# Discussion question: grassland tortoises



## GeoTerraTestudo (Jun 6, 2011)

I have been pondering something, and I would love to hear your ideas on this. As we all know, there are many arid and semi-arid tortoise species out there, occupying desert, scrub, and grassland habitats. Africa has the sulcata and the leopard tortoise; Eurasia has the _Testudo_ species; and North America has the _Gopherus_ species. These animals all have fascinating adaptations, but what really impresses me is that the Russian tortoise (_T. horsfieldi_) ranges farther north into colder climates than any other tortoise in the world. Here is a passage from Lagarde et al. (2001):

"...annual activity (3.5 months) is strongly constrained by the harsh environment ... The Uzbek continental climate limits the annual activity period of _T. horsfieldi_ to only 3 months. Within this 3-month period, ambient temperatures fluctuate strongly each day (from â€“10 to +45Â°C), further limiting activity to a total of 360 h per year. Consequently, steppe tortoises can exploit trophic resources only during 16% of the full food-availability period. In our population, steppe tortoises are clearly more constrained by unfavourable environmental temperatures than by food availability."

This is particularly amazing when you consider that Mediterranean tortoises (the other four _Testudo_ species) require about 1000 hours of sunshine per year; that's about 3x as much time for activity than what Russian tortoises get! Nevertheless, this tortoise species is well suited to the steppes of Central Asia. So here's my question: if one of the _Testudo_ species was able to adapt to the Central Asian steppes, then why weren't any of the _Gopherus_ species able to do the same in North America's steppes (also known as prairie, or the Great Plains)? There is a box turtle that inhabits the Great Plains (the ornate box turtle), but no gopher tortoises. Isn't that strange? I have some thoughts on why that might be, but I'm really curious to hear what you think. Why are there no northern tortoises in North America, the way there are in Eurasia? 

Lagarde, F., X. Bonnet, B.T. Henen, J. Corbin, K.A. Nagy, and G. Naulleau. 2001. Sexual size dimorphism in steppe tortoises (_Testudo horsfieldi_): growth, maturity, and individual variation. _Can. J. Zool._ *79*: 1433â€“1441.


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## Terry Allan Hall (Jun 6, 2011)

Interesting question...


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## ascott (Jun 6, 2011)

Pondering here...will get back to you....hmmmmmm?


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## EricIvins (Jun 6, 2011)

I only have experience with Florida Gopher Tortoises, but I can tell you one thing........They are very soil type specific.......Only one soil type really........

The problem is, that soil type is very condusive for Human consumption.......


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## ascott (Jun 6, 2011)

I believe EricIvins has hit that nail bang on....we have the EXACT epidemic taking over the Desert Tortoise here in California......and in greedy portions.


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## GeoTerraTestudo (Jun 23, 2011)

I agree with the above comments, but I have some more thoughts on the subject, too.

To my knowledge, the ancestor of today's _Gopherus_ tortoises came from the northern Great Plains ... however, this was some 2 million years ago when the climate was milder, so this still does not explain why Central Asia has a northern grassland tortoise, while North America does not.

Here's my hypothesis. According to Lockwood et al. (1994), rainfall in the Great Plains is heavier during the spring, but in Central Asia it is heavier during mid-summer. This, in turn, leads to a greater biomass of insects (grasshoppers) in North America. Maybe having more insect prey and less vegetation is the reason why the Great Plains are home to _Terrapene_ box turtles instead of _Gopherus_ tortoises.

Lockwood, J.A., L. Hong-Chang, J.L. Dodd, and S.W. Williams. 1994. Comparison of Grasshopper (Orthoptera: Acrididae) Ecology on the Grasslands of the Asian Steppe in Inner Mongolia and the Great Plains of North America. _Journal of Orthoptera Research_, No. 2: 4-14.
http://www.jstor.org/stable/3503601


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## Terry Allan Hall (Jun 23, 2011)

GeoTerraTestudo said:


> I agree with the above comments, but I have some more thoughts on the subject, too.
> 
> To my knowledge, the ancestor of today's _Gopherus_ tortoises came from the northern Great Plains ... however, this was some 2 million years ago when the climate was milder, so this still does not explain why Central Asia has a northern grassland tortoise, while North America does not.
> 
> ...



