Tetrapod Zoology

We flightless primates

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ResearchBlogging.org

Some time during the last several hours (while I was asleep), Tet Zoo reached the three million hits mark. Yes, three million hits in two years (Tet Zoo ver 2 was launched on Jan 31st 2007). A noble achievement, I’m sure you’ll agree. Due to workload and assorted other commitments, I still don’t have anything major new to post (how the hell do the more prolific bloggers do it?), though there was the new salamander thing yesterday – knocked up very quickly on the spur of the moment – and I’ve also just produced a new SV-POW! article. Inspired by a comment Nathan Myers left here recently about the bat diphyly issue, I’ve decided to re-post an old article from ver 1. As with other re-posted pieces, I expect it to be new to some or even most readers given that it was published in 2006. Important: please note that I have not (post-2006) substantially updated or modified the article so, by definition, it is out of date and primarily of historical interest (I did, however, just add some new text on microbat diphyly, as the old text was a bit misleading.. and I added a new bit on Eocene bats as well). However, it serves as useful background reading and generated a lot of interest last time it appeared…

Mention ‘flying primate’ and most zoologists will think you’re referring to the well known, controversial proposal of John Pettigrew of the University of Queensland. Initially basing his conclusions on retinotectal organization (viz, the way in which data from the retina is processed in the brain), Pettigrew (1986) argued that megabats (the group that includes fruit bats like the one shown above) are not close relatives of microbats (the mostly small, mostly insectivorous bats that mostly use echolocation), but that they’re actually flying primates, of a sort (read on). If this is right, then Chiroptera [the proper name for the bats] is not monophyletic, and true flight evolved at least twice among mammals. Furthermore, primates and their close relatives are more diverse than conventionally thought, and include an impressive radiation of hitherto misclassified volant species.

In more detailed papers, Pettigrew (1991) and Pettigrew et al. (1989) marshaled evidence from eye, brain and spinal cord anatomy, fore- and hindlimb, finger and metacarpal proportions, and haemoglobin sequences, and again concluded that megabats and primates shared a common ancestor. Microbats, they argued, were not close relatives of megabats and must have affinities elsewhere. Pettigrew et al. (1989) further argued that colugos (aka flying lemurs, or dermopterans) were also part of the megabat-primate clade, and are essentially late-surviving relics which resembled the common ancestor of this group [Sunda flying lemur Galeopterus variegatus (traditionally Cynocephalus variegatus) shown below, from wikipedia. I’ve rotated the image so that the weirdness of the animal is more obvious].

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Pettigrew and colleagues weren’t the first to question bat monophyly: John E. Hill of the then British Museum (Natural History) had done this as early as 1976, Smith & Madkour (1980) argued that micro- and megabats were of separate origins, and Hill & Smith (1984), in one of the best and oft-cited overviews of bat evolution and biology, expressed scepticism of bat monophyly and a preference for megabat-primate affinities (p. 36).

The ‘flying primate’ theory [or hypothesis]… success and failure

Popularly, Pettigrew et al.’s notion that megabats are closer to primates than to microbats became characterized as the ‘flying primate’ theory, and Pettigrew et al. used this term in their papers. This characterization isn’t accurate, however, as Pettigrew et al. (1989) specifically stated that, within their favoured phylogenetic scheme, megabats would be outside of the clade Primates, and thus not primates in the true sense (p. 551).

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I must admit that the ‘flying primate’ theory has a great deal of intuitive appeal, and this probably explains why it’s become both well known and much written about. Colin Tudge wrote about it in The Independent (a British broadsheet newspaper) for example (his article was titled ‘That’s no bat, that’s my brother’), and it isn’t every day that problem areas within the higher-level phylogenetics of placental mammals make it into daily newspapers. Why is the ‘flying primate’ hypothesis intuitively appealing? Perhaps because it appears to have reasonable and easily understood character support and is exciting in contending that a complex and strongly modified bit of morphology – namely the bat wing, with its bizarre elongated fingers and patagial membranes – evolved independently more than once. The fact that it has implications for our own origins might add to its popular appeal (read on).

