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The mystery mammal of Kayan Mentarang

The views expressed are those of the author and are not necessarily those of Scientific American.

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Back in 2005, the discovery of a weird reddish, long-tailed mammal, photographed by a camera-trap at Kayan Mentarang in central Borneo, was announced by the Swiss World Wildlife Fund. I covered the case and how it unfolded back at Tet Zoo ver 1 during January 2007. That’s such a long time ago that now is probably a good time to recycle the whole story. So, here it is again, with updates as and where appropriate. The big deal about the Kayan Mentarang animal is that it was hailed as a possible new species.

If you’re wondering, ‘Kayan Mentarang animal’ is not this creature’s official name. It’s a label that I’ve invented, and one that (in my opinion) is clearly superior to the various other labels that have already been given to the creature. Some writers have referred to it as a cat-fox, while one newspaper article jokingly suggested that it be termed the cat-dog-fox-monkey-lemur.

Though the two photos that feature the Kayan Mentarang animal were taken in 2003, they were not made public until early December 2005 (the second photo, showing the animal from behind, is featured at left). I don’t know why this postponement occurred, but such delays are fairly ordinary given that scientists are often really, really busy, or hesitant to announce controversial news. Then again, some news is deliberately held back until its release might have the most impact. It’s probably not a coincidence that the discovery was announced at the same time as was news that the Indonesian Government plans to start an oil palm plantation in the vicinity of Kayan Mentarang National Park. If you’re not aware of the oil palm problem, now is the time to learn. There’s more about the oil palm menace facing the Kayan Mentarang region in this document.

A viverrid montage (clockwise from top left: Paradoxurus, Genetta, Arctictis, Paguma). licensed under Creative Commons Attribution-Share Alike 3.0 Unported license.

During December 2005 and January and February 2006, features on the Kayan Mentarang animal appeared in most newspapers, in most science magazines, in Science (Holden 2005), and on TV. Led by Stephen Wulffraat, the WWF team confirmed that local people were unaware of the creature; they also noted that none of the mammalogists they’d consulted had been able to identify it. While some biologists noted a vague superficial similarity with lemurs, most concluded that it was a viverrid (that is, a member of the same carnivoran family as civets and genets*). Many viverrid species are highly enigmatic and several have only recently been discovered, have only occasionally been photographed alive, or have even not ever been photographed alive at all (for a nice review see Schreiber 1989). [In adjacent viverrid composite, Genetta by Guérin Nicolas, Arctictis by Tassilo RauPaguma by Denise Chan.]

* Recent phylogenetic studies have agreed that Viverridae of tradition is not monophyletic. Nandinia is not close to civets and genets, but is in fact outside the clade that includes all other feliformians (Gaubert & Veron 2003, Flynn et al. 2005, Gaubert et al. 2005, Wesley-Hunt & Flynn 2005, Agnarsson et al. 2010); oriental linsangs (Prionodon) are not viverrids, but either the sister-taxon to cats (Gaubert & Cordeiro-Estrela 2006, Gaubert & Veron 2003) or the sister-group to the (hyena + (mongoose + Madagascan carnivoran)) clade (Agnarsson et al. 2010). Madagascan carnivorans are also not viverrids but form the clade Eupleridae, regarded as the sister-group to mongooses (Gaubert et al. 2005, Agnarsson et al. 2010).

Image by Wahyu Gumelar.

Thanks to its long tail, gracile proportions, size (comparable to that of a house cat), and general civet-like appearance, the Kayan Mentarang animal soon became widely regarded as a probable new viverrid. The image above, produced by Wahyu Gumelar for WWF Indonesia, was widely reproduced and clearly depicts the animal as a new, hitherto unknown viverrid. The idea that the Kayan Mentarang animal might be a hitherto-undiscovered species is exciting and easy to take seriously, given Borneo’s the size (it’s the third largest island in the world) and the continuing discovery there of many new species.

Historic image of Hose's civet by Joseph Smit, from the original 1892 description. In the public domain. Compare to the photos below.

Other authors also interpreted the animal as a viverrid, but as a member of a known species, not a new one. By far the most popular and widely reported suggestion is that the Kayan Mentarang animal is in fact a member of Hose’s civet Diplogale hosei (originally described as Hemigale hosei but included within Diplogale in 1912), also known as Hose’s palm civet or the Brown musang.