Makes sense.


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## ascott (Jun 23, 2011)

Hi Geo...so here is my theory
The gopherus here in the states have very basic requirements for survival...very basic...they need shelter for the harsh heat/cold...they require occasional rainfall...they require source of food hence the rain provides for the little moisture required for that food to grow.....they require each other for well, you know here is where I believe there in falls the evolutionary downfall if you will...if there is a disruption in their "normal" food type it can take a tortoise several months for their body to develop a new food into viable nutrition...therefore if there is huge amount of rainfall each and every year they will constantly be encountering new food supply as well as fighting the increased amount of wetness in the earth and that coupled with extreme cold temps could lead to respiratory issues,etc (and well no one there to give them antibiotic injections) also they mature sexually at around 15-20 years of age and with their high hatchling failure rate the two alone can be devastating alone...but wait I have more..also then add in us humans and our love for open desert space to off road...to build...to use for commercially cheap property (in some cases free) so their habitat is further desturbed...plant loss hence their need to eat other not normal plants to survive which takes us back to it takes their system so long to make new food viable to their nutritional needs....and with heavier rainfall the insect population increases which starts the predator food chain to increase in those areas as well....
The central asia tortoise has alot of the same obstacles...except they are smaller...they have evolved to thrive out of the burrow for much shorter time...their diet also includes carrion and they also consume their own as well as other creatures "poop" and will consume bone particals along with their grazing....they mature sexually at about 5-7 years of age which is much shorter than gopherus...

I have to say once again that these are just my opinion based on my personal research....just my opinion


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## GeoTerraTestudo (Jun 23, 2011)

ascott said:


> Hi Geo...so here is my theory ... The central asia tortoise has alot of the same obstacles...except they are smaller...they have evolved to thrive out of the burrow for much shorter time...their diet also includes carrion and they also consume their own as well as other creatures "poop" and will consume bone particals along with their grazing....they mature sexually at about 5-7 years of age which is much shorter than gopherus...
> 
> I have to say once again that these are just my opinion based on my personal research....just my opinion



Yes, but Texas tortoises are about the same size as _Testudo_ tortoises (around 5-8 inches long), and yet they are found only in the arid southwestern zone of Texas, and have never evolved a way to inhabit the green grasslands to the north. Their cousins are excellent diggers, but Texas torts just scrape out shallow pallets and stay in the warmer parts of Texas. Why is that? Maybe it's because the green pastures of the Great Plains are deceptively poor in nutritional value for a tortoise. Horsfield's tortoise survives by feeding on forbs (weeds), which are much easier to digest than grass. Could it be that rainfall patterns in America's steppes do not allow as much of a forb biomass to grow there compared to Asia? Maybe this has prevented _Gopherus_ from colonizing America's grassland, the way _Testudo_ has colonized the grasslands of Central Asia.

Or maybe it's just something lacking in _Gopherus_, which is basal and more closely related to _Manouria_ than any other genus. _Manouria_ species living at altitude do have some cold tolerance, but not as much as the Russian tortoise. Maybe there is some constraint preventing _Gopherus_ from developing cold tolerance the way _Testudo_ has. I don't know, but I'm very curious.


