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Controversies from the world of ratite and tinamou evolution (part I)

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


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As blasphemous and offensive as it seems to say it, birds are pretty samey. Generally speaking, they’re small flying things with long forelimbs, proportionally large heads with big, globular braincases, and grasping feet where an enlarged first toe (the hallux) opposes the remaining three. A shape like this was – so both the fossil record and inferences made from cladograms show us – ancestral for modern birds, so any bird that deviates from it is weird indeed. Cue ratites. Gigantic, long-legged, flightless birds with proportionally small heads, short, ridiculously short, or absent wings, they are the closest that any bird group comes to recapturing the body form (and presumably lifestyle) of non-bird dinosaurs.

Palaeognath montage, featuring members of all recent lineages: ostriches, rheas, kiwi, emus, tinamous, moa, elephant birds, and cassowaries. Image by Darren Naish.

Conventionally, the term ‘ratite’ is used for the kiwi-emu-rhea-ostrich clade (even though it always feels a bit weird to regard kiwi as ratites). The 11 or so recently extinct moa of New Zealand and the also recently extinct elephant birds or aepyornithids of Madagascar are also clearly members of this group, and then there are a handful of fossil groups as well. But there’s another modern group we have to consider here: the tinamous of South, Central and southern North America. All 40 or so species are small compared to ratites, capable of flight, and superficially galliform-like. They lack the anatomical specialisations that make ratites so remarkable, like an unkeeled, raft-like sternum, reduced, atrophied or absent forelimbs, proportionally long legs and neck, loose, ‘decomposed’ plumage, and so on.

Slaty-breasted tinamou (Crypturellus boucardi) of Mexico and Central America, as illustrated by Joseph Smit. Image in public domain.

However, despite the fact that they were often regarded as neognaths close to galliforms in the past, tinamous clearly share morphological and molecular characters with ratites. Together, both are united within Palaeognathae, the bird clade typically imagined to be anatomically (and perhaps behaviourally and ecologically) archaic compared to all other modern birds. Because I’m British, I call these birds palaeognaths (rather than ‘paleognaths’), and this makes sense given that the group is termed Palaeognathae, not ‘Paleognathae’.

Neognathous palate at left; palaeognathous palate at right. I'll explain what's going on here some other time. Image from Naish (2012).

Palaeognathae means ‘ancient jaws’, this being a reference to the idea that palaeognaths have an archaic palatal structure compared to the other modern birds, the neognaths. Anyone well-read on bird anatomy or the history of bird classification will be extremely familiar with the idea that modern birds can be divided into those with a ‘palaeognathous palate’ versus those with a ‘neognathous palate’, but it’s always been a source of frustration to me that this distinction is never well explained. I’m going to add to that frustration right now by not explaining it here, either, but I promise that I will do so in the near future.

Ratite distribution, or the ‘Cretaceous Kiwi Hypothesis’

One of the most curious things about ratites is that they’re widespread, with a distribution strongly tied to the Gondwanan continents (fossils from Eurasia notwithstanding). Modern ratites are all flightless, so their common ancestor was, so it’s been assumed, presumably flightless too (though… wait for the next article for much more on this issue). Seeing as Gondwana broke up during the Cretaceous, does the far-flung presence of big, flightless birds mean that they owe their distribution to overland dispersal and vicariance rather than overwater dispersal? Exactly this has been argued by several authors, most notably Joel Cracraft (1974, 2001), and it’s reminiscent of Thomas Huxley’s notion of 1867 that living ratites are but “waifs and strays” – the remnants of a once near-global radiation of species. [World map below by Hoshie.]

The distribution of palaeognaths today (or, in near-modern times, anyway). Those Middle Eastern and Asian ostriches are now extinct, as of course are elephant birds and moa. Map by Hoshie, icensed under Creative Commons Attribution-Share Alike 3.0 Unported license. Icons by Darren Naish.

Map of the Late Cretaceous world. If ratites owe their distribution to vicariance and/or the use of overland routes, there must already have been rhea ancestors on South America, and elephant bird ancestors on Indo-Madasgascar, by this time. This looks unlikely! Image by Ron Blakey, NAU Geology. Image licensed under Creative Commons Attribution-Share Alike 3.0 Unported license.

If ratites only moved around the world using terrestrial connections, their lineages must go back a long way. As in, well into the Late Cretaceous, at least. After all, you need moa and kiwi ancestors to move onto Zealandia before it breaks away from the eastern margin of Gondwana during the Late Cretaceous, elephant birds have to get onto Madagascar before it becomes an island during the Late Cretaceous and they have to get onto Indo-Madagascar before it became isolated during the Early Cretaceous, you need rheas to get into South America before it becomes an island in the Cenozoic, and so on and on. In other words, there must have been ‘Cretaceous kiwi’ and such, if this model is correct (though, strictly speaking, these birds would have been stem-members of the kiwi and other lineages, and not necessarily modern-looking species with all the unusual features we associate with their lineages).

Palaeotis weigelti from the middle Eocene of Germany: a long-legged palaeognath regarded variously as a crown-ratite or stem-ratite. More on fossil palaeognaths in the next article. Image by Ghedoghedo, licensed under Creative Commons Attribution-Share Alike 3.0 Unported license.

