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Giant flightless bats from the future

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


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Dougal Dixon's Night stalker Manambulus perhorridus, from the 1981 speculative classic After Man.

Of the world’s 5700-odd living species of mammal, more than 1200 are bats, making them the most speciose mammalian group after rodents (of which there are about 2200 species). Bats are phenomenally diverse and occur in most terrestrial environments around the world. Understandably, they’re often compared to birds, and several bat groups – those that eat fruit and those that hunt insects and birds on the wing – are undeniably similar, in ecology, behaviour and some features of anatomy, to some bird groups.

Check out the bizarrely short wings of this Mimetillus (flat-headed bat, mimic bat or narrow-winged bat). Image by Darren Naish, redrawn from a photo in Nowak (1999). Note how the wing form of these bats mean that they plot well apart from other species in wing-loading and aspect ratio: they're marked with a red arrow (graph from Norberg & Rayner 1987). For more on Mimetellus, see links below.

But in one very special respect, bats and birds are remarkably different. Birds have evolved flightlessness on innumerable separate occasions. There are not only such classic flightless bird groups as penguins, dodos, ostriches, emus, kiwi and so on, but also flightless ducks, geese, swans, ibises, cormorants, grebes, cranes, rails, auks, falcons, parrots and songbirds (and this isn’t a complete list). Yet bats, so far as we know, have never evolved flightlessness, despite a history that extends over more than 50 million years, despite the invasion of island ecosystems where flightlessness in birds was incredibly common, and despite an enormous amount of variation in size, ecology and wing form (check out the stupid short wings on the flat-headed bat shown in the adjacent image). The absence of flightless bats from both the modern fauna and the fossil record is weird, but perhaps explainable (read on).

I’m a big fan of speculative zoology, and one meme among the many that populates the world of spec zoo is that of the giant flightless bat (note that, for bats, ‘giant’ means ‘more than a few kg’). As we’ll see, various flightless bat species have appeared in speculative books, TV shows and on websites. The creators of these hypothetical animals have placed them in the far future where things are very different from today. They’re not just giant flightless bats – they’re giant flightless bats from the future.

Shalloth, shown in act of predation. From Dixon (1981).

Speculative zoology more or less went mainstream in 1981 with Dougal Dixon’s After Man (Dixon 1981). Set 50 million years in the future, After Man describes a future Earth inhabited by assemblages of entirely new animals, many of which have evolved from those tough generalists most likely to truly survive the human era (like rats, rabbits and crows). Among the most memorable creatures of Dixon’s future Earth are the flightless bats that have evolved on the Pacific archipelago of Batavia.

Arriving and radiating on the islands before birds were able, the Dixonian future-bats have managed to fill niches in terrestrial, arboreal and marine environments. The most fantastic is the Night stalker Manambulus perhorridus, a bipedal predator about 1.5 m tall that “roams screeching and screaming though the Batavian forest at night in packs”, over-powering mammal and reptile prey. Night stalkers walk on their stumpy hands, their prehensile feet hanging over their shoulders. All traces of wing membranes have been lost, and massive ribbed eared and a huge, spear-shaped nose leaf provide them with excellent echolocation abilities and compensate for their blindness. Batavia is also populated by the seal-mimicking Surfbat Remala madipella, the predatory, tree-climbing Shalloth Arbovespertilio apteryx, and the Flooer Florifacies mirabila. Surfbats are sleek-furred swimmers that cruise underwater with shortened, muscular wings and tail-flaps while shalloths are entirely wingless, sloth-like omnivores with mitten-like hands and a single stabbing claw on each thumb.

The Flooer is a largely sedentary, insectivorous, flightless bat that grows large fragrant ear and nose flaps that mimic flower petals. Flooers sit among flowers, attracting insects and eating them. This description is curious, since it’s uncannily similar to that of another hypothetical mammal of the speculative literature: the Miraculous flower-faced snouter Cephalanthus thaumasios.