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## ascott (Jun 23, 2011)

Hi Geo....yes the texas tort is smaller than say the gopherus species found in ca. az etc....I know that the texas tort has been known to be a meat eater vs the ca/az desert tort does not...I wonder if the texas tort is smaller due to their poor vegetation options as well...as you mentioned they dig pallets in the soil in the grasslands (which use to be rich in variety of nutritious vegetation before almost all turned into agricultural fields) while theymature sexually near 12-15 years of age their life span is only near max of 50-60 years...and as the desert tortoise they are very specific to specific areas....the similarity between the texas and desert tortoise is that they seem to hold fast/thrive in specific areas and when those areas are desturbed in such a way that they can not keep up....well, they don't..they end up on our endangered/threatened to extinction lists.... there are studies done that show the texas torts that linger on the outskirts of the grasslands are much healthier..problem is that those areas will to be consumed and made part of the low nutrition grasslands...so I would say that I agree with your speculation about the grassland being low to no nutrional value...heck here in the Mona e desert it has unfortunately been invaded by the cheat grass, red broke in such a way that there are studies going on that show the desert tortoise as well as rabbits and other desert dwellers are consuming large amounts and getting no nutritional value...so here comes another cycle of studies that will likely show another obstacle for these guys....

Again....these are strictly my shared opinion


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## Terry Allan Hall (Jun 24, 2011)

This is very interesting, guys.


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## GeoTerraTestudo (Jul 18, 2011)

I thought of another possible reason why there might not be a Great Plains tortoise, the way there is a Russian steppe tortoise. In his book, _Mediterranean Tortoises_, Brian Pursall states that there are parts of the Mediterranean Basin that could support tortoises but don't because their soils are poor in limestone (calcium carbonate). Tortoises need a lot of calcium for their shells, so they need to live on limestone soils where the plants will take up a lot of calcium, which will in turn be consumed by the tortoise. Portugal, he states, has the same climate as Spain, but whereas Spain does support Iberian tortoises, Portugal does not, and this is because Portuguese soil contains less calcium than Spanish soil.

Could that be true for the Great Plains? Prairie soil is good for agriculture, but maybe it is calcium-poor. Box turtles can live there, but being omnivorous, maybe they can get their calcium through the animals they eat, whereas tortoises rely completely on vegetation for their nutrition. I guess the way to answer this would be to find out how soil in Kansas compares to soil in Kazakhstan in terms of its calcium carbonate content. You would think Kansas soils would have high levels of calcium because, like the Mediterranean area, the Great Plains is the site of a former inland sea from the Cretaceous Period. However, if enough silt has accumulated over the eons, then maybe that limestone layer is too far down. I'm not sure, but it would interesting to find out.


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## CactusVinnie (Oct 13, 2011)

"The Uzbek continental climate limits the annual activity period of T. horsfieldi to only 3 months. Within this 3-month period, ambient temperatures fluctuate strongly each day (from â€“10 to +45Â°C), further limiting activity to a total of 360 h per year."

Hi all!

I think it's a mistake in interpreting those values- if taken literally, Uzbekistan should be a hell on earth. And that is only Springtime!!
It rather means that during those favorable interval- largely, from March/April to June/July- the extremes are btw. -10 to 45*C. The coldest March morning fall to -10*C, the hottest day in July to 45*C, all in the active season of the tortoises. Not unlike, for instance, some parts of KS, CO or UT, where those temps at those times may be the same. They don't come out earlier due to cold, they don't stay later due to heat and lack of food.


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## CactusVinnie (Oct 13, 2011)

Interesting aspects, but I am pretty sure that the tortoises would naturalise in the Great Plains, esp. Horsfields., given the opportunity. Many carbonatic soils there, and in some regions of the Rockies too. West of Continental Divide is a lot of limestone, so I speculate that the Desert Gopherus is limited by other factors (climatic) to spread further north, than lack of calcium. Also, Russians would be the most appropriate species for that area too- it climbs up to 2300m in Pakistan and Afghanistan.


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## Madkins007 (Oct 13, 2011)

Remember- we DID have tortoises here in Nebraska- a largish one _Stylemys nebrascensis[\i] (http://www.bhigr.com/store/product.php?productid=448 if anyone has a spare $95, I would LOVE one of the replica fossil shells!) There is a site called Toadstool Geological Park (part of the Oglala National Grassland) that features several tortoise shell fossils from roughly 30-40 million years ago, and is not too far from the Hudson-Meng Bison Kill site. The soil is varied, but the presence of limestone suggests good calcium levels 'back then'.