There are no fossil ratites anywhere near this old (the oldest, in fact, are from the Paleocene). As it happens, there are good reasons for thinking that palaeognaths were present in the Cretaceous (Lee et al. 2014), but even studies of this sort ‘only’ posit palaeognath origins at about 83 million years ago, plus they concern the origin of the lineage that led to both modern palaeognaths and the Paleogene lithornithids (a group of long-jawed, archaic flying palaeognaths), not to the origin of modern-type ratites. [Adjacent image by Ghedoghedo.]

In short, neither the fossil record nor the pattern of palaeognath or ratite phylogeny supports the idea that these birds were diversifying, or even in existence, at the times required for a vicariant explanation for their distribution. The conclusion from this? They’ve gotten to where they are more recently, (mostly) via overwater dispersal. So, did this “overwater dispersal” require rafting of the sort always predicted for terrestrial animals, or did they fly? We’ll come back to this issue in the next article…

Ratites as ‘overgrown chicks’

Is THIS what happens when you thyroidectomise a starling chick? It's not, but it would be neat if it was, wouldn't it? Image by Darren Naish.

Are the unusual features of ratites primitive characters that they’ve retained from earlier kinds of birds, or novelties that have arisen more recently, partly through paedomorphism or neoteny (the retention of juvenile features into adulthood)? The neoteny idea for ratite evolution was promoted by Gavin De Beer (1956) who argued that the ‘fluffy’ plumage, unfused cranial sutures and palaeognathous palates of ratites might all be due to neoteny. By removing the thyroid glands of developing starling, Dawson et al. (1994) were able to make experimental subjects express ratite-like features in their adult form. Dawson (1996) even suggested that ratite intelligence and their propensity to swallow inappropriate objects might be due to neoteny (after all, babies tend to be dumb and inquisitive). Molecular support for the neoteny hypothesis was published by Härlid & Arnason (1998) who used mtDNA data to show that ratites are deeply nested within neognaths. This result is almost certainly due to poor sampling, however, and other molecular studies show that it’s very unlikely to be correct.

Stuffed kiwi, and skeletons of moa Dinornis and Struthio, an ostrich. Do these animals really look like 'overgrown chicks'? There's no real reason to take that idea all that seriously. Image in public domain.

While the neoteny hypothesis has long been popular, and while it’s promoted in what (unfortunately) remains the only comprehensive volume on bird evolution (Feduccia 1996), it’s important to be very sceptical about it. Features like a modified skull and palate and loose, shaggy plumage might result from neoteny, but they could just as easily be the result of natural selection that doesn’t involve neoteny: a shaggy plumage and specific cranial configuration, for example, could be advantageous for several reasons and you don’t need to invoke reliance on a specific physiological process to account for it. In some animals, open and unfused cranial sutures appear to be retained because they’re advantageous as goes the dissipation of stresses or because they allow flexion at certain points (Rafferty et al. 2003), for example, while the idea that the ratite palate is neotenous is almost certainly completely erroneous (Bock 1963, Elzanowski 1989).

Ostrich skeleton (with inset image showing weird scapulocoracoid), and the live animal at right. Robust, accessory ossifications like those seen on the ostrich scapulocoracoid are not consistent with the neoteny hypothesis. Photos by Darren Naish.

In any case, cranial sutures aren’t unfused in all ratites, plus ratites aren’t neotenic in many aspects of anatomy: their skulls are proportionally tiny, not proportionally large, their leg bones are thick-boned and seemingly ‘over-designed’, not juvenile-like in form or proportion, and their pelvic girdles are both highly variable (contrary to the theoretical predictions of neoteny) and extremely well ossified, often with accessory structures not seen in other birds. Elzanowski (1989) argued that de Beer’s hypothesis of neoteny for ratites – enthusiastically promoted by Alan Feduccia (1996) and colleagues – was politically motivated as well as weakly supported. Since 1930, de Beer was leading a new ‘anti-recapitulationism school’ and hence was seemingly opposed to the idea that the ‘primitive’ characters seen in ratites might really be retentions from an earlier stage in evolution. Rather, he wanted them to be evolutionary novelties that had arisen from neognath-like ancestors.

Palaeognath montage again, this time with animals crowded in a whole lot more. Image by Darren Naish.

In short, while it’s true that some ratite features do recall those that arise in neognaths forced to become neotenous adults (Dawson et al. 1994), the idea that neoteny is an important driving force behind ratite evolution is problematic and probably false. Firstly, their supposed neotenic features are either primitive characters retained from earlier birds, or novelties that have arisen for good reason, just as they have done – convergently – in some flightless neognaths. Secondly, ratites clearly aren’t neotenic in several organ systems, nor overall, but more plausibly look ‘hypermorphic’ more than they do ‘paedomorphic’. Thirdly, the idea that ratites are neotenic was originally proposed to help support an agenda (de Beer’s anti-recapitulationism of the 1930s, 40s and 50s), and has been supported since by workers promoting another agenda – this time, the idea that ratites might have evolved independently from diverse neognath ancestors.

There’s lot more I want to say on ratites and other palaeognaths, and in the next article we’ll start by looking at the ‘ratite polyphyly’ hypothesis.

For previous Tet Zoo articles on ratites and neornithine bird evolution in general, see…

Refs – -

Bock, W. J. 1963. The cranial evidence for ratite affinities. Proceedings of the XIII International Ornithological Congress, 39-54.

Cracraft, J. 1974. Phylogeny and evolution of the ratite birds. Ibis 116, 494-521.

- . 2001. Avian evolution, