Spurs and blades on the wings of jacanas, lapwings, sheathbills and archaeotrogonids (clubs, spurs, spikes and claws part II)



A little while back we looked at the claws, bony knobs and other structures present on the hands of certain palaeognaths, waterfowl and other birds. Time to look at more of this sort of stuff - I kind of got distracted by lapwing taxonomy, so this is all going on for a bit longer than expected, sorry. Anyway...

Charadriiformes - waders, gulls and relatives - are also notable in including species that possess spurs and other peculiar forelimb structures. At least three jacanas have spurs: the Northern jacana [shown in the adjacent image, from wikipedia] is named for this feature, being known scientifically as Jacana spinosa. In this species, the Wattled jacana J. jacana and Pheasant-tailed jacana Hydrophasianus chirurges, the spurs are sharp-tipped, conical structures located on the extensor process of the carpometacarpus. In Northern jacanas these spurs are between 7 and 10 mm long.

Other jacanas lack spurs, but have a peculiar radius that is flattened and heavy relative to the ulna, and possesses a long blade-like ridge along its leading edge. In life, this possesses a cornified covering. It's present in the African jacana Actophilornis africana, Madagascan jacana A. albinucha, Bronze-winged jacana Metopidius indicus and Comb-crested jacana Irediparra gallinacea. Both the spurs and radial blades are used in combat [the diagram below, from Rand (1954), shows (F) the radial blade of an African jacana and (in both G1 and G2) the carpal spur of a Northern jacana].


Jacanas are weird birds - not just because of their incredible toes and reversed sexual dimorphism, but also because they indulge in some very neat bits of behaviour. Northern, Wattled and Pheasant-tailed jacana chicks, for example, hide beneath the water surface when scared by predators, and use their short bills as snorkels (their nostrils are placed further anteriorly on the bill than is usual for charadriiforms. This is also true of some gallinules, inviting speculation that they indulge in this behaviour too). Bosque & Herrera (1999) report that they were surprised to discover some weird yellow flowers sticking out of the water on a Venezuelan floodplain: on examination, these proved to be the bills of juvenile jacanas.

Spurs are particularly common in plovers, especially in the members of Vanellinae (the lapwings and wattled plovers*). Rand (1954) reported prominent carpal spurs in the Southern lapwing Belonopterus chilensis, White-headed lapwing Vanellus albiceps, Javan lapwing V. macropterus, Masked lapwing V. miles, African wattled lapwing V. senegallus, Pied lapwing V. cayanus and, of course, in the Spur-winged lapwing V. spinosus, River lapwing (also called Spur-winged lapwing, confusingly) V. duvauceli and Blacksmith lapwing V. armatus.

* Having referred to these birds as plovers, I should note that they do not form a clade with other plovers (Charadriinae) in all studies (e.g., Strauch 1978, Chu 1995, Ericson et al. 2003), and consequently have sometimes been given 'family' status (as Vanellidae). Pluvialis never groups with other plovers, so Charadriidae of tradition is not monophyletic... (there's more to say here, because some workers have noted that a monophyletic Charadriidae - i.e., one that includes Pluvialis, lapwings and true plovers - can be retained, but only if haematopodids (oystercatchers) and recurvirostrids (stilts and avocets) are included within it. That seems weird and not particularly useful) [image below shows hand - with spur - of a Masked lapwing].


In most of these lapwing species, the spurs are between 8 and 12 mm long (up to 22 mm in female White-headed lapwings) and clearly visible in life. Do remember that the bony processes you're seeing in the diagrams and photos used here are enlarged in life by keratinous extensions.

Incidentally, lapwing taxonomy has been substantially revised since Austin Rand wrote his paper on avian carpal spurs (Rand 1954: consulted extensively in the preparation of these articles). The majority of modern authors include all lapwings in the genus Vanellus but Rand and his contemporaries recognised many lapwing genera: the species mentioned above were listed in Xiphidiopterus, Rogibyx, Lobibyx, Afribyx, Hoplopterus and Hoploxypterus by Rand (1954). Phylogenies that incorporate a good sampling of lapwing species tend to recover little resolution within the group (Thomas et al. 2004), but a few clades have emerged, including four that seem to correspond to Belonopterus, Hoplopterus, Lobibyx and Lobivanellus. Given that we're now using unranked nomenclatures, any clades can be named, so it's conceivable that these old names could come back into use if they're deemed useful (I'm currently reading Jonathan Losos's Lizards in an Evolutionary Tree: Ecology and Adaptive Radiation of Anoles, and he makes the same argument therein for anole clades contained within the 'genus' Anolis) [hand skeleton of Southern lapwing shown below, from Rand (1954)].