There certainly has been climatic change since then, but another key issue is that there have also been several volcanic events. Much of Nebraska at one point or another was covered with ash from Yellowstone and other regional volcanoes. Thick layers of ash would have been a real problem for tortoises while other fauna could have avoided it in many ways.

I have often thought it would be interesting to see what would happen if you got several acres of suitable soil, plants, etc. in Western Nebraska and let a few hundred Russians loose. I suspect that in a few generations, we would have a strain that was pretty acclimated to our climate._


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## Jacqui (Oct 13, 2011)

Well we do know they can survive Nebraska winters outside.


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## Tiger Cowboy (Oct 13, 2011)

It's an interesting question, but there are so many variables I don't think it's possible to get an answer. The very nature of evolution would make it impossible to answer. 

What you are looking for is convergent evolution, two species from separate but comparable geographical areas and different taxa having similar characteristics to fill a similar niche in the ecosystem, such as some of the boas and pythons. It might be that another species filled the niche that another Gopherus species could have occupied. 

It's possible that the environment is different enough that a tortoise just wouldn't fit. I would like to point out that the great plains we know today are VERY different from the plains of even ~150 years ago. Back then there were bison in vast numbers that would munch and trample huge areas, and there were the Rocky Mountain locusts (largely forgotten now but a large deal back when) that decimated huge areas of the plains, and other species that were introduced or have since gone extinct. Maybe not so great for a tortoise.


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## Terry Allan Hall (Oct 14, 2011)

CactusVinnie said:


> Interesting aspects, but I am pretty sure that the tortoises would naturalise in the Great Plains, esp. Horsfields., given the opportunity. Many carbonatic soils there, and in some regions of the Rockies too. West of Continental Divide is a lot of limestone, so I speculate that the Desert Gopherus is limited by other factors (climatic) to spread further north, than lack of calcium. Also, Russians would be the most appropriate species for that area too- it climbs up to 2300m in Pakistan and Afghanistan.



Agreed...T. horsfieldii could easily colonize quite a bit of the USA, given the opportunity.


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## Jacqui (Oct 14, 2011)

Tiger Cowboy said:


> . It's possible that the environment is different enough that a tortoise just wouldn't fit. I would like to point out that the great plains we know today are VERY different from the plains of even ~150 years ago. Back then there were bison in vast numbers that would munch and trample huge areas, and there were the Rocky Mountain locusts (largely forgotten now but a large deal back when) that decimated huge areas of the plains, and other species that were introduced or have since gone extinct. Maybe not so great for a tortoise.



Or you could look at the bison, the huge range fires, and the locusts in a positive light. These would all cause regrowth and it would be regrowth that would be better for the tortoises then the older plants.  Along with regrowth would be the opportunity for other plants to come into their own until the old growth was back. Those other plants might even be a better quality food for the tortoises.

The bison might stomp on the tortoises, but they could survive that, based on the box turtle I use to have that had a clear cow hoof shell mark.


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## redbeef (Oct 14, 2011)

consider more than just climate and those kind of conditions: if there is something that would compete w/a horsfield 'type' for resources in the great plains area, than that organism may be (or may have been) filling part or all of the 'small tortoise ecological niche' leaving no room for the n. american tortoises to adapt to live in that area/niche.

also, i don't know a lot about the range of the horsfield tortoises aside from country: uzbekistan, afghanistan, part of Iran etc...is it really inhabiting only steppes in these countries or is it in more rugged foothill type terrain? they kind of live in all sorts of terrain, aside from grasslands, don't they?


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## CactusVinnie (Oct 14, 2011)

"According to Lockwood et al. (1994), rainfall in the Great Plains is heavier during the spring, but in Central Asia it is heavier during mid-summer."