Named in 1892 and known from less than 20 specimens, Hose’s civet is a poorly known, terrestrial, forest-dwelling viverrid. Good observations and photos of this species are few and far between and only one specimen has ever been kept in captivity. She “ate fish, shrimp, chicken and processed meat; she refused fruits and boiled rice” (Hunter & Barrett 2011, p. 82).

Arguing that the Kayan Mentarang animal and Hose’s civet were anatomically similar, Chapron et al. (2006) proposed that the alleged new carnivoran “may not be new”. They clearly weren’t entirely convinced by their own explanation, however, as they also noted that the Bay cat Pardofelis badia (another highly elusive carnivoran: named in 1874, it appeared extinct during the 1980s but was rediscovered in 1992) might also be the true identity of the cryptic creature.

J. Wolf's illustration of the Bay cat, from John E. Gray's original 1874 description (and in the public domain). If you really think that this looks like the Kayan Mentarang animal, methinks you shouldn't be trying to identify mystery mammals from photos.

Nope, that is not a Hose’s civet

Despite the apparent strengths of the Hose’s civet identification (and the fact that it came from an authoritative source: one of the authors in particular – Géraldine Veron – being a noted expert on viverrids), it really was a non-starter for several obvious reasons.

The Kayan Mentarang animal is reddish-brown. Hose’s civet is dark brown or blackish. Chapron et al. (2006) got round this by arguing either that the animal’s colour had been “affected by the flash of the camera”, or that the individual was an unusual colour variant. Both suggestions fail to explain the absence of the pale facial, neck and flank markings present in Hose’s civet. Shuker (2006) noted that – contrary to Chapron et al.’s claims of morphological similarity – the long hindlimbs of the Kayan Mentarang animal made it look more suited for arboreal life than is the predominantly terrestrial Hose’s civet.

Furthermore, the Kayan Mentarang animal has really tiny ears while Hose’s civet has far larger ones, and the Kayan Mentarang animal has a proportionally much longer tail than Hose’s civet. So the idea that the Kayan Mentarang animal is actually a specimen of Hose’s civet is poorly founded and unlikely to be correct. And look at the photo showing the animal from behind. It looks nothing like a civet, nor like a cat, either.

Hose’s civet not so poorly known

Camera-trap image of Hose's civet by WCS Malaysia. One of several camera-trap images of this species obtained in recent years.

Worth noting here is that – while undeniably rarely recorded and poorly known – Hose’s civet is no longer as rarely recorded and poorly known as it was just a few years ago. Observations were published in 2002 (Francis 2002) and 2003 (Dinets 2003), and new records based on camera-trap photos have been reported sporadically since December 2003 (e.g., Wells et al. 2005, Mathai et al. 2010, Matsubayashi et al. 2011, Brodie & Giordano 2011, Samejima & Semiadi 2012).

These photos have gradually shown that Hose’s civet is more widespread across Borneo than previously thought. They’ve also shown that it isn’t limited to montane forest as was thought: it also occurs in lowland rainforest and may even be tolerant of recently logged areas. These data all show that it’s “more common and widespread than previously thought” (Wells et al. 2005, p. 13). During August and September 2011 the species was documented (via the use of camera-traps) in the Schwaner Mountains in Central Kalimantan, a lowland location about 500 km away from the previous nearest place of distribution (Semejima & Semiadi 2012).

The case for the squirrel

Anyway, if the Kayan Mentarang animal isn’t Hose’s civet, what is it? As mentioned above, a new identification has now been published; it’s perhaps the most interesting and surprising idea proposed so far. It would seem that the animal is actually…. a flying squirrel. This idea has been around since March 2006, when Andrew Kitchener published an article on Erik Meijaard’s thoughts about the creature (Kitchener 2006). Meijaard observed that the creature seems to have “the suggestion of a membrane between the front and hind limbs”. I agree, and have always wondered why the animal seems to have such a deep ‘belly’.

In fact the case for the squirrel identity is strong. By tabulating all the morphological features visible in the two photos, and then doing likewise for all 16 similar-sized mammals known from Borneo (they included one Sulawesi viverrid too), Meijaard et al. (2006) showed that the Kayan Mentarang animal agrees in morphological details with two flying squirrels found on Borneo: Thomas’ flying squirrel Aeromys thomasi and the Red giant flying squirrel Petaurista petaurista (taxiderm specimen shown at left).

