Tetrapod Zoology

Until recently the Mascarenes were home to an endemic radiation of giant tortoises, the Cylindraspis species. These were entirely separate from the better known, more ‘typical’ Mascarene giant tortoises grouped together in Dipsochelys or Aldabrachelys (Austin & Arnold 2001). Easily the most remarkable Cylindraspis tortoise was C. vosmaeri from Rodrigues, sometimes called the Rodrigues saddle-backed tortoise…

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As you can see from these life-sized models, C. vosmaeri was a veritable giraffe (or sauropod) among tortoises: we have a good idea of its appearance in life thanks to a (very badly) stuffed specimen kept at the MNHN in Paris (shown below). I’d elaborate at length, but (a) I don’t have time, and (b) I’ve cleverly misplaced all my literature on these animals. C. vosmaeri raises loads of questions: about blood pressure and all that, about head and neck posture in terrestrial reptiles, about the evolution of long necks, about niche partitioning, about evolution on islands, and so on.

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And, no, I still haven’t seen Anthony Cheke and Julian Hume’s Lost Land of the Dodo (despite requests for a review copy) to see what they say about these animals. The models shown here were created by Nick Bibby of Rungwe Kingdon and Claude Koenig’s sculpture foundry Pangolin Editions. Pangolin have been working in conjunction with Carl Jones, Nick Arnold, Errol Fuller and Julian Hume to create life-sized sculptures of extinct Mascarene animals.

For previous Tet Zoo articles on tortoises and other chelonians see…

And if you’re interested in long necks and their evolution you must see…

Ref – -

Austin, J. J. & Arnold, E. N. 2001. Ancient mitochondrial DNA and morphology elucidate an extinct island radiation of Indian Ocean giant tortoises (Cylindraspis). Proceedings of the Royal Society of London B 268, 2515-2523.

Comments

#1 David Stern
May 2, 2010

Would they have been able to retract their neck like regular tortoises? It’s hard to imagine that.
#2 sarah jane
May 2, 2010

amazing creatures,i never knew these roam the planet untill today.THANK YOU
#3 Jaime A. Headden
May 2, 2010

“C. vosmaeri raises loads of questions: [...] about head and neck posture in terrestrial reptiles[....]

Astute anatomists will note that unlike typical tortoises and turtles, the anterior carapace is level on its dorsal surface and has an upward slope anteriorly, which mimicks the articulation of the anterior dorsals and reach of the underlying posterior cervicals. In typical tortoises, contrarily, the shell (and dorsals and cervicals) slop ventrally). It is hard to draw a broad parallel using a small group of adapted tortoises to remark on neck articulation. Even osome ther terrestrially adapted toroises cannot raise the posterior cervicals much beyond an inverted vertical posture beneath the shell.
#4 Jorge Velez-Juarbe
May 2, 2010

Very interesting! I had no idea there were turtles with such elongated necks. Did they achieve this by having more cervical vertebrae or by elongation of these?
#5 David Marjanović
May 2, 2010

Awesome. I had no idea.
#6 Jura
May 2, 2010

I’ve known of the Galapagos saddlebacks (Geochelone nigra hoodensis, G.n.abingdoni, G.n.phantasticus), but was unaware of another group that evolved such amazingly long necks. I’ve always thought these guys warranted comparisons with sauropods; especially when seeing them feed, or fight (like here). I’d love to look at the skeleton of one of these guys.
#7 Chelydra
May 2, 2010

Very interesting! I had no idea there were turtles with such elongated necks. Did they achieve this by having more cervical vertebrae or by elongation of these?