Read more: http://www.tortoiseforum.org/Thread-Discussion-question-grassland-tortoises#ixzz1amoQsZMM

Hi, GTT!

Maybe in some parts that is true, but the typical Central-Asian climate, at least the one including most of A.h. habitat, is characterised by autumn-winter-spring rainfall and bone dry summers- that is the main reason why they are active only a short window in early spring to early summer: after that, the scorching heat and lack of rainfall kill all the annual weeds and force the tortoises underground. It is a rodent species too that follows the same pattern, forgot the name. The tulips too !
This can be seen checking the data for: 
*Kazakhstan*- Almaty; Kyrgyzstan- Dzalal-Abad; *Tajikistan*- Dushanbe; *Uzbekistan*- Tashkent, Termez, Nurata; *Turkmenistan*- Ashgabat, Bayram-Ali; *Afghanistan*- Kabul, Mazar-i-Sharif; *Pakistan*- Quetta; *Iran*- Zahedan, Mashhad, Tabriz.

Cheers!


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## GeoTerraTestudo (Oct 14, 2011)

redbeef said:


> consider more than just climate and those kind of conditions: if there is something that would compete w/a horsfield 'type' for resources in the great plains area, than that organism may be (or may have been) filling part or all of the 'small tortoise ecological niche' leaving no room for the n. american tortoises to adapt to live in that area/niche.
> 
> also, i don't know a lot about the range of the horsfield tortoises aside from country: uzbekistan, afghanistan, part of Iran etc...is it really inhabiting only steppes in these countries or is it in more rugged foothill type terrain? they kind of live in all sorts of terrain, aside from grasslands, don't they?



I think there may have been another constrain on tortoises that prevented them from colonizing the Great Plains. _Turtles, Tortoises, and Terrapins_ by Fritz Jurgen Obst describes the steppe tortoise as the most widely distributed tortoise species in the world (for now!), inhabiting both steppes and deserts. These tortoises survive by living on slopes where they can dig their burrows, and have access to water and forbs (non-grass herbs). Without these features (slopes, burrows, water, and forbs), these small tortoises would be unable to survive in that climate. So, my question is, are there parts of North America that provide similar resources? I know we have deserts, grasslands, and hills, but do these areas have "diggable" (well-drained) soils where the tortoises could make their burrows? Are enough of these areas near water? Are forbs abundant enough to support tortoises? If not, then that could be the reason why the Great Plains are home to an omnivorous box turtle, instead of an herbivorous tortoise.






CactusVinnie said:


> "According to Lockwood et al. (1994), rainfall in the Great Plains is heavier during the spring, but in Central Asia it is heavier during mid-summer."
> 
> Read more: http://www.tortoiseforum.org/Thread-Discussion-question-grassland-tortoises#ixzz1amoQsZMM
> 
> ...



Thanks for that information. Yes, one would think that North America's plains would be similar to Central Asia's steppes, but perhaps there are some subtle yet important differences in climate and food availability.

GBTortoises and some other members have said that they find steppe tortoises challenging to breed. I am surprised to hear this, and we have been debating the possible reasons for this in the "Hibernation for Testudo" thread. Some people seem to think that the change in seasons is more abrupt in Central Asia than in the Great Plains. Maybe our spring season really is rainier, and maybe this makes it more difficult for a tortoise coming out of brumation to forage. I don't know.

As I've said, it is my hope to get some land and a bunch of Russian tortoises here in Colorado, where they will hopefully breed pretty readily here, due to environmental matching. But judging by some other people's experiences, it might not be as simple as that. I guess we will have to see.