The accompanying image by Peter Schouten, commissioned by John Pettigrew, depicts the ‘flying primate’ hypothesis in graphic form: note that colugos and megabats branch off from the primate lineage, and aren’t alongside microbats. This image is borrowed from Pettigrew’s Neuroscience UQ site.

However, from the start most bat experts had a problem with the concept: Wible & Novacek (1988) showed how numerous skeletal and soft tissue features ‘strongly support the inclusion of megabats and microchiropterans within the single order Chiroptera’ (p. 1). Simmons et al. (1991) argued that Pettigrew’s entire approach to the bat monophyly question was flawed (in that it seemed based on the assumption that one bit of data – like retinotectal organization – could outweigh all the rest), Thewissen & Babcock (1992) argued that the detailed anatomy of wing musculature best supported bat monophyly, while Bailey et al. (1992) and Ammermann & Hillis (1992) found that genetic data better supported the case for bat monophyly than that for diphyly. Bailey et al.’s paper was even titled ‘Rejection of the ‘flying primate’ hypothesis’, and in an accompanying news piece in Science Ann Gibbons wrote how the ‘flying primate’ hypothesis was ‘heading for a crash landing’. A comprehensive overview of all the data supporting bat monophyly was provided by Nancy Simmons (1994).

Horseshoe bats and kin group with megabats

DNA-based studies later published by Pettigrew and his colleagues produced a new, even more surprising result: rhinolophoids (the horseshoe bats and their relatives) were consistently found to group together with megabats, the implication now being that Microchiroptera might be non-monophyletic* (Hutcheon et al. 1998, Kirsch & Pettigrew 1998, Pettigrew & Kirsch 1998). The existence of a rhinolophoid-megabat clade has also been supported by other research teams (e.g., Teeling et al. 2000, 2002, Liu et al. 2001) but note that many of these studies (Hutcheon et al. 1998, Teeling et al. 2000, 2002, Liu et al. 2001) did not support Pettigrew’s idea of chiropteran diphyly [cladogram below, from Hutcheon et al. (1998), shows megabats forming a clade with rhinolophoids. Hutcheon & Kirsch (2006) proposed that the names Pteropodiformes and Vespertilioniformes should be used for the two major clades of crown-group bats].

* I struggle to appreciate in this case whether the group is non-monophyletic or merely paraphyletic. After all, Microchiroptera is still there: it just turns out that a supposedly distinct group (Megachiroptera) is nested within it. Help me out.

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Let’s suppose for a moment however that Pettigrew and colleagues are right, and that neither Chiroptera nor Microchiroptera are monophyletic. Suppose also that bats are members of the placental mammal group Archonta – an idea that was quite widely accepted until recently (read on). Archonta was first named by William King Gregory in 1910* to house Scandentia (tree shrews), Chiroptera, Dermoptera and Primates (Gregory also included sengis/elephant shrews within Archonta, but they were later removed from it as their affinities clearly lie elsewhere). As the only mammalian clade whose constituent groups are all tied to a climbing lifestyle, it was always very nice to have the bats in there, given that an arboreal origin for bat flight has always been favoured by everyone who’s ever pondered the issue.

* It’s always been problematical that archontan monophyly has only ever been supported by two morphological characters: the anatomy of the penis, and the shape of one of the facets on the astragalus. By their genitals and ankles ye shall know them. If you’re wondering, Archonta means ‘ruling beings’. Yuck.

As you see from the little cladogram I’ve knocked up here, bat diphyly and archontan monophyly makes it at least possible – and phylogenetically parsimonious – that flight was primitive for the megabat-primate clade, or in other words that primates are secondarily flightless. That’s right: you and me, and other apes, and lemurs, tarsiers and monkeys all descend from flying, winged proto-primates. If I were George Olshevsky I might dub this the ‘Bats Come First’ model [now you know what I’m talking about: see The ‘Birds Come First’ hypothesis of dinosaur evolution and Birds Come First – oh no they don’t!]