Of incidental interest in this story is that the squirrel A. thomasi was named by Sir Charles Hose (1863-1929) after Michael Rogers Oldfield Thomas (1858-1929) in 1900, while the civet D. hosei was named after Sir Charles Hose by Michael Rogers Oldfield Thomas. I also like the fact that Meijaard et al. submitted their paper on April 1st: a risky plan that can sometimes delay or derail a submitted manuscript.

Composite of the original photos with Meijaard et al.'s reconstructions produced by Carel Brest van Kempen at Rigor Vitae. Compelling stuff.

Anyway… of the 13 morphological characters available for comparison, A. thomasi matches the Kayan Mentarang animal in 12 of them (the 13th character – orientation of the tail when on the ground – remains unknown for this species). In contrast to viverrids, mongooses, linsangs, mustelids, the Bay cat, the Groove-toothed squirrel (aka Tufted ground squirrel) Rheithosciurus macrotis, and various primates, A. thomasi uniquely agrees with the Kayan Mentarang animal in having a short face, small, rounded ears, a reddish non-patterned coat, a tail that exceeds head and body length, and a rounded tail tip. The two also agree in size (the Kayan Mentarang animal is estimated to be 350-450 mm in head and body length) and limb proportions.

When the two ‘mystery’ photos are looked at with all of this in mind, we see hitherto unappreciated squirreleyness. The way the animal holds its long hindlimbs (referring here to the photo showing the animal from behind) and the suggestion of a patagium now make sense, and the unusual curving shape of the long tail matches the tail posture reported for giant flying squirrels (Meijaard et al. 2006, p. 321): this tail posture is unlike that of viverrids and other carnivorans. The white eye-shine present in the Kayan Mentarang animal reportedly matches that of flying squirrels, “whereas the civets and cats normally have less bright, yellowish or orange eye-shine” (Meijaard et al. 2006, p. 321). To help convince people, Meijaard et al. (2006) provided two paintings of the Kayan Mentarang animal, this time ‘reconstructed’ using A. thomasi to fill in the gaps. The composite shown above, produced by Carel Brest van Kempen at Rigor Vitae, shows Meijaard et al.’s (2006) reconstructions alongside the original photos.

One of the several Myakka 'skunk ape' photos taken by an anonymous person but Copyright 2001 David Barkasy and Loren Coleman. I think the images portray a very clever hoax. Image from CryptoZooNews.

If Meijaard et al. (2006) are correct, then two factors have helped obscure the animal’s true identity. Firstly, there is the frustrating fact that its face is obscured by some vegetation, or, as WWF’s Head of Borneo programme director Stuart Chapman put it, “As with all good yeti shots, there is a leaf that obscures its snout” (Fair 2006). I don’t quite understand the yeti reference, as there aren’t any photos of purported yetis that have leaves in the way… but, then, there aren’t any good yeti photos at all (maybe he was thinking of the Myakka skunk ape photos? Adjacent image courtesy of CryptoZooNews). If this really is a squirrel, we would surely all have realised sooner had we been able to see its pointed, distinctively rodent-type snout.

Secondly, people just aren’t used to seeing flying squirrels walking around on the ground, which isn’t surprising given that forest-dwelling flying squirrels are arboreal animals of the canopy. It stands to reason that a ground-walking flying squirrel looked unfamiliar, even to Bornean locals with good knowledge of wildlife, and to experienced field biologists.

Illustration of Aeromys thomasi (in pose considered more typical for a flying squirrel) by Karen Phillips, from the Field Guide to the Mammals of Borneo (WWF Malaysia).

Of course none of this demonstrates that the Kayan Mentarang animal really is a ground-walking specimen of A. thomasi, and not an unknown species. But I’d say that the case is very good and more likely than the new species hypothesis, or the Hose’s civet hypothesis.