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## CactusVinnie (Oct 14, 2011)

The soil types in wich A.h. live in Central Asia are various, from rocky, sandy to hard clay. I think that they adapt to borrow exactly to survive even in areas without much features, including plains. Another thing, most of them don't know how to drink!! That make sense, since pooling water is a such rare phenomenon there, that only dew and raindrops can be drinked, but our waterbowls and trays may eventually scare them, not to mention that sometimes they will not drink a drop!
I managed to "teach" them to drink, but they seem to forgot easy . More likely the CB babies will be familiarised with the water-tray.
As for the food, their favoured item for a good part of their active period is the Ranunculacean Ceratocephalus falcatus, a small poisonous weed tha killed some sheeps in Utah- I found that in US you call them "burr buttercup". The weed is already spreading well in the West and Great Plains/Midwest region. If you add bindweed, Taraxacum, Cichorium and other Asteraceae and Leguminosae, plus many other that we don't know about yet, it seems that the menu can be satisfying.
We had a dryish spring this year, and is the first spring here for my A.h.. But as you said, I really worry about a posible rainy one, like the 1997 spring, when I saw "The Crow" with Brandon Lee, and still remember the lyrics: "It can't rain all the time". That kept alive my hope that I will finally see the Sun after endless weeks of rain. I am sure that a spring like that would be no good at all for them... But Bucharest is wetter than most of Colorado, so your rainy springs may not be harmful for your A.h.. 
I wish you luck with your Russians project, I will be thrilled to hear that you succeeded!


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## GeoTerraTestudo (Oct 14, 2011)

Thank you for your optimism, Fabian. It is very encouraging. I was beginning to think that maybe I was naive about the needs of steppe tortoises, but it sounds like they might do well here in a semi-wild state after all.


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## GeoTerraTestudo (Oct 15, 2011)

CactusVinnie said:


> The soil types in wich A.h. live in Central Asia are various, from rocky, sandy to hard clay. I think that they adapt to borrow exactly to survive even in areas without much features, including plains. Another thing, most of them don't know how to drink!! That make sense, since pooling water is a such rare phenomenon there, that only dew and raindrops can be drinked, but our waterbowls and trays may eventually scare them, not to mention that sometimes they will not drink a drop!
> I managed to "teach" them to drink, but they seem to forgot easy . More likely the CB babies will be familiarised with the water-tray.
> As for the food, their favoured item for a good part of their active period is the Ranunculacean Ceratocephalus falcatus, a small poisonous weed tha killed some sheeps in Utah- I found that in US you call them "burr buttercup". The weed is already spreading well in the West and Great Plains/Midwest region. If you add bindweed, Taraxacum, Cichorium and other Asteraceae and Leguminosae, plus many other that we don't know about yet, it seems that the menu can be satisfying.
> We had a dryish spring this year, and is the first spring here for my A.h.. But as you said, I really worry about a posible rainy one, like the 1997 spring, when I saw "The Crow" with Brandon Lee, and still remember the lyrics: "It can't rain all the time". That kept alive my hope that I will finally see the Sun after endless weeks of rain. I am sure that a spring like that would be no good at all for them... But Bucharest is wetter than most of Colorado, so your rainy springs may not be harmful for your A.h..
> I wish you luck with your Russians project, I will be thrilled to hear that you succeeded!



Yep, steppe tortoises appear to eat plants that are poisonous to mammalian herbivores, like buttercups when their parasite load gets too high. They appear to be medicating themselves (see "Article: steppe tortoise diet in the wild"). Then, when their parasite load decreases, they switch back to more palatable plants in the poppy and cabbage families, and especially the sunflower family.

As for water, though, I don't mean that they necessarily drink very much, although they might after a rain (Hermann tortoises have been observed to do this). My pet Russian tortoises rarely drink. Rather, I mean that the water (streams and rivers) support riparian vegetation, which the tortoises eat. Without the forbs that grow near water, deserts and steppes only support grasses and shrubs, which the tortoises can't really eat very much of. That's why they need the water: for the plants that grow near it.

I don't know how the Great Plains compare to the Central Asian steppes when it comes to rivers and streams. If we have fewer of them, then that might explain why there are no native tortoises here.