Snouters – properly termed rhinogradentians – were famously invented for Harald Stumpke’s 1957 book Bau und Leben der Rhinogradentia, republished in English in 1967 as The Snouters: Form and Life of the Rhinogrades (Stumpke 1967). When I first learnt of the Flooer I assumed, reasonably I think, that Dixon had been inspired by Cephalanthus. After asking him I have to conclude that the two creatures really had ‘evolved’ in parallel: when writing After Man, Dougal had been completely unaware of Stumpke’s book. It’s widely acknowledged that Dixon is the ‘go-to guy’ for speculative zoology, so we all had high hopes for his more recent project: the 2002 TV series The Future Is Wild (see Dixon & Adams 2004). One giant bat did feature in the series – a desert-adapted scavenger termed the Deathgleaner – but it was far from flightless, being a vulture-like soarer with a substantial wingspan.

More recently, a few speculative zoology blogs and websites have also featured flightless or near-flightless future bats. Tim Morris’s Conceptual Zoology features the mouse-sized Running bat Cursochiropteryx diabolis, while Dee Dee Rivera’s Metazoica includes a penguin-like swimming bat and a variety of climbing and ground-running flightless bats – termed cryptopters – endemic to the Hawaiian Islands.

Flightless Hawaiian bats of Metazoica.com. From left to right: Pitheconycteris, Cryptopterus, and Acronurus.

Arborvespertilio, a sloth-like, Hawaiian cryptopter from Metazoica.com.

Descendants of fruit bats, cryptopters include lemur-like, sloth-like and superficially deer-like species, all of which lack any trace of wings, have partially fused fingers, and live in fear of the gigantic flying, predatory bat Cercomoloch.

The biggest speculative giant flightless future bat news of recent years has been the 2007 debut of a nefarious super-predator that has an important role in the various story arcs of the ITV drama series Primeval (five seasons have run so far, the most recent of which was screened in May and June 2011).

My very own poseable action-figure 'Future Predator'. It came from a bargain bin at Toys R Us.

Known only as ‘Future Predator’, the creature concerned is a quadrupedal, long-limbed animal about similar in size to a lion. It’s able to climb, leap, run and rear up bipedally; it walks on its knuckles, has atrophied eyes and (despite lacking obvious external ears) relies almost entirely on echolocation. My first thought on seeing this creature on the TV in 2007 was that it must surely be a giant, macropredatory, flightless bat from Earth’s distant future, and the explanation provided in the episode and accompanying documentary revealed that this is exactly what it is. The designers and animators must be congratulated for creating an imaginary animal that really does have bat-like qualities, despite its size, flightlessness and weird appearance. It runs and springs like a gigantic vampire bat. Storylines involving ‘Future Predator’ have become increasingly complex and involve the efforts of some humans to use the animals as weapons, a temporal paradox regarding the origin of the species, and contamination and alteration of Earth’s timeline following the passage of some of these animals into the geological past.

An owl kills a bat. They do that a lot. Image by Greg Capullo.

Surfbats, night stalkers, cryptopters and Future Predators are, obviously, all very much denizens of fiction. Why haven’t real-world bats ever become flightless? It’s been argued that bat anatomy – involving, as it does, extensive wing membranes and sprawling limb postures – would make the transition to flightlessness a difficult one. However, the main reason may be that bats have simply never had the evolutionary opportunity to lose flight: it has remained crucial to their need to capture prey, to migrate and to avoid predators. And the fact that birds have remained a constant presence throughout the whole of bat history, and have proved even better at colonising remote islands than have bats, probably means that bats have never been ‘released’ from the pressures of predation. Indeed, even bats that are superb aerialists suffer heavily from predation by owls and hawks [adjacent Greg Capullo image from Don’t Forget a Towel].

So, while some bats (notably the Australasian short-tailed bats or mystacinids) are highly able scuttlers and runners, able to fold their wing membranes tightly away, my informed guess is that birds would need to be eliminated before bats could become truly flightless. That might happen one day, but it won’t be anytime soon.

Previous Tet Zoo articles have covered some of the issues touched on here. For more, see…

Refs – -

Dixon, D. 1981. After Man: A Zoology of the Future. Granada, London.