Given that giant flying squirrels are awesome and deeply weird I’m no less impressed by the Kayan Mentarang animal than I was when I thought it likely to be an unusual new viverrid. Some species of Petaurista truly are giants (for squirrels), reaching 2.5 kg and more than 100 cm in total length. Though experts at manoeuvrable gliding, they might undergo periods of occasional flightlessness when, in spring, they gorge on buds and new leaves. Hey, there’s an unfinished series of articles on squirrels in my files – really should get that done some time…

For previous Tet Zoo articles on camera-trapped animals, mystery mammals and similar topics, see…

Refs – -

Agnarsson, I., Kuntner, M. & May-Collado, L. J. 2010. Dogs, cats, and kin: A molecular species-level phylogeny of Carnivora. Molecular Phylogenetics and Evolution 54, 726-745.

Brodie, J. & Giordano, A. 2011. Small carnivores of the Maliau Basin, Sabah, Borneo, including a new locality for Hose’s civet Diplogale hosei. Small Carnivore Conservation 44, 1-6.

Chapron, G., Veron, G. & Jennings, A. 2006. New carnivore species in Borneo may not be new. Oryx 40, 138.

Dinets, V. 2003. Records of small carnivores from Mount Kinabalu, Sabah. Small Carnivore Conservation 28, 9.

Fair, J. 2006. Scientists foxed by new carnivore. BBC Wildlife 24 (1), 30.

Flynn, J. J., Finarelli, J. A., Zehr, S., Hsu, J. & Nedbal, M. A. 2005. Molecular phylogeny of the Carnivora (Mammalia): assessing the impact of increased sampling on resolving enigmatic relationships. Systematic Biology 54, 317-337.

Francis, C. M. 2002. An observation of Hose’s civet in Brunei. Small Carnivore Conservation 26, 16.

Gaubert, P. & Cordeiro-Estrela, P. 2006. Phylogenetic systematics and tempo of evolution of the Viverrinae (Mammalia, Carnivora, Viverridae) within feliformians: implications for faunal exchange between Asia and Africa. Molecular Phylogenetics and Evolution 41, 266-278.

- . & Veron, G. 2003. Exhaustive sample set among Viverridae reveals the sister-group of felids: the linsangs as a case of extreme morphological convergence within Feliformia. Proceedings of the Royal Society of London B 270, 2523-2530.

- ., Wozencraft, W. C., Cordeiro-Estrela, P. & Veron, G. 2005. Mosaics of convergences and noise in morphological phylogenies: what’s in a viverrid-like carnivoran? Systematic Biology 54, 865-894.

Holden, C. 2005. New species in Borneo? Science 310, 1764.

Hunter, L. & Barrett, P. 2011. A Field Guide to the Carnivores of the World. New Holland Publishers, London.

Kitchener, A. 2006. Mystery beast revealed. BBC Wildlife 24 (3), 29.

Mathai, J., Hon, J., Juat, N., Peter, A. & Gumal, M. 2010. Small carnivores in a logging concession in the Upper Baram, Sarawak, Borneo. Small Carnivore Conservation 42, 1-9.

Matsubayashi, H., Bernard, H. & Admad, A. H. 2011. Small carnivores of the Imbak Canyon, Sabah, Malayasia, Borneo, including a new locality for the Hose’s civet Diplogale hosei. Small Carnivore Conservation 45, 18-22.

Meijaard, E., Kitchener, A. C. & Smeenk, C. 2006. ‘New Bornean carnivore’ is most likely a little known flying squirrel. Mammal Review 36, 318-324.

Samejima, H. & Semiadi, H. 2012. First record of Hose’s civet Diplogale hosei from Indonesia, and records of other carnivores in the Schwaner Mountains, Central Kalimantan, Indonesia. Small Carnivore Conservation 46, 1-7.

Schreiber, A. 1989. Mysterious mustelids, very mysterious viverrids. BBC Wildlife 7 (12), 816-823.

Shuker, K. P. N. 2006. Mystery beast in Borneo. Fortean Times 206, 4.

Wells, K., Biun, A. & Gabin, M. 2005. Viverrid and herpestid observations by camera and small mamal cage trapping in the lowland rainforests on Borneo including a record of Hose’s civet, Diplogale hosei. Small Carnivore Conservation 32, 12-14.

Wesley-Hunt, G. D. & Flynn, J. J. 2005. Phylogeny of the Carnivora: basal relationships among the carnivoramorphans, and assessment of the position of ‘Miacoidea’ relative to Carnivora. Journal of Systematic Palaeontology 3, 1-28.