If I’m not mistaken, turtles always have eight neck vertebrae. It’s actually very common for a turtle’s neck to be as long as the carapace or longer, but for most behaviors they hold them partially retracted.
#8 Ian Paulsen
May 2, 2010

HI:
In “The Lost Land of the Dodo”, the authors recognize five species of tortoise:

1) Reunion Tortoise (C. indica)
2) Mauritius High-backed Tortoise (C. triserrata)
3) Carosse Tortoise (C. vosmaeri)
4) Mauritius Domed Tortoise (C. inepta)
5) Rodrigues Domed Tortoise (C. peltastes).
#9 Alan
May 2, 2010

Although the native species are both sadly extinct, the Mauritius Wildlife Foundation has been using Aldabran Dipsochelys tortoises as ecosystem replacements on Isle Aux Aigrettes, where they are trying to re-establish the native fauna and flora (at least the surviving species). The attempt was very succesful, and they have released Aldabran and Madagascan Radiated tortoises on Round Island to control non-native plants (native plants are adapted to resist tortoise browsing and trampling). Of course, these are all being monitored for untoward effects as well. The MWF newsletter is avilable on their website – well worth a read.
#10 Jerzy
May 2, 2010

And how these species hold to DNA studies? Especially supposed species pairs on one tiny island? If I remember “rediscovered” live old Mauritian giant tortoises in captivity turned to be Aldabrans from DNA. Would give cold fever to any paleontologist having nothing but bones to work with…
#11 Darren Naish
May 2, 2010

Jerzy, see…

Austin, J. J. & Arnold, E. N. 2001. Ancient mitochondrial DNA and morphology elucidate an extinct island radiation of Indian Ocean giant tortoises (Cylindraspis). Proceedings of the Royal Society of London B 268, 2515-2523.

- . & Arnold, E. N. 2002. The provenance of type specimens of extinct Mascarene Island giant tortoises (Cylindraspis) revealed by ancient mitochodrial DNA sequences. Journal of Herpetology 36, 280-285.

These studies do find support from DNA that five Cylindraspis species can be recognised. The species-level taxonomy of the other Mascarene giant tortoises has proved far more contentious: I covered this subject here back on ver 1. Justin Gerlach did not agree with me – see the comments!
#12 Mike from Ottawa
May 2, 2010

they have released Aldabran and Madagascan Radiated tortoises on Round Island to control non-native plants (native plants are adapted to resist tortoise browsing and trampling).

It is most wonderful to hear of giant tortoise’s being introduced as biological controls. Thanks, Alan.
#13 NoniMausa
May 2, 2010

I well remember the giant tortoises they used to have at Como Park Zoo in St. Paul, Minnesota. (Sp. ?) They were out loose during the day, wandering around among the crowds. Children rode on them. I don’t know if this was bad for them or not — they didn’t really seem to care.

On one occasion I offered one of these placid creatures an apple. He extended his neck what seemed like 30″, smelled the fruit, took a tiny bite, then opened wide and took the whole thing. The length of his neck and the gape of his maw made me think twice about his capabilities should he get annoyed.

Noni
#14 Noni Mausa
May 2, 2010

Aha! From the history of the Como Zoo:

1958 Toby, the giant Galapagos tortoise, comes to live at Como Zoo. Small children are allowed to ride on Toby’s back. The first Siberian tigers to be raised successfully in captivity are born at Como Zoo.

[...]

1974 The Como Zoological Society is incorporated as a support group for Como Zoo. Toby, the Galapagos tortoise, retires to the Honolulu Zoo, where he still lives today.

Happy ending.
#15 Andrew
May 3, 2010

Amazing creature! I read recently in Gavin Young’s “Slow Boat Home” travel book (published early 80′s) that when he stopped in St Helena, there were captive giant tortoises there (in a garden at some estate/mansion), that had been taken from somewhere in the Indian Ocean (Seychelles maybe?).

Does anyone know if these tortoises are still in St Helena and if anyone ever identified their species and original location?
#16 Jenny Islander
May 3, 2010

Fascinating animal. I’ve learned so much about animal adaptability from this blog: turtle-grass-eating sloths, semi-arboreal shell-crunching gators, and now giraffe-tortoises!

