# Why no Australian Land Tortoises?



## chosen2030 (May 19, 2014)

Just wondering if anyone can shed some light on the scientific reasons behind why land tortoises do not exist in Australia?


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## Grandpa Turtle 144 (May 19, 2014)

Because God didn't put any there ! 
And not enough grass in the dry season !


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## chosen2030 (May 19, 2014)

Grandpa Turtle 144 said:


> Because God didn't put any there !
> And not enough grass in the dry season !
> 
> 
> Sent from my iPhone using TortForum



As dry as Africa's dry season can be, that still seems odd. Not all of Australia is dry, right? I can't imagine it can be since freshwater turtles exist there. Why no land tortoises in those areas? Just interesting that in a land rich in reptile life that land tortoises are non-existent.


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## dmmj (May 19, 2014)

Aus. deep dark secret, they were eaten by the koalas. Blood thirsty monsters.


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## wellington (May 19, 2014)

Haha. I don't know why, but maybe because there is already so many cool and adorable animals they just didn't need any more


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## Tom (May 19, 2014)

I've wondered this myself. I don't have an answer for you. Let me know if you find one.


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## Grandpa Turtle 144 (May 19, 2014)

Cause torts don't have a spot for a pouch ! 


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## chosen2030 (May 19, 2014)

These replies have hardly been scientific. Anyone have an explanation/insight based on zoology/herpetology?


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## ascott (May 19, 2014)

http://www.wired.com/2010/08/last-giant-land-turtle/

You now have me curious....hmmm, I will share what I find


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## ascott (May 19, 2014)

http://en.wikipedia.org/wiki/Meiolania


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## Merlin M (May 19, 2014)

Could Australia have broken away before tortoises evolved? Just a guess


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## ascott (May 19, 2014)

> Could Australia have_* broken away*_ before tortoises evolved? Just a guess



I am thinking this is the prime factor...still getting it together here....


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## tyguy35 (May 19, 2014)

It's just the same as why there are no vipers there. When the continent shifted the species did not inhabit that area of land. My best guess


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## ascott (May 19, 2014)

http://www.explorebioedge.com/bio-bullets/item/47-the-puzzle-of-a-tortoiseless-australia.html

http://www.explorebioedge.com/bio-e...d-the-australian-tortoise-trump-the-hare.html


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## shanu303 (May 19, 2014)

i believe they did inhabit the land mass of Australia before separation but when geographic isolation of Australia took place and marsupials in Australia evolved the tortoises vanished same as the marsupials vanished from other continents as the other mammals evolved.... i believe the tortoises don't exist now in Australia same way as Australian marsupials aren't found anywhere in the other parts of the world... i believe it happened due to geographic isolation... that's what i studied in my school


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## tortadise (May 20, 2014)

shanu303 said:


> i believe they did inhabit the land mass of Australia before separation but when geographic isolation of Australia took place and marsupials in Australia evolved the tortoises vanished same as the marsupials vanished from other continents as the other mammals evolved.... i believe the tortoises don't exist now in Australia same way as Australian marsupials aren't found anywhere in the other parts of the world... i believe it happened due to geographic isolation... that's what i studied in my school



This is spot on. When Pangea was in place, Australia was actually below Antarctica. North of Australia was Tibet now. The faults more than likely at those points of movements blockaded the land moving reptile there. It was quite a rough area given it's position. It underwent extreme summers, and extreme winters. Thus the marsupial "pouch" animals. Adapted to protect their young better from extreme harsh environmental exposure. 

I will ask my mom to come on and give a good response. She's got a masters in geography and geology and lev this stuff. She may have a good scientific response. Better than mine at least. Ha


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## Moozillion (May 20, 2014)

Interesting thread!


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## FLINTUS (May 20, 2014)

Kelly has summed it up nicely. Due to Australia's geographic position in Pangea, it had very extreme temperatures. It also was not easy to move to for the tortoises, as Kelly said again, there were a number of mountain ranges in that part of Pangea I believe.


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## diamondbp (May 20, 2014)

It is an interesting question without a doubt. I've always wondered what the reason may be. I've also always wondered why there isn't any species of poisonous turtle/tortoise


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## Star-of-India (May 20, 2014)

Now tortoises have colonized many islands, eg., the Galapagos, by floating, likely on debris, out to them. I'd guess the ocean currents between Australia and the mainland are not favorable for that sort of animal dispersal and of course why placental mammals only made it there with the help of humans.


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## ascott (May 20, 2014)

The soil was not appropriate for torts either...seems that is a huge factor...I mean, the torts can get there but can not sustain itself....when burrowing is required the earth in that part is not appropriate in addition to the other factors...


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## dmmj (May 20, 2014)

Sounds to me like you were all fooled by those blood thirsty koalas, pity.


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## shanu303 (May 21, 2014)

Star-of-India said:


> Now tortoises have colonized many islands, eg., the Galapagos, by floating, likely on debris, out to them. I'd guess the ocean currents between Australia and the mainland are not favorable for that sort of animal dispersal and of course why placental mammals only made it there with the help of humans.


i agree..... there is the East Australian Current


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## FLINTUS (May 21, 2014)

Star-of-India said:


> Now tortoises have colonized many islands, eg., the Galapagos, by floating, likely on debris, out to them. I'd guess the ocean currents between Australia and the mainland are not favorable for that sort of animal dispersal and of course why placental mammals only made it there with the help of humans.