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But, no, it wasn’t to be. Bat diphyly is not currently favoured by the evidence, and even Archonta has now fallen by the wayside: DNA-based phylogenies now indicate that, while Scandentia, Dermoptera and Primates probably do form a clade – the newly dubbed Euarchonta – bats aren’t close relatives of euarchontans at all. Instead they go elsewhere within the placental mammal clade Laurasiatheria, being (most surprisingly) closest to carnivorans, perissodactyls and artiodactyls (e.g., Murphy et al. 2001, Liu et al. 2001). And what of the idea that microbats aren’t monophyletic? One recent review found that this arrangement was not as well supported by the data as is the traditional view of microbat monophyly (Jones et al. 2002): however, this was a supertree analysis and hence its results were heavily skewed by the fact that ‘the majority of source topologies support microbat monophyly’ (p. 223). Other morphological and molecular analyses have provided further support for the monophyly of a rhinolophoid + megabat clade that is nested within a monophyletic Chiroptera (e.g., Teeling et al. 2005, Hutcheon & Kirsch 2006, Simmons et al. 2008).

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As always the full story that I wanted to cover is even more complex than what’s related here. I haven’t even mentioned the paromomyids: a group of Eocene euarchontans proposed at one time to be colugo-like gliders and thus implicated in the issue of primate and colugo origins. Nor have I discussed the little nyctitheres, a poorly known and long-mysterious Eocene-Oligocene group that appear to have been primitive, scansorial relatives of euarchontans. In fact comparison of nyctitheres with bats and euarchontans led Hooker (2001) to restate the case for archontan monophyly, with Deccanolestes from the Late Cretaceous of India being the oldest member of the group according to his study. Genetic data clearly doesn’t favour archontan monophyly right now, but there is still at least some morphological support for it. A common problem (and, since this article was written, we have a new, particularly primitive bat: Onychonycteris finneyi from the late early Eocene of Wyoming (Simmons et al. 2008). Shown here, acting as covergirl/boy (from wikipedia). It now seems that Onychonycteris and other early bats (Icaronycteris, Archaeonycteris, Hassianycteris and Palaeochiropteryx) are basal to a chiropteran crown-group that includes all extant forms including megabats).

Update (added 5-8-2006): a new paper just published by Nishahara et al. (2006) has reported new genetic support for a laurasiatherian clade composed of bats, perissodactyls, carnivorans and pangolins. They name this clade Pegasoferae, a name derived by uniting Pegasus (in their view a sort of bat-perissodactyl combination) with Ferae (the name they use for the carnivoran + pangolin clade).

For previous Tet Zoo articles on bats see…

Refs – –

Ammerman, L., & Hillis, D. (1992). A Molecular Test of Bat Relationships: Monophyly or Diphyly? Systematic Biology, 41 (2), 222-232 DOI: 10.1093/sysbio/41.2.222.

Bailey, W. J., Slightorn, J. L. & Goodman, M. 1992. Rejection of the ‘flying primate’ hypothesis by phylogenetic evidence from the globin gene. Science 256, 86-89.

Hill, J. E. & Smith, J. D. 1984. Bats: a Natural History. British Museum (Natural History), London.

Hooker, J. J. 2001. Tarsals of the extinct insectivoran family Nyctitheriidae (Mammalia): evidence for archontan relationships. Zoological Journal of the Linnean Society 132, 501-529.

Hutcheon, J. M. & Kirsch, J. A. W. 2006. A moveable face: deconstructing the Microchiroptera and a new classification of extant bats. Acta Chiropterologica 8, 1-10.

– ., Kirsch, J. A. W. & Pettigrew, J. D. 1998. Base-compositional biases and the bat problem. III. The question of microchiropteran monophyly. Philosophical Transactions of the Royal Society of London B 353, 607-617.