Some authors, I note, have already taken to using some of these 'old' generic names: Campbell (1979, 2002) and Cenizo & Agnolin (2007), for example, argued that Belonopterus is highly distinct compared to Vanellus and they hence reinstated the use of this name. While relatively big carpal spikes are present in the Southern lapwing, as mentioned above, they're present in other members of the Belonopterus lapwing group and are very evident in such fossil species as B. downsi from the Pleistocene of La Brea (Campbell 2002) [carpometacarpi of some Belonopterus species shown below, from Campbell (2002). The fossil species B. downsi is shown in D-F].


Going back (just briefly) to those old lapwing names, you'll note that some of them incorporate specific references to the wing armament. Both Hoplopterus and Hoploxypterus, for example, mean something like 'shield wing'.

Really short spurs (just a few mm long) are present in various others lapwings, including Long-toed lapwing V. crassirostris, Grey-headed lapwing V. cinereus, Red-wattled lapwing V. indicus and Andean lapwing B. resplendens (again, note that - when Rand was writing - these species were all given their own genera separate from Vanellus [Hemiparra, Microsarcops, Lobivanellus and Ptiloscelys, respectively], thereby artificially raising the count of spur-handed plover genera).


Besides jacanas and lapwings (and the waterfowl looked at in the previous article), spurs are also said to be present in the Antarctic sheathbills. I'd love to know what these look like, but I've been unable to find any illustrations depicting these organs in the literature [Snowy sheathbill Chionis alba shown here; photo by David M. Jensen, from wikipedia].

Finally for now, spurs are also present on the hands of a peculiar and poorly known group of fossil birds best known from the Eocene and Oligocene of Query in France: the archaeotrogonids (Eocene British specimens are also known). Archaeotrogonids were originally described as trogons but it now seems more likely that these short-legged, superficially nightjar-like insectivores are members (or close allies) of Strisores (the clade that includes 'caprimulgiforms' and apodiforms). As is the case in most other bird carpal spurs, the archaeotrogonid spur is a stout, pointed conical process that seems to be a modified extensor process. The function of these spurs is unknown, but - like the spurs of spur-winged waterfowl, jacanas and lapwings - they were probably used in combat and/or defence.

And that's still not all on this subject. Pigeons and ibises next.

Bird hand anatomy has been mentioned or discussed a few times previously on Tet Zoo. See...

Refs - -

Bosque, C. & Herrera, E. A. 1999. "Snorkeling" by the chicks of the Wattled jacana. The Wilson Bulletin 111, 262-265.

Campbell, K. E. 1979. The non-passerine Pleistocene avifauna of Talara Tar Seep, northwestern Perú. Life Science Contributions, Royal Ontario Museum 118, 1-203.

- . 2002. A new species of Late Pleistocene lapwing from Rancho La Brea, California. The Condor 104, 170-174.

Cenizo, M. M. & Agnolin, F. 2007. La presencia del género Belonopterus Reichenbach, 1852 (Aves, Charadriidae) en el Pleistoceno de Argentina, con la descripción de Belonopterus lilloi nov. sp. Rev. Mus. Argentino Cienc. Nat., n.s. 9, 41-47.

Chu, P. C. 1995. Phylogenetic reanalysis of Strauch's osteological data set for the Charadriiformes. The Condor 97, 174-196.

Ericson PG, Envall I, Irestedt M, & Norman JA (2003). Inter-familial relationships of the shorebirds (Aves: Charadriiformes) based on nuclear DNA sequence data. BMC evolutionary biology, 3 PMID: 12875664

Rand, A. L. 1954. On the spurs on birds' wings. The Wilson Bulletin 66, 127-134.