- . & Adams, J. 2004. The Future Is Wild. Dorling Kindersley, London.

Norberg, U., & Rayner, J. 1987. Ecological morphology and flight in bats (Mammalia; Chiroptera): wing adaptations, flight performance, foraging strategy and echolocation. Philosophical Transactions of the Royal Society B: Biological Sciences 316, 335-427.

Nowak, R. M. 1999. Walker’s Mammals of the World, Sixth Edition. The Johns Hopkins University Press, Baltimore and London.

Stumpke, H. 1967. The Snouters: Form and Life of the Rhinogrades. The Natural History Press, New York.

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 darrennaish.wordpress.com. He has been blogging at Tetrapod Zoology since 2006. Check out the Tet Zoo podcast at tetzoo.com! 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. keesey@gmail.com 8:12 pm 11/1/2012

    Maybe it’s not that unusual when you consider that pterosaurs never evolved flightless forms, either (Dixon’s Lank and Flarp excepted). Maybe birds are the odd ones here.

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  2. 2. naishd 8:18 pm 11/1/2012

    Although… there are those suggestions that giant azhdarchids may have been flightless (Don Henderson is no longer the only person reporting mass estimates of c. 500 kg or so).

    Darren

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  3. 3. josimo70 8:50 pm 11/1/2012

    Maybe pterosaurs’ and bats’ patagium “lock” their legs and prevent them to re-evolve back to running and walking limbs. They use their legs to climb and hang instead of standing up. For bats and pteros, quadrupedality seems more plausibly than bipedality.

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  4. 4. THoltz 8:52 pm 11/1/2012

    Mike & Darren,

    That is kind of the inverse of one of Ostrom’s main argument for the “grounds up” model of bird origins: unlike bats & pterosaurs, birds by and large retain fully functioning hindlimb terrestrial locomotion.

    I hoped to get flightless pterosaurs into my “Mesozoic Galapagos” storyline in Reign of the Dinosaurus (the ancestral stage of Dinosaur Revolution), but that story never even got to the storyboard stage.

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  5. 5. THoltz 8:53 pm 11/1/2012

    Josimo70,

    While that might work for rhamphorhynchoid-grade pterosaurs, it seems that the cruropatagium didn’t connect up in between the hindlimbs in pterodactyloids.

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  6. 6. Therizinosaurus 9:59 pm 11/1/2012

    Of course since fossil bats are mostly known from teeth, and isolated islands aren’t the best environments to preserve fossils, maybe it’s not surprising we lack fossil flightless bats.

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  7. 7. Christopher Taylor 10:42 pm 11/1/2012

    When I first learnt of the Flooer I assumed, reasonably I think, that Dixon had been inspired by Cephalanthus.

    There is, of course, the actual flower-faced bat Anthops ornatus. According to Tim Flannery, the face is bright orange in life, but there’s no word on whether it benefits from curious insects.

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  8. 8. Xopher425 10:46 pm 11/1/2012

    Very cool article. Always wanted to become a theoretical exozoologist . . .

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  9. 9. Heteromeles 12:24 am 11/2/2012

    I should point out, to be fair to the birds, that flightlessness is mostly concentrated into a few major lineages such as rails and ratites. I don’t know of a flightless hawk or owl, for example, and I think flightless passerines are rather uncommon. The Stephens Island wren is the only one that immediately comes to mind.

    I’d go so far as to say that, if you looked at birds in the normal size range for bats, there’s probably a low level of flightless “microbirds.” It might even be for the same reasons that Darren proposed that bats all fly (they’re prey that needs to escape, and they need to fly to forage).

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  10. 10. AndreaCau 1:35 am 11/2/2012

    “[B]irds would need to be eliminated before bats could become truly flightless”.

    It’s merely a corollary of the First Law of Mammalogy: “Dinosaurs would need to be eliminated before mammals could become truly cool”.

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  11. 11. R McKenna 2:51 am 11/2/2012

    When pondering the absence of terrestrial bats you focus on the required modification of flight structures, but seem to ignore the dearth of echolocation in terrestrial species in general.

    Echolocation demands a significant energetic cost, and while it has distinct advantages in open water or while in flight, the acoustic return signals are much more cluttered and consequently significantly less useful in terrestrial surroundings.

    An interesting study of echolocation during aerial and terrestrial locomotion is given by http://www.noctilio.com/pdfs/Parsons_et_al_2010.pdf

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  12. 12. naishd 6:38 am 11/2/2012

    Thanks for great comments. Therizinosaurus (Mickey) has a point in comment 6 – that is, it isn’t as if our fossil record of bats is outstandingly complete and many fossil bats are known from scrappy remains. However, we have to base conclusions on data we have; based on what we do have, no evidence for flightlessness, yet.

    Heteromeles (comment 9): yes, the majority of flightless birds are indeed clustered within such lineages as Rallidae. However, avian flightlessness does occur – as I said – across the cladogram, in numerous lineages, and the bird groups that lack flightless representatives are the unusual ones. I’m also not aware of any flightless hawk (accipitrid), but flightlessness has been suggested for some extinct caracaras (members of Falconidae) and for some extinct owls (like Ornimegalomyx). Within passerines, you’re correct about Traversia (Stephens Island wren), but flightlessness was also present in Dendroscansor (another acanthisittid) and the Canary Islands long-legged bunting (Emberiza alcoveri).

    Darren

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  13. 13. naishd 6:45 am 11/2/2012

    R McKenna (comment 11): it’s true, I didn’t discuss echolocation in this article (I should note that the text was originally written for a popular magazine and had to be kept both short and non-technical).

    It’s an interesting idea that a reliance on echolocation may constrain the evolution of terrestriality in bats. However, I can’t see it as a major constraint given that microbats of several lineages are successful denizens of terrestrial habitats where they frequently rely on listening to prey-generated noises (as in plecotins), or even on eyesight (as in megadermatids). In other words, hypothetical terrestrial bats could perhaps switch to these methods entirely for prey detection. And what about the New Zealand mystacinids? They clamber about on the forest floor, crawl through hollow logs and among leaf litter, and yet still used echolocation to detect prey.

    Darren

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  14. 14. JoseD 11:09 am 11/2/2012

    @Naishd

    “Yet bats, so far as we know, have never evolved flightlessness, despite a history that extends over more than 50 million years, despite the invasion of island ecosystems where flightlessness in birds was incredibly common, and despite an enormous amount of variation in size, ecology and wing form”

    I figured it had something to do w/why they evolved flight in the 1st place (Birds to escape ground-dwelling predators; Bats & pterosaurs to get from tree to tree more quickly).

    BTW, out of curiosity, any idea how bats compare to other mammals intelligence-wise? It’s something I’ve been wondering about for a while. This & the previous article got me wondering again. Many thanks in advance.

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  15. 15. Heteromeles 11:16 am 11/2/2012

    I thought some shrews used a simple form echolocation. According to Wikipedia, tenrecs echolocate as well, but there’s not a lot of information on how that was tested or how the ability works.

    I should point out that human echolocation has its own Wikipedia article, so if one is coding a cladogram, humans are an echolocating species…

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  16. 16. vdinets 11:17 am 11/2/2012

    JoseD: I’ve talked about bat intelligence with people who have captive-bred a few species, and they all agreed that behaviorally bats are similar to shrews. For example, they tend to use fixed routes when flying, just like many shrews have fixed foraging routes. If you keep bats in a closed room for a few weeks and then open the door to the next room, it takes them a few days to start venturing out of the familiar space.

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  17. 17. naishd 11:58 am 11/2/2012

    Bat intelligence: I don’t much like talking about intelligence given that opinions are so conflicting (see previous comments on smart dinosaur article about opossums and chickens), that so little ‘hard’ data is on record, and that so many statements on the subject are wholly subjective. Having said that… my impression from anecdotes and limited experience is that bats are ‘intelligent’ as mammals go – quick to learn, behaviourally complex and so on.

    Darren

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  18. 18. John Harshman 12:54 pm 11/2/2012

    Correction: Dixon’s bird was a starling, not a crow. (Or so I remember.)

    And I finally figured out how to sign in again. Curse you, Sci Am.

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  19. 19. BrianL 12:56 pm 11/2/2012

    Hasn’t it been suggested that New Zealand’s Miocene St. Bathans mammal was actually a flightless bat? I can’t recall where I read that though and I suppose that the original ‘multituberculate relative’ identification of said mammal is still considered the consensus opinion, vague though it might be?

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  20. 20. Jerzy v. 3.0. 4:52 pm 11/2/2012

    I would second that echolocation incredibly limits the number of niches which bats can occupy. It works in open habitats (air, sea) but is pretty useless for a ground-living animal with a face an inch or so off the ground.

    In addition, geckos are terrestrial nocturnal insectivores which colonized pretty much every island where flightless bat might evolve.

    A rare case where bats defeat birds is that echolocation seems very good at locating birds in darkness (birds cannot hear ultrasounds, unlike most mammals – a mice can hear bat sonar). So the largest SA bat, false vampire Vampyrum spectrum, is semi-specialized in catching small and medium sleeping birds.

    @15
    My impression is that shrews and tenrecs use echolocation for (crude) orientation, not prey capture?

    @16
    I don’t know of any remarkable examples of bat intelligence, but for completeness: moving on fixed routes completely by memory is common among all small mammals. In rodents and shrews it may be result of the need to run quietly in darkness. In bats it may be related to saving energy on echolocation, camouflage from mammalian predators, or adaptation to live in dense colonies (I guess bats don’t recognize own echo from thousands of others – they simply fly by memory).

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  21. 21. vdinets 5:27 pm 11/2/2012

    Jerzy: many bats don’t use echolocation and happily navigate by sight.

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  22. 22. naishd 7:10 pm 11/2/2012

    Echolocation and the hypothetical evolution of terrestriality: see comment 13.

    Darren

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  23. 23. JoseD 3:45 pm 11/3/2012

    @Vdinets & Naishd

    Many thanks again for sharing what you know.

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  24. 24. David Marjanović 10:09 pm 11/3/2012

    Maybe pterosaurs’ and bats’ patagium “lock” their legs and prevent them to re-evolve back to running and walking limbs. They use their legs to climb and hang instead of standing up.

    Pterosaurs did not hang, and there’s not a lot of evidence for climbing.

    I should point out that human echolocation has its own Wikipedia article, so if one is coding a cladogram, humans are an echolocating species…

    Well, no, we’re polymorphic ( = having both states of the character, or generally more than one state).

    I figured it had something to do w/why they evolved flight in the 1st place (Birds to escape ground-dwelling predators; Bats & pterosaurs to get from tree to tree more quickly).

    Why do you think so about pterosaurs? And as far as birds are considered, stability flapping makes more sense, because it isn’t all-or-nothing. You can fly, or you can’t; and if you can’t, you can’t escape a terrestrial predator by flying away.

    Hasn’t it been suggested that New Zealand’s Miocene St. Bathans mammal was actually a flightless bat?

    Not that I know of. Also, way too few material is known to tell whether it was flightless.

    Bats are, however, known from St. Bathans, IIRC.

    the original ‘multituberculate relative’ identification of said mammal

    What? No. It was found in a polytomy with Monotremata, Multituberculata, Theria and IIRC one or two others.

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  25. 25. JoseD 1:19 am 11/4/2012

    @David Marjanović

    “Why do you think so about pterosaurs?”

    It’s based on what I’ve read (E.g. See “Trees Down” under “BACKGROUND”: http://www.geol.umd.edu/~tholtz/G104/lectures/104aves.html ). Admittedly, I haven’t read as much about pterosaurs as I have dinos.

    “And as far as birds are considered, stability flapping makes more sense, because it isn’t all-or-nothing. You can fly, or you can’t; and if you can’t, you can’t escape a terrestrial predator by flying away.”