Darren Naish About the Author: Darren Naish is a science writer, technical editor and palaeozoologist (affiliated with the University of Southampton, UK). He mostly works on Cretaceous dinosaurs and pterosaurs but has an avid interest in all things tetrapod. His publications can be downloaded at He has been blogging at Tetrapod Zoology since 2006. Check out the Tet Zoo podcast at! Follow on Twitter @TetZoo.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. BrianL 7:01 am 02/25/2013

    I remember this article from when you first posted it and am glad that I still correctly remembered the gist of it.

    It’s a pity both civets and giant flying squirrels are such obscure creatures. Is it known wether these squirrels are at the maximum size possible for mammalian gliders or are there others even larger? Their temporary ‘glidelessness’ due to overeating would seem to suggest they are operating at the limits of that maximum size. Either that, or at the limits of their own physical ability to glide and not as much at the theoretical size limit for gliders. Is anything known about this?

    Those skunk ape photographs are pretty intriguing too. What’s your personal opinion on them?

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  2. 2. farandfew 7:29 am 02/25/2013

    Yetis aside there is a hugely frustrating probable Saola camera trap photo where the animal seems to have carefully stood in order that a large leaf completely obscured its whole head and neck meaning that nobody really feels confident enough to identify it. It would, were it accepted, be the only photograph of the animal in the wild for 11 years.

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  3. 3. vdinets 8:25 am 02/25/2013

    BrianL: Eupetaurus is a bit larger on average, and heavier (although very few specimens have been studied).

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  4. 4. Jerzy v. 3.0. 9:36 am 02/25/2013

    It is clearly the flying squirrel, especially the membrane on the back of hindlimbs is visible on both photos.

    I was a bit uneasy about this “mystery” hype, because it was quite clear PR trick to get publicity for the conservation campaign. There are many habitats in Himalayas in desperate need of better protection, should some conservationists inform the press that they possibly discovered a Yeti there?

    Would be interested in more post about flying squirrels – another interesting group!

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  5. 5. naishd 1:06 pm 02/25/2013

    Thanks for comments. On the limits of body size for a glider (BrianL, comment 1): there are papers arguing that the energetic costs involved in climbing to height (and then gliding a given distance) approximately equal those involved in walking across the same distance when a mammal reach c. 2.5 kg. This may be the main constraint on glider body size (in an endotherm). Seems I’m remembering this from…

    Dial, R. 2003. Energetic savings and the body size distributions of gliding mammals. Evolutionary Ecology Research 5, 1151-1162.

    The Myakka ‘skunk ape’ photos (comment 1). Loren Coleman reminds me (via twitter) that it’s only fair to cite his extensive discussion of the photos in…

    Coleman, L. 2003. Bigfoot! The True Story of Apes in America. Paraview Pocket Books, New York.

    Incidentally, I really like this book (no, that doesn’t mean that I ‘believe’ in bigfoot), and reviewed it in…

    Naish, D. 2004. Sex and the single sasquatch (review of Coleman). Fortean Times 186, 61.

    Anyway, whatever your personal take on the likely existence of unknown hominids in modern North America, the object in those photos doesn’t look realistic to me: the fur just doesn’t look like a real pelt.

    More later.


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  6. 6. vdinets 1:23 pm 02/25/2013

    Jerzy: I second that. Flying squirrels are fascinating, and seriously understudied.

    BrianL: speaking of Eupetaurus, it shows spectacular mastery of the air, even in incremental weather, so I don’t think it’s close to the size limit. But the limit might be not in the gliding ability itself, but in the neccessity to have longer limbs, be able to fold the membrane in a safe and convenient way, and still navigate the dense canopy. That might explain why the largest glider, Eupetaurus, lives in less obstructed environment of rock walls and park-like coniferous forests, as opposed to dense rainforests (yes, I know, oldgrowth dipterocarp forests are not that dense at mid-levels, but still…)

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  7. 7. vdinets 1:28 pm 02/25/2013

    Darren: but isn’t walking from tree to tree a lot riskier than gliding, especially for a mammal that is too large to be killed by almost any owl species? Not to mention obstructions like streams, windfalls, etc.?