Strauch, J. G. 1978. The phylogeny of the Charadriiformes (Aves): a new estimate using the method of character compatibility analysis. Transaction of the Zoological Society of London 34, 263-345.

Thomas, G. H., Wills, M. A. & Székely, T. 2004. A supertree approach to shorebird phylogeny. BMC Evolutionary Biology 4: 28 doi:10.1186/1471-2148-4-28

More like this

some workers have noted that a monophyletic Charadriidae - i.e., one that includes Pluvialis, lapwings and true plovers - can be retained, but only if haematopodids (oystercatchers) and recurvirostrids (stilts and oystercatchers) are included within it. That seems weird and not particularly useful

Seems perfectly sensible to me. It still wouldn't be a particularly big family and it's a much better option than a whole bunch of tiny (nearly) single-genus families.

Yes, I am fully aware that 'family' is an arbitrary concept that doesn't really mean anything. Still, the tendency towards ever-shrinking bird families is something that tends to rather irritate me.

Huh, spoken like a true invertebrate worker :) I see your point, but people are always going to need to refer to oystercatchers and the stilt-avocet clade as distinct entities, so the more sensible thing (in my opinion) would be to stick with tradition. Other than referring to lapwings as Vanellidae (and some workers do this anyway), this wouldn't involve the creation of any new 'family-level' clades (Pluvialis doesn't need a 'family' as it's on its own: if it does, Pluvialidae MacGillivray, 1852 exists anyway).

[from Darren: sorry, delayed by spam-filter]

Timely posts, Darren, as they came out as I was reworking my ornithopod lecture for my Intro to Dinosaurs class, and was working in a brief discussion on hypothesized uses for the thumb spikes in ankylopollexians and wanted to use some of these avian spurs as examples! In case you're interested, I went looking for pictures of living birds with the spurs showing, but those are hard to find! In addition to the photo you had in your earlier post, I also found two pictures of the southern screamer, Chauna torquata, in flight with spurs showing quite clearly, but wasn't able to find photos of any spurred birds actually using the spurs in any form of combat (inter- or intraspecific). Any ideas?

Given that we can give any clade a name, even in a ranked system, I don't see much difference between oystercatchers being a subfamily or tribe within Charadriidae or being a family, perhaps within a superfamily Charadioidea. But in the interest of neatness, I'm with Christopher. It's also evolutionary fun to think of them as weird plovers, which is what they are.

By John Harshman (not verified) on 14 Jul 2010 #permalink

It's true that things aren't going this way though. I just saw an article by Allan Baker and Sérgio Pereira where Pluvialidae, Pluvianidae and Pluvianellidae are all recognised in addition to the traditional charadriiform 'families'. I totally agree that adopting an 'inclusive Charadriidae' is no different (in terms of topology and membership) from naming a new Pluvialis-charadriid-oystercatcher-recurvirostrid clade that's called Charadrioidea, or whatever... but, seriously, isn't it more sensible to stick with the taxonomy widely used everywhere else in the literature?

Hoplopterus = weapon-wing (hoplos = weapon)
Hoploxypterus = weapon-sharpwing (oxys = "sharp", later "sour, acid" - oxygen, "acid-producer")

By J. S. Lopes (not verified) on 14 Jul 2010 #permalink


One might opt for a principle of doing the least damage possible to traditional classification (while making groups monophyletic), but what are the operational criteria for that? Is it more damaging to submerge an old family or to erect a new one? Should we discourage redundant clades, like monogeneric or monotypic families? We can't stick with the taxonomy widely used everywhere else in the literature, becauses it supposes a paraphyletic Charadriidae. Baker & Pereira are suggesting one sort of change; I suggest the other sort. Which is more conservative?

Similarly, should we make a desperate effort to preserve Ramphastidae by erecting a bunch of new barbet families, or submerge it in Capitonidae? (I go for the latter.) And I have no idea what to do about Caprimulgiformes. Etc.

Now, I'm sure there will be great numbers of trees (or perhaps electrons) killed over these trivial issues. And I'm glad to participate by fanatically defending my position, as long as we all agree it's a bogus issue.