Jones, K. E., Purvis, A., MacLarnon, A., Bininda-Emonds, O. R. P. & Simmons, N. B. 2002. A phylogenetic supertree of the bats (Mammalia: Chiroptera). Biological Reviews 77, 223-259.

Kirsch, J. A. W. & Pettigrew, J. D. 1998. Base-compositional biases and the bat problem. II. DNA-hybridization trees based on AT- and GC-enriched tracers. Philosophical Transactions of the Royal Society of London B 353, 381-388.

Liu, F.-G. R., Miyamoto, M. M., Freire, N. P., Ong, P. Q., Tennant, M. R., Young, T. S. & Gugel, K. F. 2001. Molecular and morphological supertrees for eutherian (placental) mammals. Science 291, 1786-1789.

Murphy, W. J., Eizirik, E., Johnson, W. E., Zhang, Y. P., Ryder, O. A. & O’Brien, S. J. 2001. Molecular phylogenetics and the origins of placental mammals. Nature 409, 614-618.

Nishihara, H., Hasegawa, M. & Okada, N. 2006. Pegasoferae, an unexpected mammalian clade revealed by tracking ancient retroposon insertions. Proceedings of the National Academy of Sciences 103, 9929-9934.

Pettigrew, J. D. 1986. Flying primates? Megabats have the advanced pathway from eye to mid-brain. Science 231, 1304-1306.

– . 1991. Wings or brains? Convergent evolution in the origin of bats. Systematic Zoology 40, 199-216.

– . & Kirsch, J. A. W. 1998. Base-compositional biases and the bat problem. I. DNA-hybridization melting curves based on AT- and GC-enriched tracers. Philosophical Transactions of the Royal Society of London B 353, 369-370.

– ., Jamieson, B. G. M., Robson, S. K., Hall, L. S., McAnally, K. I. & Cooper, H. M. 1989. Phylogenetic relations between microbats, megabats and primates (Mammalia: Chiroptera and Primates). Philosophical Transactions of the Royal Society of London B 325, 489-559.

Simmons, N. B. 1994. The case for chiropteran monophyly. American Museum Novitates 3103, 1-54.

– ., Novacek, M. J. & Baker, R. J. 1991. Approaches, methods, and the future of the chiropteran monophyly controversy: a reply to J. D. Pettigrew. Systematic Zoology 40, 239-243.

– ., Seymour, K. L., Habersetzer, J. & Gunnell, G. F. 2008. Primitive Early Eocene bat from Wyoming and the evolution of flight and echolocation. Nature 451, 818-821.

Smith, J. D. & Madkour, G. 1980. Penial morphology and the question of chiropteran monophyly. In Wilson, D. E. & Gardner, A. L. (eds) Proceedings of the 5th International Bat Research Conference. Texas Tech Press (Lubbock), pp. 347-365.

Teeling, E. C., Madsen, O., Van Den Bussche, R. A., de Jong, W. W., Stanhope, M. J. & Springer, M. S. 2002. Microbat paraphyly and the convergent evolution of a key innovation in Old World rhinolophoid microbats. Proceedings of the National Academy of Sciences 99, 1431-1436.

– ., Scally, M., Kao, D. J., Romagnoll, M. L., Springer, M. S. & Stanhope, M. J. 2000. Molecular evidence regarding the origin of echolocation and flight in bats. Nature 403, 188-192.

Teeling, E. C., Springer, M. S., Madsen, O., Bates, P., O’Brien, S. J., Murphy, W. J. 2005. A molecular phylogeny for bats illuminates biogeography and the fossil record. Science, 307, 580-584.

Thewissen, J. G. M. & Babcock, S. K. 1992. The origin of flight in bats. BioScience 42 (5), 340-345.

Wible, J. R. & Novacek, M. J. 1988. Cranial evidence for the monophyletic origin of bats. American Museum Novitates 2911, 1-19.

Comments

  1. #1 Ian
    July 13, 2009

    Congratulations on the 3 million! That’s quite an achievement.

    Now I’ve insinuated myself into your good graces, can I request a blog? We often hear of a new discovery which reveals the earliest of a group of organisms – like the earliest known dinosaur, etc.

    What I’d love to read about is the last dinosaur – or the last few. What do we know about those? What were they, what were they like, when did they live exactly (well not exactly, but approximately!)?

    I understand that there’s some evidence which suggests that dinos may not have all immediately expired on the impact of the asteroid – that some continued on for another million years or so. Perhaps you could comment on that, too.

    Is there a chance you might be interested enough to put together a blog on that topic for us?

  2. #2 Tor Bertin
    July 13, 2009

    Predicting some sort of crazed rant from George right now.

    Great post.

  3. #3 Tor Bertin
    July 13, 2009

    Ah, just realized that this was a repost.

    Still neat stuff all the same!

  4. #4 Hai~Ren
    July 13, 2009

    Yes, colugos are frikkin’ weird. Haven’t seen one yet though, although it’s said that it’s not difficult to find one while hiking in Singapore’s forest reserves.

  5. #5 Christopher Taylor
    July 13, 2009

    Hutcheon & Kirsch (2006) proposed that the names Pteropodiformes and Vespertilioniformes should be used for the two major clades of crown-group bats.

    Why, when the names Yangochiroptera and Yinpterochiroptera were already out there (Yinpterochiroptera from at least 2001, Yangochiroptera from even earlier)?

    I struggle to appreciate in this case whether the group is non-monophyletic or merely paraphyletic.

    It could be either paraphyletic or polyphyletic. It depends whether the “microchiropteran” characters are plesiomorphic or homoplastic, which would require fossil evidence to determine.

  6. #6 Darren Naish
    July 13, 2009

    Ian (comment 1): I won’t devote a whole blog to end-Maastrichtian dinosaurs, but perhaps a blog post (ha ha). Actually, no plans to do what you suggest right now, but maybe at some point in the future.

    Chris (comment 5): Hutcheon & Kirsch (2006, pp. 6-7) argued that the contents of Yinochiroptera and Yangochiroptera have been so altered since initial inception that the true contents of the groups have become obscure: for example, yinochiropterans as imagined by Smith, Koopman etc. are not monophyletic – some are close to megabats while others are nested within Yangochiroptera. Adding to the problem is that (so far as I can tell) Yinochiroptera and Yangochiroptera were never properly defined phylogenetically: yinochiropterans were just said to be the microbats with the moveable premaxillae and yangochiropterans the ones with fused premaxillae. The groups that possess these characters states do not fall into two neat groups, so what happens?

    A free pdf of Hutcheon & Kirsch (2006), and more explanation, is available here.

    See also…

    Giannini, N. P. & Simmons, N. B. 2007 The chiropteran premaxilla: a reanalysis of morphological variation and its phylogenetic interpretation. American Museum Novitates 3585, 1-44.

  7. #7 Darren Naish
    July 13, 2009

    … I should have added that Giannini & Simmons (2007) did not entirely agree with Hutcheon & Kirsch (2006), as they found a clade that did correspond with Yangochiroptera.

    For those who haven’t realised yet: yes, these bat groups were named on the basis of yin and yang, the complementary opposites within a greater whole.

  8. #8 Jerzy
    July 13, 2009

    Interesting is if echolocation appeared independently twice, or was lost by Pteropodidae?

    Anyway, tube-nosed fruitbat is my favorite little-known creature.

    About colugos – wild ones live in Singapore zoo, but nobody managed to keep one in captivity.

  9. #9 Zach Miller
    July 13, 2009

    Question I haven’t really pondered until now: Where ARE primates on the mammalian family tree, and who are their currently-understood closest relatives?

    Pegasoferae sounds…wierd. Not the name, but the groups involved.