What, in your opinion, might tortoises be capable of given a large land mass and no competition? I am a member of a Yahoo group that likes to kick around ideas for alternate pasts and futures. One of them involved the crustal action that produced the Azores being a bit more lively, so that from about 8 MYA there was a California-sized land mass (Azoria) about where the Azores are. (The Norse are the first to discover it in the early Middle Ages.) As the world’s largest oceanic island, it would have a unique fauna. At the time, I postulated all kinds of diverse and freakish descendants of warm-blooded animals (boar-geese, mouse-wolves, vole-bears, etc.), but dismissed tortoises with, “They get really, really big.” What else might they have become besides, well, really, really big?
#17 David Marjanović
May 4, 2010

What else might they have become besides, well, really, really big?

Check out the meiolaniids.

And the pareiasaurs.
#18 tai haku
May 4, 2010

Re – Giant tortoises as biological controls, there are some Aldabrans on Guana island, BVI which are supposed to be being released as a substitute for the big Caribbean Geochelone sp. I think there are some on a couple of other islands too, presumably because (in addition to the above) they look very cool wandering around a big private island.
#19 Jenny Islander
May 4, 2010

@David #17: Interesting, but they’re “elaborately ornamented tortoises” and (if one accepts the relationship) “tortoises that have no shells.” (Considering the vital role of shells in modern tortoises, I doubt that reevolving shell-lessness is likely even given 8 MY.) I’m thinking of a land mass in which tortoises are _the only_ large herbivores at first, although small rodents and anatids would show up eventually and diversify. (I figure that they would have arrived in Azoria when Azoria was still a string of volcanic islands, before the whole mass was heaved up from the ocean floor, and been evolving ever since; rodent castaways would be more likely to survive to make landfall later, when there was more shoreline to land on.)

Giraffe-tortoises that can stretch their necks up to 3 meters high? Apple-sized tortoises that roam the fragrant Azorian evergreen forests in search of nutritious fungi and low-growing berries? Buoyant tortoises that dive to feed on marine vegetation like the iguanas of the Galapagos? Tortoise-hippos?
#20 Darren Naish
May 4, 2010

Jenny (comments 16 and 19): I think all your ideas are pretty good and plausible. Big giraffoid tortoises seem pretty reasonable to me, but not sauropod-sized things as were done for The Future is Wild. You might be interested to know that there are a few references to speculative turtles out there already. Look at experiment 5 here and Gamarachelys.
#21 Sebastian Marquez
May 4, 2010

Toby, the Galapagos tortoise, retires to the Honolulu Zoo, where he still lives today.

Noni, I volunteer here at the Honolulu Zoo and I just wanted to let you know Toby is doing great. He is in an outdoor enclosure with the rest of the Galapagos Tortoises. Not separated by subspecies however. I had always wondered why Toby always wanted his neck scratched until I they told me about his history around people.
#22 Sebastian Marquez
May 4, 2010

The attempt was very succesful, and they have released Aldabran and Madagascan Radiated tortoises on Round Island…

Alan: any chance that the endemic burrowing boa is still extant?
#23 Bruce J. Mohn
May 5, 2010

Mike Balsai, a squamate specialist told me that a keeper at the Philadelphia Zoo had related seeing a Galapagos Tortoise eating birds. It would open its mouth wide and wait for any bird stupid enough to land in its mouth. I was amazed as I had thought they were completely herbivorous. I wonder if it was eating them for the calcium content? I had a leopard tortoise that used to chew on bones, presumably for that.
#24 Darren Naish
May 5, 2010

Wow – I’m betting this was never photographed Definitely should have been put on proper record. All tortoises will chew on bones or carrion when the opportunity arises. Attenborough’s Life on Earth includes a photo of a giant tortoise (an Aldabran one, I think) eating from another giant tortoise carcass. I also have photos somewhere of the bite marks a pet tortoise left on a bone. Small tortoises eat a lot of snails, shells and all.
#25 Sebastian Marquez
May 5, 2010

There’s a speculative critter for you Jenny: A tortoise covergent with an alligator snapper. Bird catcher extraordinaire.
#26 Alan
May 5, 2010

Alan: any chance that the endemic burrowing boa is still extant?