By John Harshman (not verified) on 14 Jul 2010 #permalink

A nice measure to test if a clade deserves to be a family or subfamily would be its age. Why a lot of mammal families began in the Late Miocene, and some birds families go back to Eocene or earlier? Charadriidae familial status was determiated by just superficial traits or not? Modern crocs are almost similar to Cretaceous relatives, but along the same timespan tupaia-like primates turned into men or gorillas.

By J.S. Lopes (not verified) on 14 Jul 2010 #permalink

That's a can of worms we probably don't want to open here. But ranking by age has been seriously proposed, by Avise & Johns, and seriously attempted for birds, by Sibley & Ahlquist. One problem would be the error bars on tree topology, fossil ages, mapping of fossils to nodes, etc. Also, superficiality is in the eye of the beholder, and who says modern crocs are "almost similar" to Cretaceous relatives?

Avise, J. C., and G. C. Johns. 1999. Proposal for a standardized temporal scheme of biological classification for extant species. Proceedings of the National Academy of Sciences 96:7358-7363.

Sibley, C. G., and J. A. Ahlquist. 1990. Phylogeny and classification of birds. Yale U. Press, New Haven.

By John Harshman (not verified) on 14 Jul 2010 #permalink

I should that Modern crocs are almost "similar" to some of their Cretaceous counterparts. I meant to say a superficial similarity, superficial, but enough to lead many paleontologists to classified some of these species in extant genera. But we don't need to go so far, consider to my example the many putative Eocene species of Crocodylus.
The "chronotaxonomic" solution has the pivotal problem that we need to know the exact age of a clade to name it, what is usually impossible, or at least, always a bit subjective.
Taxonomy is about Relationship, and relationship degrees could be stated only when we know the correct sequence of ancestors-descendants. I'm son of my father and grandson of my grandfather, these relations were not subjective, but when someone intends to consider me and father as a clade A, and my grandfather another lonely clade B, this not seems natural.

By J.S. Lopes (not verified) on 14 Jul 2010 #permalink

Further to J.S. Lopes's etymological observations (comment 5 above):
Xiphidiopteryx seems to be from Xiphius (sword), -idio- (diminutive suffixe) and pter: so, "with little swords on its wings". Nice.

By Allen Hazen (not verified) on 14 Jul 2010 #permalink

seriously, isn't it more sensible to stick with the taxonomy widely used everywhere else in the literature?

One way you lose two families, the other way you gain two families. So neither one is any more divergent from past nomenclature. Someone's already alluded to the Sibley & Monroe classification which included oystercatchers and stilts within Charadriidae.

On the taxonomy... as I think I've said before, research communities should decide democratically (somehow) which taxonomic scheme best suits them: the reason that I favour the retention of those traditional 'families' is that this scheme is presently very much favoured by the majority. Sibley & Monroe's revised taxonomy - where numerous 'families' or 'subfamilies' were downgraded to 'subfamilies' or 'tribes' or whatever - hasn't caught on; ornithologists have clearly not preferred it, even if the Sibleyesque proposals made phylogenetic sense (as John said, look how much ink was spilt over the toucans-are-barbets issue, and most texts STILL use something like a traditional phylogeny).

As for the "we will have to erect new monotaxic families" argument, I don't buy it - those 'new' little 'families' are redundant with respect to their constituent taxa and people shouldn't be erecting them. If Pluvialis stands alone in the phylogeny, we just plain don't need a Pluvialidae to house it, and likewise for the other oddballs in phylogeny. In the end, I'm generally happy to go with a majority view. I agree that 'sinking' Haematopididae and Recurvirostridae into Charadriidae makes sense, and emphasises the phylogeny, but I just don't see this as being a decision favoured by the majority.

That painting appears to be by Thorburn, but I can't think which book it could come from.

Can anyone identify it further? There is no information on the Wikipedia Commons site.

Belonopterus = belone "needle" + pteros "wing".

By J. S. Lopes (not verified) on 15 Jul 2010 #permalink

"we will have to erect new monotaxic families"

Only considering the extant species, but all monotaxic family will just the "tip of the iceberg" of older and larger clades.