  10. #10 J.S.Lopes
    July 13, 2009

    Tupaias and Colugos have their entire evolutionary history nested in Southeast rainforests. Oldest dermopterans fossils came from Middle-Upper Eocene Thailand and Myanmar, but unfortunately, SOuth Asia didnt provide older sites. Tupaias’ fossil record are still more poor.
    What we can deduce from this meager record is that Scandentia and Dermoptera (sensu strictu, not including Plesiadapiformes) have always been Southeast Asian endemics, never reaching colder latitudes, like euprimates and plesiadapiformes did. Presence of Glires (and allies) in Asia since lower Paleocene (or Cretaceous) point to an Asian origin for Euarchontoglires (=Supraprimates clade).

    Chiropteran record shows a differente pattern: they reached Holarctica in Lower Eocene (like the happy crowd perissodactyles-artiodactyles-euprimates-hyenodonts-fissipedians), but were present at Eocene sites in Australia and South America (maybe Antarctica too), which is amazingly freaky. Proto-bats in Gondwana?

  11. #11 Nathan Myers
    July 13, 2009

    Thank you for re-posting and updating. Bats must be the beetles of Mammalia.

    Off-topic, I only just found out that mongooses and meerkats are opposite the cat/dog divide from weasels and minks. Boggle! My kids will need disabusing now. (Sorry, kids!)

    Speaking of mummification (what? this), mounting a small corpse in the grill of your car works well if you drive much. I had a small bird lodged next to my headlight, with its little feet sticking out, for … well, two years, I think, in the early ’90s. It looked almost as good coming out as it must have done going in.

  12. #12 Robert
    July 13, 2009

    Thanks for putting that article up – I couldn’t help but feel disappointed to discover that the “Bats as Primates” theory did not measure up.

    As you say,the concept has great intuitive appeal – one only has to look at the dog like faces of so many Lemurs, and the strikingly similar faces of Fruitbats to realise the concept, ostensibly, makes a great deal of sense.

  13. #13 Andreas Johansson
    July 13, 2009

    @Zach:

    As Darren wrote in the post, “Scandentia, Dermoptera and Primates probably do form a clade – the newly dubbed Euarchonta”. The next group out is Glires (ie. rodents and lagomorphs), and the next after that is Laurasiatheria, which includes all the other placental mammals except the afrotheres and the xenarthrans.

    The group uniting Euarchonta and Glires has been called, with breathtaking originality, “Euarchontoglires”. Yuck!

  14. #14 Zach Miller
    July 13, 2009

    Yuck indeed. Thanks for clarifying.

  15. #15 Darren Naish
    July 13, 2009

    Thanks for comments. Response to Jerzy (comment 8): as you might imagine, there’s been a lot of debate as to when echolocation evolved. Echolocating bats have larger cochleae (relative to skull width) than non-echolocators, and there are hyoid and ear bone characters that correlate with echolocation too.

    By looking at these features in fossil taxa, workers have shown that stem-bats (like Icaronycteris) probably were echolocators: it therefore seems that the loss of echolocation in megabats is derived, not primitive. The most basal known bat – Onychonycteris – lacks the echolocation characters, so it seems that bats took to flying first, and evolved echolocation later. Fenton’s ‘echolocation first’ hypothesis fails; Norberg’s ‘flight first’ model does well.

  16. #16 Mike from Ottawa
    July 14, 2009

    how the hell do the more prolific bloggers do it?

    By not having two dozen references for a post would be my guess. We come to TetZoo for quality, not quantity and are not disappointed.

  17. #17 Allen Hazen
    July 14, 2009

    Zach Miller–
    (re comment 9) You gotta admit its a cool NAME though! If you think the animals included are a weird assortment, recall that (on the basis of a lot of molecular and a very little bit of morphological evidence) Pangolins are in Pegasoferae too: sister group to Carnivora. I suppose that if the last common ancestor of Pegasoferans had somehow materialized in the first half of the 20th C, I suspect it would have been classified, on morphological grounds, as an “Insectivore.”