    When I said “to escape ground-dwelling predators”, I was referring to WAIR/CFD. Just making sure b/c, in retrospect, I wasn’t very clear. Anyway, I’m guessing that grasping feet & stability flapping were pre-adaptations in paravians for WAIR/CFD (among other things).

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  26. 26. Tayo Bethel 7:44 am 11/4/2012

    Are there any theories as to why other predatory bat are not quite as agile on the ground as vampire bts?

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  27. 27. Heteromeles 3:14 pm 11/4/2012

    @David: I should point out that human echolocation has its own Wikipedia article, so if one is coding a cladogram, humans are an echolocating species…

    Well, no, we’re polymorphic ( = having both states of the character, or generally more than one state)..

    True. I ran into a similar problem when trying to create a phylogeny of mycorrhizal states in plants. Acquired (or learned) traits are a pain to code. The plant example is trying to code for mycorrhizal states in the Ericaceae (heather family) which has at least four known. The problem is that three of the different mycorrhizal symbioses were found on a single Gaultheria plant in South America. How do you code that?

    For animals, analogous problems are things like tool use (do sex toys count as tools?), culture (how much learned behavior counts as culture?), and play. And echolocation in humans.

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  28. 28. farandfew 7:58 am 11/5/2012

    Couldn’t it just be that the reason there aren’t flightless bats is that birds are, in general, a lot better at walking? It doesn’t have to be mechanically impossible to have a flightless bat, just that they’d have to go through an intermediate stage where they were neither able to fly, nor to run, away from danger – or towards prey. Plus, they do actually have to locomote to the point where their prey is, because of their short necks and faces; unlike birds who can often jab out and snap it up.

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  29. 29. David Marjanović 12:41 pm 11/5/2012

    When I said “to escape ground-dwelling predators”, I was referring to WAIR/CFD.

    Oh. The problem with WAIR is that it appears to require the ability to lift the wing above shoulder level; it’s not very clear how widespread that ability was. WAIR may be younger than flight instead of older.

    BTW, Microraptor must have been quite a bad climber, at least as far as climbing tree trunks is concerned.

    The problem is that three of the different mycorrhizal symbioses were found on a single Gaultheria plant in South America.

    This isn’t a problem. You simply code Gaultheria as having those three states. The programs, like PAUP*, have no particular trouble dealing with this.

    For animals, analogous problems are things like tool use (do sex toys count as tools?), culture (how much learned behavior counts as culture?), and play.

    This strikes me as a completely different issue: too vaguely defined characters.

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  30. 30. Heteromeles 3:58 pm 11/5/2012

    @David: if you’re trying to determine when members of a clade “switched” from one symbiosis to another, multiple infections are a bad thing, because PAUP doesn’t really know how to deal with that. Gaultheria is well-embedded in the Ericaceae too, just to throw a monkey-wrench in the whole operation.

    The real problem with some types of mycorrhizae (specifically ectomycorrhizae and arbutoid mycorrhizae, for anyone who cares) is that they appear to be the result of a “pre-adaptation,” meaning that the plant has to have certain (poorly understood) root anatomical features to allow the fungus to grow inside without killing the plant, plus it has to be able to “negotiate” with the fungus (probably through exchange of chemical signals) such that neither symbiote kills the other’s cells (as marked by lysis zones in a few documented failed mycorrhizal infections).

    The plant doesn’t evolve these features in the presence of the fungus. Rather, it has them presumably for some other reason, and they get co-opted into a successful ectomycorrhizal infection. I’m trying to avoid the term preadaptation, but it’s the dark shadow behind all this.

    The problem is that the character that researchers observe is the presence or absence of mycorrhizal structures, which are composed of both fungal and plant tissue. If you’re trying use mycorrhizal data to study the plant evolution , these data can be very misleading.*

    As I noted above, this is similar to studying the evolution of culture or tool use.

