be wiped out, and sheep would compete with the grazers.

Yep. I wouldn't expect the Tasmanian megafauna to survive anything like intact through until now, unless the butterflies from their existence totally changed the pattern of European development.

I'm not sure about pygmy versions. You may be right, which would be kind of cool in it's own right. Thinking it through here. The largest animals involved would be about the size of a horse. The really big diprotodonts didn't make it to Tasmania, apparently. That's on the borderline as far as dwarfing goes other places. Tasmania would be a complete and balanced fauna to start out with and balanced fauna tend to produce less dwarfing.

A lot of dwarfing happens on islands where the ecology is stitched together out of whatever animals happen to get there--toss rats, elephants, and a monitor lizard together and see what ecological niches they grab. A stitched together ecology makes dwarfing easier because the large animals doesn't face the full range of predators and there may not be competitors already in the size range. As an example it's probably harder to develop from a mammoth-sized grazer to a donkey-grazer if there is already a donkey-sized grazer occupying the niche. The donkey-sized grazer is probably better at occupying that size niche. Otherwise the mammoth-sized grazer would have pushed it aside on the mainland.

That's a lot of words to say dwarfing would probably be minimal.
 
Funny you mention goannas (monitors). I read once that some fossils in Australia suggest that the Komodo dragon originated there. A long lost relative of the Giant Ripper Lizard perhaps.
 
Funny you mention goannas (monitors). I read once that some fossils in Australia suggest that the Komodo dragon originated there. A long lost relative of the Giant Ripper Lizard perhaps.

Yeah, I think I remember reading that. Monitors are in somewhat of a different class than most lizards--metabolically capable of being more active, larger brained, etc. They're kind of understudies for mammal predators where they exist, and there have sometimes even been large (nearly Komodo-sized) monitor lizard predators even in the mainland of Asia. Don't know about Africa beyond the Nile monitors.

Quite a few years ago (in the 90s) a team of National Geographics scientists spotted a monitor lizard almost as big as the Komodo dragon in Sulawesi. I haven't seen any more about that since. Hopefully it is still out there waiting to be formally described.
 
I suppose we could make this a tad less ASB by having Australia populated too late for whoever got there first to make it to Tasmania before the channel opened up. Of course then you probably wouldn't have Aborigines as such in Australia.
 
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