    About the same time I first heard of the bat diphyli hypothesis, there was a proposal that Rodentia was not monophyletic: that the South American endemics (Guinea Pig etc etc) were actually closer to Primates than to other Rodents. That hypothesis, too, seems to have fallen by the wayside since.

  18. #18 Michael P. Taylor
    July 14, 2009

    Darren, I don’t understand the distinction you’re making between “non-monophyletic” and “merely paraphyletic” — a paraphyletic group IS, by definition, non-monophyletic. What am I missing?

  19. #19 Darren Naish
    July 14, 2009

    Mike… In short, eh? A monophyletic group includes taxa that descend from a single ancestor, whereas a paraphyletic group is monophyletic but somehow thought not to include one of its sub-clades. Paraphyletic groups are not, by definition, non-monophyletic: they are just ‘incomplete’ due to convention. You might be thinking that the concept of monophyly demands inclusion of all descendants of the common ancestor, but in that case you’re confusing ‘monophyletic group’ with ‘clade’.

    So – if phylogenetic studies find some members of traditional Microchiroptera to group with Megachiroptera, does this mean that Microchiroptera is biphyletic (because some microchiropterans form a clade, while others form a clade with megachiropterans), or paraphyletic (because Microchiroptera of tradition excludes just one of its sub-clades, Megachiroptera)?

  20. #20 Michael P. Taylor
    July 14, 2009

    “You might be thinking that the concept of monophyly demands inclusion of all descendants of the common ancestor, but in that case you’re confusing ‘monophyletic group’ with ‘clade’.”

    Well, one of us is confused, anyway. See for example Box 1 (Terminology) in de Queiroz and Gauthier’s (1994) classic introduction to phylogenetic nomenclature, which says “A paraphyletic taxon consists of a common ancestor and some, but not all, of its descendants; a monophyletic taxon (named clade) consists of a common ancestor and all of its descendents”.

    If you want to to indicate that a taxon is the mere aggregation of two or more clades (or paraphyletic groups), then the term for that is polyphyletic. And both paraphyletic and polyphyletic groups are non-monophyletic. (This is why I am always so rude about the phrase “monophyletic clade” — it’s an exact tautology.)

    (That’s not to deny that the term “monophyletic” has occasionally been used in the looser sense; but that usage, which AFAICT was never very prevalent, is now pretty much extinct. The last time I saw it used was in a Ken Kinman post on the DML!)

  21. #21 Darren Naish
    July 14, 2009

    Yeah, I should have said that ‘monophyletic’ has been used in more than one way, and that I was obviously more influenced by those uses that demanded ‘single ancestor’, rather than ‘all descendants without end’. It’s for this reason that some workers (e.g., Ashlock) used ‘holophyly’ for Hennig’s concept of a group that included ALL descendants of a single ancestor whereas monophyletic taxa could indeed include paraphyletic groups without contradiction.

    However, I take your point that ‘monophyly’ is generally understood to mean ‘single ancestor and ALL descendants’.

  22. #22 Jerzy
    July 14, 2009

    Confused. So, Onychonycteris-like bats -> echolocation -> divergence of ying/yang -> divergence of rhinolophid and pteropodid clades -> loss of echolocation in Pteropodidae?

  23. #23 Darren Naish
    July 14, 2009

    You aren’t really confused, as this sequence is correct :)

  24. #24 chiropter
    July 14, 2009

    I just had to second # 16- props to Darren for producing such a quality blog.

  25. #25 Steve P
    July 14, 2009

    Darren: awesome post, demonstrating to me (once again) that I absolutely must plough through your archives at some point! I had wondered about this idea for some time, since flying foxes are (or at least were) fairly abundant in my area. Convergence strikes again…
    I was going to ask if any mammals other than bats and cetaceans had evolved (at least some form of) echolocation: the Wikipedia article on echolocation referenced an article by Tomasi (1979 – available on jstor) suggesting that the only others were two North American shrews (Sorex and Blarina) and Madagascan tenrecs – have any been discovered since then?