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  8. 8. Tayo Bethel 2:08 pm 02/25/2013

    I’ve heard about giant flying squirrels, but info on them seems to be very thin on the ground. Any chance of a post on giant flying squirrels?

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  9. 9. Dartian 2:57 pm 02/25/2013

    the case for the squirrel identity is strong

    I concur (although I must admit that my initial gut reaction when I first saw this photo years ago was “Unknown species of carnivore/civet!”). However, there is one still thing that I wonder about regarding the ID as a giant flying squirrel.

    people just aren’t used to seeing flying squirrels walking around on the ground

    There are two still photos, so where does the idea that the animal is walking come from? Is it just conjecture or did it leave tracks? My point is that walking doesn’t actually sound like the most likely way for a flying squirrel to move on the ground. My impression is that flying squirrels, or at least the smaller species, typically hop when they are on the ground (like tree squirrels also usually do). Video footage of flying squirrels moving on the ground is surprisingly hard to find, but there is at least this video online, featuring a Eurasian/Siberian flying squirrel Pteromys volans that’s visiting someone’s garden at night to drink from the garden pond. Most of the video shows the animal drinking, but when it moves it moves fast indeed – and it does so by hopping/leaping, not walking. The patagium seems to be much less of an impediment to quick and agile terrestrial locomotion than one would expect.

    Of course, Pteromys is much smaller in size than Petaurista or Aeromys. I suppose it’s possible that larger species of flying squirrels move differently on the ground than smaller ones – but is this indeed the case? Does anyone know? I have tried to find video footage of giant flying squirrels moving on the ground but thus far singularly unsuccessfully.

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  10. 10. Dartian 3:03 pm 02/25/2013

    there is one still thing

    Oops. I meant of course “there is still one thing”…

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  11. 11. Heteromeles 5:47 pm 02/25/2013

    Has anyone assembled a collection of these and other camera trap mishaps and posted them on the “why checking your field of view is a good thing” page of a “Camera traps gone wrong” web page? If not, I suggest such a website is sorely needed as an educational tool.

    Otherwise, I’d say it’s an “analomurid” with tongue stuck *very firmly* in cheek.

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  12. 12. Mythusmage 8:25 pm 02/25/2013

    The front page to your blog still has a problem with the layout; probably something to do with an ad.

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  13. 13. vdinets 11:14 pm 02/25/2013

    Dartian: the only place where giant flying squirrels have been studied in some detail is Japan, so I’d try searching for videos with appropriate Japanes titles.
    Eupetaurus leaves typical sciurid tracks in the snow, which means it hops rather than walks.

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  14. 14. Dartian 3:07 am 02/26/2013

    Vladimir: Thanks for the tip! I didn’t immediately find any such Japanese flying squirrel videos that I’m looking after, but I found instead this video, filmed in Taiwan(?). It shows a red and white giant flying squirrel Petaurista alborufus that’s trying to cross a highway (fortunately successfully). And yes, it moves by small hops on the ground, not by walking.

    It’s also striking how much fluffier that squirrel’s tail is than the tail of the Kayan Mentarang animal (which has a tail that’s almost Pink Panther-like in comparison). I also find it slightly odd that the Kayan Mentarang animal doesn’t carry its tail in the semierect S-shaped fashion so typical of squirrels (at least not in those two pictures). That’s negative evidence, but still… it can’t help but to make me less than 100% comfortable with identifying the Kayan Mentarang animal as a flying squirrel (though I admit that I have no better alternative to offer instead).

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  15. 15. Chabier G. 4:00 am 02/26/2013

    Well, I only know about Asian viverrids by pictures, but it seems strange to me that nobody has thought in this animal as a possible relative of the Sulawesi Giant Civet (Macrogalidia), it’s the first animal that came to my mind when I saw the Kayan Mentarang pictures.

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  16. 16. naishd 4:19 am 02/26/2013

    Thanks for comments. Ok, there are some good reminders here that I really should finish and publish my squirrel articles. Lots on flying squirrels (including on the debate over how many times gliding evolved within Sciuridae – more than once?).

    I’m not seeing anything wrong with the format of the front page (Mythusmage, comment 12) – anyone else getting this?