I am afraid it looks pretty unlikely. My copy of The Lost Land of the Dodo is with someone else at present for me to check, but it has not been seen since 1975. I gather that by the time they had managed to overcome objections to using poisoned bait to rid Round Island of rabbits and rats, the remaining population had vanished. On a slightly brighter note, the other Bolyeriid, Casarea dussumieri, is recovering in numbers and has been bred at Jersey.
#27 Noni Mausa
May 5, 2010

Sebastian, thanks for the Toby update! It’s been not less than 40 years since I last saw him.

I was one of the many who rubbed his neck (I had forgotten till you mentioned it.) He got a dreamy look when having his neck stroked, and would stretch out further and arch his neck like a cat.

Some 18 years ago I got a pair of Eastern Box Turtles, one of whom was missing a foot. Didn’t seem to concern her a bit, I think she was born that way or lost it young. She was a lively and curious gal, always watching people through the glass in case we might drop a melon or something. She adored live goldfish, would charge over to the dish and fish for them. She had large, brown eyes, and a little beaky smile that suited her character. Her mate, alas, was pretty dull.
#28 Dennis
May 9, 2010

Nice one, Darren! –just got back from the field in South Africa to find my favourite critters featured on TetZoo!

@tai haku: You mention Aldabra tortoises (going to be?) used as ‘replacements’ in the Caribbean; I’m very interested to know more about this, if possible? (please email me at dmhansen [at] stanford [dot] edu).

A few tortoise updates: A new book by Craig Stanford, ‘The Last Tortoise’ will be (is?) out soon, on Harvard Uni Press.

We have a couple of papers out/in press, that deal with tortoise taxon substitution, in Mauritius and elsewhere:

Griffiths, C. J., et al. 2010. The use of extant non-indigenous tortoises to replace extinct ecosystem engineers: a restoration tool. – Restoration Ecology 18: 1-7.

Hansen, D. M., et al. in press. Ecological history and latent conservation potential: Large and giant tortoises as a model for taxon substitutions. – Ecography

The Aldabra tortoises (Aldabrachelys gigantea, as non-Bour-Gerlach’s prefer it ) used on Ile aux Aigrettes and Round Island are doing great; they are already breeding on IaA, but only subadults were released on RI, so no action there, yet. As for the burrowing boa, I’m afraid it’s lost. It was last seen in 1975, when a researcher took a wee behind a bush, and picked one up. Ever since, whenever you take a piss on RI, you look around carefully…just in case. However, all the extant RI reptiles are doing very well; including the keel-scaled boa and Guenther’s gecko.

The Aldabra tortoises are definitely omnivorous, and well known to scavenge dead tortoises on Aldabra. I read a story once (sorry, can’t remember where!) about a tortoise that stood up when one of the flightless rails was nearby, luring the rail to go underneath its carapace to remove ectoparasites…-then promptly slammed itself back on the ground, killing the rail in the process, and devouring it with great gusto afterwards! Less dramatic events of successful (for the rails) cleaning events are recounted in a classic paper by Huxley: Huxley, C. R. 1979. The tortoise and the rail. – Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences 286: 225-230.
#29 Dennis
May 9, 2010

Darren, I forgot to point you towards a wonderful reconstruction of C. triserrata (partly based on the statue of C. vosmaeri) that Carl Buell did for us last year; you can see it here: http://plant-animal.org/blog/wp-content/cylindraspis.jpg (standing on top of Mauritius & all).
#30 Dartian
May 10, 2010

Dennis:

I forgot to point you towards a wonderful reconstruction of C. triserrata (partly based on the statue of C. vosmaeri) that Carl Buell did for us last year; you can see it here: [url snipped] (standing on top of Mauritius & all).

Awesome image indeed! Alas, the current Mauritian tortoise stronghold, Ile aux Aigrettes, seems to have sunk beneath the waves…