    Tomasi, Thomas E. 1979. Echolocation by the Short-Tailed Shrew Blarina brevicauda, Journal of Mammalogy, 60 (4), pp. 751–759.

  26. #26 Jerzy
    July 15, 2009

    @Steve P

    Some seals? Or it was suggested but turned wrong?

    BTW – some cleverdick should look for evidence of echolocation in Mesosoic marine reptiles. Adaptations are so obvious that checking for them should be relatively easy.

  27. #27 Darren Naish
    July 15, 2009

    BTW – some cleverdick should look for evidence of echolocation in Mesosoic marine reptiles.

    It’s been done. Despite (erroneous) suggestions of a melon in some ichthyosaurs, no evidence for echolocation or for specialised hearing in Mesozoic marine reptiles. They either used bone-conducted hearing (in which case directional hearing was poor or virtually absent) or reduced or even lost various parts of the ear (the stapes is absent in some plesiosaurs, for example). Having said that, I do have access to an unpublished manuscript on ichthyosaur ears and really must read it some time…

  28. #28 Nathan Myers
    July 16, 2009

    Homo, too, has evolved echolocation. I’m practicing. Blind people can take classes in it now.

  29. #29 Dartian
    July 17, 2009

    Darren:

    I must admit that the ‘flying primate’ theory has a great deal of intuitive appeal

    Interesting that you say so, because for me it was, and still is, quite the opposite: when I first heard of the ‘flying primate’ hypothesis it struck me as rather counterintuitive. But that probably only reflects my own Northern Hemisphere bias. In my mind, the ‘default bat’ is a microchiropteran, and specifically a vespertilionid. And, if anything, a typical microbat reminds me of a flying shrew rather than of a flying primate or anything else. Could it be, I wonder, that someone who’s more intimately familiar with pteropodid fruit bats (e.g., by living somewhere where they are endemic, such as in Australia) and who might therefore consider them more representative chiropterans, is also more likely to find a bat-primate link intuitively appealing*?

    * Note that I’m just frivolously speculating here, and not suggesting that any such factors have actually been influencing John Pettigrew’s work.

    If I were George Olshevsky I might dub this the ‘Bats Come First’ model

    Interestingly however, the question of bat origins doesn’t seem to stir up a fraction of the emotion that the question of bird origins do, its potential implications for primate/human ancestry notwithstanding. Go figure.

  30. #30 Tiktaalik
    July 18, 2009

    “Speaking of mummification (what? this), mounting a small corpse in the grill of your car works well if you drive much. I had a small bird lodged next to my headlight, with its little feet sticking out, for … well, two years, I think, in the early ’90s. It looked almost as good coming out as it must have done going in.”
    Speaking of that, there used to be a mummified (and squashed flat) smallish frog stuck in the gap between the body of my car and the passenger door. I don’t know how it got in there, or how long ago (the car’s pretty old, so it could potentially have been there for years). It’s mostly disintegrated now though…

  31. #31 David Marjanović
    July 19, 2009

    The sense in which Hennig used “monophyletic” (an ancestor and all its descendants) is in fact older than that used by the “evolutionary systematists” (an ancestor and any number of descendants). This goes so far that the German word for clade is Monophylum.

    The ichthyosaurs are famous for their humongous eyes, suggesting that they used them instead of echolocation. Compare cephalopods and Janjucetus. Within the mosasaurs, the ichthyosaur-like Plotosaurus also has larger eyes than usual.

  32. #32 Ed Pardo
    July 22, 2009

    Something I remember from Chris Beard’s book “The Hunt for the Dawn Monkey” that he explained that the smallest mammals are insectivorous but similar animals larger are either carnivorous or herbivorous (in the explanation of earliest primates). If this apparently rule does this not explain fruit bats?

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