    Is the Kayan Mentarang squirrel walking or hopping? Good point. I had always thought from its pose in the second photo that it is indeed walking, slowly and awkwardly, but still walking. I get this impression because the right hindfoot looks further forward than the left. However, when all we have is a disjointed set of two stills, we can’t say, and I agree with others than hopping looks likely based on what we know about other flying squirrels. Then again, these squirrels do definitely ‘scamper’ when in the trees, so we can’t be absolutely confident about whatever it is they do when on the ground.


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  17. 17. BrianL 4:26 am 02/26/2013

    That Sulawesi giant civet certainly looks a lot like the animal in the pictures!

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  18. 18. naishd 6:38 am 02/26/2013

    I agree with Meijaard et al. (2006): the mystery Kayan Mentarang animal doesn’t really look like the Sulawesi giant civet. Look at those skin webs along the leading and rear margins of the hindlimbs (in the second photo) and along the belly (in the first photo); the Sulawesi giant civet also has a pointed tail tip (rounded in Kayan Mentarang animal), stripes or bands on its tail (no stripes in Kayan Mentarang animal), and spots on its flanks (no spots in Kayan Mentarang animal).

    By the way, when discussing the style of terrestial locomotion used by giant flying squirrels, we should probably talk of them ‘bounding’, rather than hopping, since the latter implies that all four feet leave the ground simultaneously.


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  19. 19. vdinets 9:19 am 02/26/2013

    Sulawesi giant civet is not reddish, has slightly banded tail, dark tail tip and larger ears.
    Giant flying squirrels differ a lot in tail shape. Aeromys tails are much less fluffy than Petaurista tails. So there’s nothing wrong with the ID of the photo.

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  20. 20. Dartian 5:10 am 02/27/2013

    “Aeromys tails are much less fluffy

    Still seems pretty fluffy to me, at least much fluffier than the tail of the Kayan Mentarang animal. Also, judging by that photo, the tail of Aeromys thomasi should be uniformly coloured rather than becoming noticeably lighter towards the tip (as it does in the Kayan Mentarang animal).

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  21. 21. naishd 5:38 am 02/27/2013

    Dartian (comment 20): compare the tail in that Aeromys photo to the tail in the second photo of the Keyan Mentarang animal. They are – so far as I can tell – easily similar enough to be taken as support for the hypothesized Aeromys identification. I agree with you about the unusually light tail colour (even though other flying squirrels can be quite variable with respect to this): maybe the Keyan Mentarang individual represents an unusually pale/reddish individual.


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  22. 22. Chabier G. 7:02 am 02/27/2013

    In the second picture, the animal looks like walking with a rather sprawling gait, very strange for a viverrid, but not rare if the animal must walk with patagium folds. Otherwise, the hindlimbs seem very long, much longer than the arms, and then we can see a high rump, but the pictures of flying squirrels show the four limbs of this animals having rather similar length. Well, two pictures, each one a partial view of the body, are not enough to identify any mammal.

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  23. 23. naishd 7:15 am 02/27/2013

    Chabier G (comment 22): the animal looks especially tall when seen from behind because we’re looking at it in a digitigrade pose (look: you can see the posterior halves of the soles of its feet). We’re more used to seeing squirrels standing or walking in plantigrade fashion. I think this explains its especially ‘long-hindlegged’ appearance. And I, personally, think we have more than enough data here to come up with a good identification.

    Yay – comment # 23!


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  24. 24. Chabier G. 8:44 am 02/27/2013

    OK, it was only an “aficionado” opinion, obviously an expert can find a lot of features to identify the creature, that are not obvious for somebody like me. Red squirrels in different postures are the only squirrels I’ve seen.

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  25. 25. Tayo Bethel 9:39 am 02/27/2013

    How often do sciurids adopt a digitigrade stance?

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  26. 26. Chabier G. 10:11 am 02/27/2013

    I think this posture may be that of a flushed squirrel bounding after having triggered a flashlight provided phototrap camera

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  27. 27. Dartian 10:20 am 02/27/2013

    I agree with you about the unusually light tail colour [...] maybe the Keyan Mentarang individual represents an unusually pale/reddish individual

    Maybe, but be aware that we’re now approaching Special Pleading Territory. (Meijaard et al. (2006) should have noted that the tail colouration of the Keyan Mentarang animal doesn’t quite match that of a (typical) individual of Aeromys thomasi.)