    *Why bother? Ectomycorrhizal species have evolved independently at least a dozen times in the plant kingdom, and at least five separate times in the fungal kingdom. That’s the biggest example of convergent evolution I know of, and very few people even know it exists, let alone that how understudied it is.

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  31. 31. Gigantala 8:13 am 11/6/2012

    Has it ever occured that bats and pterosaurs simply never became flightless because of their lanching mechanism?

    Unlike birds, which waste a lot of energy taking off, and have massive hindlimbs that offer extra-useless weight, bats and pterosaurs take off using their forelimbs, and thus don’t need heavy hindlimbs.

    This also allows a much faster take off, and to reach larger sizes.

    On other words, whereas birds need to become flightless to develop ratite-like forms, a pterosaur, for example, wouldn’t necessarily need too. The iconic tapejarids and chaoyangopterids might indeed had been ratite-like in habits.

    Similarly, bats could retain flight in situations birds would have lost it. Whereas flightless wrens existed in New Zealand, their competing ground bats retained flight, despiste being diggers.

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  32. 32. David Marjanović 6:37 pm 11/6/2012

    Ectomycorrhizal species have evolved independently at least a dozen times in the plant kingdom, and at least five separate times in the fungal kingdom. That’s the biggest example of convergent evolution I know of

    Seriously? :-) That’s weaksauce! How about the 100 times viviparity evolved among squamates!

    (This number may be exaggerated by unrecognized reversals to oviparity – but not by much.)

    Anyway, I’m surprised you still call it preadaptation instead of exaptation, I’m still not quite sure what your point is, I wonder why you don’t interpret polymorphism as the shift from one state to the other (the new state has been acquired, the old one hasn’t yet been lost), and I assure you that changing states 12 times among thousands of species means the character actually has quite a good phylogenetic signal.

    On other words, whereas birds need to become flightless to develop ratite-like forms, a pterosaur, for example, wouldn’t necessarily need too.

    Good point.

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  33. 33. Dartian 5:33 am 11/9/2012

    Darren:
    An owl kills a bat. They do that a lot. Image by Greg Capullo.

    How realistic is that illustration? Most* owls aren’t very agile aerial pursuit predators, and typically catch their prey on the ground or the branches of trees (or in the water, in the case of fishing owls). We know from the analysis of pellet contents that owls do indeed prey on bats, but it is my impression that most bats that are taken by owls are caught while they are just emerging from, or returning to, their roosts (or even while they’re still actually at their roosting places) at dusk or twilight – not in mid-air in the darkness of night, as Capullo’s image suggests. Please correct me if I’m wrong.

    * There are some exceptions, such as the northern hawk-owl Surnia ulula which actually does fairly often pursue and catch birds in flight. But, significantly, Surnia is mainly diurnal.

    Tayo:
    Are there any theories as to why other predatory bat are not quite as agile on the ground as vampire bts?

    Not even all vampire bats are as agile on the ground as the common vampire bat Desmodus rotundus. Uniquely among extant bats, Desmodus rotundus is able to ‘run’ (or rather, bound) on the ground; Mystacina can’t do that, and neither can the white-winged vampire bat Diaemus youngi, which is otherwise fairly agile on the ground (Riskin et al., 2006). Desmodus rotundus, incidentally, has been observed in the wild to ‘run’ (rather than fly) after moving prey.

    The results of Riskin et al. (2006), by the way, suggest that both Desmodus and Mystacina can walk just as efficiently on the ground as similar-sized non-flying mammals can. The presence of wings does not by itself seem to be what’s impeding the evolution of terrestriality in bats.

    Reference:
    Riskin, D.K., Parsons, S., Schutt, W.A., Carter, G.G. & Hermanson, J.W. 2006. Terrestrial locomotion of the New Zealand short-tailed bat Mystacina tuberculata and the common vampire bat Desmodus rotundus. The Journal of Experimental Biology 209, 1725-1736.

    Link to this
  34. 34. Pristichampsus 5:21 am 12/18/2013

    BianL – Neville Pledge of the South Australian Museum told me the same thing.

    Link to this

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