But Australia is much further away from Asia than the distance between the different islands of the Galapagoses-they did not float out to the island group, they were on there when they broke away many years ago, and have just floated between the islands.
Same with mammals, while some have been introduced, it is due to plate tectonics and breaking away from the continent.


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## Star-of-India (May 21, 2014)

The Galapagos tortoises did float to the Galapagos. Those are volcanic islands. 

It is true that Australia separated from Gondwanaland, or whatever we call the early mega continent at that very early point in geologic history. Certainly before the placental mammals. 

I work nights in an ER so my brain is a little fuzzy having just gotten off work. But there are tortoises in Southeast Asia, I can't remember whether there are any in New Guinea, which is getting much closer to Australia and was certainly the embarkation point of the Australian aborigines. They are finding fossils/proto-fossils of tortoise-like, or very primitive tortoises, on many of the South Pacific islands whose doom clearly came at the hands of early human explorers, I believe those are thought to have floated to those islands too. Certainly the volcanic ones. 

I have heard of any found in Australia. -Not that by any means signifies that such fossils haven't or won't be found. Australia having been attached to the early mega continent could certainly have gotten tortoises overland if indeed tortoises were anywhere nearby at the time of separation. 

But you know, I'm an amateur and hardly expert at any of this. 

Doug


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## Star-of-India (May 21, 2014)

I'm frightened by blood thirsty koalas btw. So please don't even mention them! ;-)


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## Yvonne G (May 21, 2014)

You know, I just had to do it!


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## shanu303 (May 21, 2014)

Highly Graphic IMAGE! Viewers Discretion is Advised


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## FLINTUS (May 21, 2014)

Star-of-India said:


> The Galapagos tortoises did float to the Galapagos. Those are volcanic islands.


They are volcanic islands, but I thought they still were part of Pangea of some sort, before the construction of them along the Nazca plate boundary. I may(and I probably am) wrong, but I thought that the land was there before, it was just pushed up by the boundary.


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## LLLReptile (May 21, 2014)

FLINTUS said:


> They are volcanic islands, but I thought they still were part of Pangea of some sort, before the construction of them along the Nazca plate boundary. I may(and I probably am) wrong, but I thought that the land was there before, it was just pushed up by the boundary.



No, they are relatively young islands, and didn't exist when pangaea was around. 
http://www.pbs.org/safarchive/5_cool/galapagos/g22_geo.html

Interesting quote that might be relevant about how tortoises got to the galapagos islands, but not so much Australia - 
"Though the islands are now quite isolated, at 600 miles from the nearest mainland, some biologists believe that the Cocos Ridge, which runs under the sea and extends almost the entire distance from Costa Rica to the northern islands, was once a land bridge. These biologists use this theory to explain how some of the life on the Galapagos Islands arrived there, but it has not yet been proven. "

I've heard the drop bears in Australia are quite terrifying.... 

-Jen


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## Yvonne G (May 21, 2014)

I thought the various methods of protecting one's self from the dropbears was insightful:

Various methods suggested to deter drop bear attacks include placing forks in the hair, having Vegemite or toothpaste spread behind the ears or in the armpits, urinating on oneself, and only speaking English in an Australian accent.


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## LLLReptile (May 21, 2014)

So a bit of google fu...

Started with this fossil record map of how different continents must have been connected. My thought was that turtles/tortoises must have been on a part of Pangaea separated by geography from the rest of the continent.
http://en.wikipedia.org/wiki/File:Snider-Pellegrini_Wegener_fossil_map.svg

Looking back at when turtles/tortoises evolved, it was back before the Triassic, so right smack in the middle of Pangaea's existence.
http://tolweb.org/Testudines

Side note, looks like to find where turtles were from, you look for people looking for how they evolved their shells. They clearly were on the African continent - http://www.elsevier.com/connect/how-the-turtle-got-its-shell-clues-revealed-by-fossils

If I had to make a guess, Australia just separated before tortoises/turtles could make it to the part of the mega continent that Aus is on. 

Anyway, if anyone else finds those links interesting, there you go!

-Jen


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## Cowboy_Ken (May 21, 2014)

Yvonne G said:


> I thought the various methods of protecting one's self from the dropbears was insightful:
> 
> Various methods suggested to deter drop bear attacks include placing forks in the hair, having Vegemite or toothpaste spread behind the ears or in the armpits, urinating on oneself, and only speaking English in an Australian accent.



Be warned though. Urinating on ones self, once started, is a hard habit to break. Particularly in the winter when you are cold…


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## chosen2030 (Jun 8, 2014)

Thank you for all of the really well-informed and insightful responses. I am not well versed in Pangaea and what Australia's ecology was like at the time. I've just always wondered since freshwater turtles exist in Australia and because tortoises exist in not-so-distant Burma (with the excellent example given of the Galapagos). I am obviously no ecologist and as a layman didn't see a huge difference between the semi-arid deserts of South Africa and the SW U.S. when compared to those of Australia, but I now have a much better understanding thanks to you learned folks that were willing to share your knowledge with this thread. Much obliged!


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