    Anyway, my main point is this: I agree that the animal in those photos is probably a flying squirrel (and, specifically, probably the species Aeromys thomasi). But the word ‘probably’ is key here. IMO, there are enough uncertainties about those pictures that – unless some pertinent new data are presented – no honest zoologist should proclaim with absolute certainty that this identification is beyond reasonable doubt.

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  28. 28. naishd 10:32 am 02/27/2013

    Dartian: yes, a fair point, though we also have to keep another honest caveat in mind: have any of us seen enough Aeromys specimens to really know how variable (or non-variable) they are with respect to pelt/tail colour?

    As for being appropriately cautious about the squirrel hypothesis, I just re-read my article with this in mind and see that my text is appropriately conservative. There are the statements “If Meijaard et al. (2006) are correct…” and “If this really is a squirrel…”, and of course one of the closing paragraphs is “Of course none of this demonstrates that the Kayan Mentarang animal really is a ground-walking specimen of A. thomasi, and not an unknown species. But I’d say that the case is very good and more likely than the new species hypothesis, or the Hose’s civet hypothesis”. So, I’m in the clear (smiley).


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  29. 29. David Marjanović 10:36 am 02/27/2013

    Sex and the single sasquatch

    Sounds interesting!

    Has anyone assembled a collection of these and other camera trap mishaps and posted them on the “why checking your field of view is a good thing” page of a “Camera traps gone wrong” web page? If not, I suggest such a website is sorely needed as an educational tool.

    Yes! A special category on Failblog!

    The front page to your blog still has a problem with the layout; probably something to do with an ad.

    Use Firefox with Adblock and try again.

    By the way, when discussing the style of terrestial locomotion used by giant flying squirrels, we should probably talk of them ‘bounding’, rather than hopping, since the latter implies that all four feet leave the ground simultaneously.

    English: too many words. Even the native speakers can’t keep up!

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  30. 30. Heteromeles 10:58 am 02/27/2013

    The one semi-serious issue I have with the squirrel hypothesis is the shape of the eye shine: it looks like the eyes are facing forward. I don’t know much about Petaurista aside from photos like the one on Wikipedia, but it doesn’t look like their eyes quite that forward-facing. As an aside, Wikipedia suggests that coat color can be variable, and so can eye-shine color.

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  31. 31. PatriciaJH 11:08 pm 02/27/2013

    Good grief, I thought “squirrel-like, but whadda I know” three or four times before getting to the punchline. In the first picture, the bowing posture and large, forward, spraddled hindlegs made me think of squirrels in this posture. Comparing it to the cat, “that’s not a cat, those hind legs look really squirrel-like” — here what struck me wasn’t just the length, but how spraddled they are in the rear view, and also the lack of meat — while they look powerful from the side, from the back, it’s clear that this is a very lightly built critter, “oh, it has long legs because it’s a tree dweller, that’s why they look so squirrel-like”. The lower-right image here is reminicscent of the mystery critter.
    Looking at the viverrids on google images, none of them has quite the front-rear disproportion, or the almost bipedal reliance on the rear haunches, that the squirrels do. Those that come close still seem to be move more like a four-footed inchworm (see this image) than either squirrels or the mystery critter do. There’s a lot of torso, rather than a lot of haunch/knee.

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  32. 32. Dartian 5:27 am 02/28/2013

    it looks like the eyes are facing forward

    Indeed. To me at least, that’s probably why the first impression upon seeing that picture was ‘Carnivore!’ rather than ‘Sciurid!’. However, it’s very difficult to tell eye position for sure from that dark photo.

    the bowing posture and large, forward, spraddled hindlegs made me think of squirrels in this posture

    But the way that squirrel carries its tail doesn’t match the way the Kayan Mentarang animal carries its tail in the first picture. If that is indeed a large flying squirrel, one would expect its tail to be carried like this, or even like this. Not boldly arched and outstreched for no obvious reason (e.g., display, balance) like that.

    see this image

    That’s an otter, not a viverrid.

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  33. 33. vdinets 1:11 am 03/1/2013

    Sciurids are remarkably diverse in the way they carry their tails, even within genera. For example, in the western USA, some closely related chipmunk and ground squirrel species can be told apart in the field by the tail position, although, of course, this is not 100% reliable.

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