By J. S. Lopes (not verified) on 15 Jul 2010 #permalink

I agree that 'sinking' Haematopididae and Recurvirostridae into Charadriidae makes sense, and emphasises the phylogeny, but I just don't see this as being a decision favoured by the majority.

I don't think the majority has registered any opinion yet. But of course that's how it works. Competing taxonomies survive as long as anyone uses them, and die when they aren't used. "Plethornithes" vs. "Neoaves", for example. (By the way, I see Kaiser uses "Plethaves". Is that some sort of attempt at compromise?)

As for little families, if you live by Linnean taxonomy, families are mandatory. If you don't, Charadriidae isn't a family, and you can easily have Recurvirostridae within Charadriidae. For sentimental reasons, I prefer to retain (arbitrarily) ranked taxa, families and orders at least. And so either Recurvirostridae goes, or Pluvialidae enters.

By John Harshman (not verified) on 15 Jul 2010 #permalink

Both Hoplopterus and Hoploxypterus, for example, mean something like 'shield wing'.


The Wiktionary entry for "hoplon" says:

1. tool, instrument
2. a ship's tackle, rope
3. instruments of war: arms, armour, weapon
4. specifically the large shield carried by hoplites
5. penis
6. a gymnastics exercise

I think I have to agree with #6

By Owlmirror (not verified) on 15 Jul 2010 #permalink


I mean, I agree with comment #6 that the definition 3 in the list above was probably intended.

I note that the full LSJ entry on á½Ïλον has an additional specific definition which seems appropriate:

â IV. of the arms possessed by animals for self-defence, â[Ïὸν á¼Î½Î¸ÏÏÏον] οá½Îº á¼ÏονÏα á½Ïλον ÏÏá½¸Ï Ïὴν á¼Î»ÎºÎ®Î½â Arist.PA687a25, cf.

By Owlmirror (not verified) on 15 Jul 2010 #permalink

Animals named 'hoplo-' something tend to be named after hoplon (Greek for weapon or shield), or hoplites (Greek for a foot-soldier who carries a hoplon). So, Hoplosaurus the dinosaur, for example, is perhaps best translated as 'shield lizard', and that's what I had in mind above. I think, however, that 'weapon wing' was indeed the intended derivation behind Hoplopterus, not 'shield wing'.

Pluvialis thing just illustrates the nonsense of cladistics. You arrive at clades which are useless for description - share nothing distinctive from the second clade except some obscure genetic markers.

Ecologists and birders need to know what are they talking about - some small drab forest thingy which eat insects or some colorful huge-billed thingy which will would extrect the smaller one from its hole and eat it for dinner.

BTW, Greeks apparently described that Spur-winged Plover cleaned teeth of crocodiles, and if the reptile was unthankful, the bird stung it in roof of the mouth until it opened again.

Neither cladistics nor phylogenetic nomenclature stop toucans existing, and it seems daft to be angry with phylogeneticists for showing that toucans are a subset of barbets (hardly surprising anyway in view of Semnornis and others). Nomenclature should reflect phylogeny - I know you've argued that this isn't useful, but it's a basic tenet of biological classification and it's wrong not to employ it.

As a simple and funny phylogenetic exercise, I've tried to fit original Systemma Naturae genera into a evolutionary frame, and results were a bit odd, but interesting:
The most basal of Linnean Mammalian orders would be FERAE, with Didelphis (opossum) splitting first, then a subsequent cluster with the "insectivores" Sorex (shrews and some small moles), Talpa (moles and golden mole)and Erinaceus (hedgehog); after the traditional "carnivores" Viverra (genet, civet, mongoose, coati), Mustela (weasels, otters, martens, wolverine), Canis (dog, wolf, jackal, hyena), Felis (felids),Ursus (bears, badger, racoon) and Phoca (seal, fur seal, walrus). The other orders, Glires, Primates, Belluae, Pecorae, Cete, Bruta, would have evolved from insectivore Ferae.

By J. S. Lopes (not verified) on 16 Jul 2010 #permalink

Well, then sunk tetrapods as subgenus of bacteria. :D

As for little families, if you live by Linnean taxonomy, families are mandatory.

AFAIK, only genera and species are really mandatory. The other ranks are only treated that way by tradition.