Madkins007 said:


> Remember- we DID have tortoises here in Nebraska- a largish one _Stylemys nebrascensis[\i] (http://www.bhigr.com/store/product.php?productid=448 if anyone has a spare $95, I would LOVE one of the replica fossil shells!) There is a site called Toadstool Geological Park (part of the Oglala National Grassland) that features several tortoise shell fossils from roughly 30-40 million years ago, and is not too far from the Hudson-Meng Bison Kill site. The soil is varied, but the presence of limestone suggests good calcium levels 'back then'.
> 
> There certainly has been climatic change since then, but another key issue is that there have also been several volcanic events. Much of Nebraska at one point or another was covered with ash from Yellowstone and other regional volcanoes. Thick layers of ash would have been a real problem for tortoises while other fauna could have avoided it in many ways.
> 
> I have often thought it would be interesting to see what would happen if you got several acres of suitable soil, plants, etc. in Western Nebraska and let a few hundred Russians loose. I suspect that in a few generations, we would have a strain that was pretty acclimated to our climate._


_

Yes, it is fascinating how the northern plains used to have a tortoise native to them. But this animal was the ancestor of today's Gopherus species. The environment has changed, but box turtles still live there. However, it has been 2 million years (when the Ice Ages began) since a tortoise has lived in the more northerly parts of America. But that is not the case in Central Asia. Amazing...






Tiger Cowboy said:



It's an interesting question, but there are so many variables I don't think it's possible to get an answer. The very nature of evolution would make it impossible to answer. 

What you are looking for is convergent evolution, two species from separate but comparable geographical areas and different taxa having similar characteristics to fill a similar niche in the ecosystem, such as some of the boas and pythons. It might be that another species filled the niche that another Gopherus species could have occupied. 

It's possible that the environment is different enough that a tortoise just wouldn't fit. I would like to point out that the great plains we know today are VERY different from the plains of even ~150 years ago. Back then there were bison in vast numbers that would munch and trample huge areas, and there were the Rocky Mountain locusts (largely forgotten now but a large deal back when) that decimated huge areas of the plains, and other species that were introduced or have since gone extinct. Maybe not so great for a tortoise.

Click to expand...




redbeef said:



consider more than just climate and those kind of conditions: if there is something that would compete w/a horsfield 'type' for resources in the great plains area, than that organism may be (or may have been) filling part or all of the 'small tortoise ecological niche' leaving no room for the n. american tortoises to adapt to live in that area/niche.

also, i don't know a lot about the range of the horsfield tortoises aside from country: uzbekistan, afghanistan, part of Iran etc...is it really inhabiting only steppes in these countries or is it in more rugged foothill type terrain? they kind of live in all sorts of terrain, aside from grasslands, don't they?

Click to expand...


It is possible that there are other, non-tortoise herbivores that have made it impossible for a tortoises to become established in the Great Plains, e.g. bison. However, Central Asia (at least until historical times) used to have a very similar fauna to North America. Both regions had bovines, horses, camels, and their attendant guild of carnivores. But the gopher tortoises never evolved a "horsfield-type" species the way the testudos did. Could just reflect the random-like nature of evolution. Very hard to say. But I find it fascinating to contemplate. _


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## GeoTerraTestudo (Jan 15, 2012)

redbeef said:


> consider more than just climate and those kind of conditions: if there is something that would compete w/a horsfield 'type' for resources in the great plains area, than that organism may be (or may have been) filling part or all of the 'small tortoise ecological niche' leaving no room for the n. american tortoises to adapt to live in that area/niche.
> 
> also, i don't know a lot about the range of the horsfield tortoises aside from country: uzbekistan, afghanistan, part of Iran etc...is it really inhabiting only steppes in these countries or is it in more rugged foothill type terrain? they kind of live in all sorts of terrain, aside from grasslands, don't they?



Bump - Yes, I'm beginning to think prairie dogs might be a major reason why there are omnivorous box turtles here in North America's steppes, but no tortoises. I think prairie dogs would out-compete herbivorous reptiles here.

Here's a cool picture of _Testudo horsfieldi_ in its natural habitat:


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