Pluvialis thing just illustrates the nonsense of cladistics.

Please stop confusing phylogenetics (science) and nomenclature (convention).

By David MarjanoviÄ (not verified) on 26 Jul 2010 #permalink

Hello, enjoying your post very much. I often guess things like why do birds vary so little in time?. Is there any chance they re-discover teeth?, and viviparism, terrestrial avian, obviously, and "hands"?. Like to know about these few offenders to the permanence rule.

Is there any chance they re-discover teeth?

In chickens at least, two of the genes for enamel proteins are broken, and the other two have not even been found so far.

Vivipary is probably impossible for archosaurs in general, because their embryos get their calcium from the eggshell, so there has to be a hard eggshell.

By David MarjanoviÄ (not verified) on 28 Jul 2010 #permalink

Thank you very much for your response and explanation, it is really interesting. I see, they have gone too far, although perhaps there is still room enough for another kind of variations in structures. (Reptilian look to me very creative among Vertebrates with two classes derivate). (I apologize both for my English, very stained, and my little knowledge of many zoology aspects).

@Owlmirror, #20. Is that something like 'man doesn't have weapons like/near to the elk/moose'? Can't be bothered digging up a dictionary... (and Greek was HOW many decades ago, sigh)

By David Houston (not verified) on 29 Jul 2010 #permalink

Viviparity has been considered impossible in archosaurs because of the need for a hard eggshell to store calcium for the embryos; so it was interesting to see in the recent paper by Young et al. on the evolution of Metriorynchoidea that some of these marine crocodiles had evolved a wider pelvis with the bones rearranged so they could have given birth to a larger offspring; they also had weak pectoral and pelvic girdles and hydrofoil shaped front limbs.
The authors suggest that they therefore had become viviparous.
This is backed up by the size increase in some of them, with Dakosaurus manselii having a 1.1m long skull; this parallels other marine reptiles which became very large when they no longer had to come ashore to give birth.


the recent paper by Young et al. on the evolution of Metriorynchoidea

Reference, please.

By David MarjanoviÄ (not verified) on 30 Jul 2010 #permalink

I assume LeeB is thinking of...

Young, M. T., Brusatte, S. L., Ruta, M. & Brandalise de Andrade, M. 2010. The evolution of Metriorhynchoidea (mesoeucrocodylia, thalattosuchia): an integrated approach using geometric morphometrics, analysis of disparity, and biomechanics. Zoological Journal of the Linnean Society 158, 801-859.

And, yes, I will be covering all that cool new metriorhynchoid research some time in the near future. Yet another new paper on the group is due to appear soon.

that was the paper I was referring to.
And is the new paper the one that is going to publish Torvoneustes?

Also I believe the paper on the Portomaggiore crocodile is going to be published soon.


I just noticed that Andrea Cau has a competition regarding the name of the Portomaggiore crocodile on the Therapoda blog.
It looks like it will be published very soon.


And, yes, I will be covering all that cool new metriorhynchoid research some time in the near future.

...happy happy joy joy...


That name sounds good...

It looks like it will be published very soon.

If the beast isn't even named yet, that means the manuscript which will contain the name will be submitted to a journal soon. Then it'll undergo peer review, which takes months, and the time between acceptance and publication is several months for most journals, too...

By David MarjanoviÄ (not verified) on 31 Jul 2010 #permalink

Oops. The manuscript will be published soon, and we're supposed to guess the name which the accepted ( = in press) manuscript already contains; therefore, the 3 people other than Andrea Cau and Federico Fanti who know the name aren't allowed to participate... We have a week. The one who comes closest wins.

By David MarjanoviÄ (not verified) on 31 Jul 2010 #permalink

The abstract of the paper on the portomaggiore crocodile can now be seen in the articles in press section of the journal Gondwana Research.


Hi all,

I'm going to publish a series of post on my blog regarding the new Italian metriorhynchid I studied with Federico Fanti. It's not the same metriorhynchid re-named by Andrade et al. (JVP in press) that some of you cited above, but a new form.

The preview-post about the history of the "Portomaggiore crocodile" before I decided to re-study it is here.

Unfortunately, few people partecipated to the "Guess the new metriorhynchid name"... :-(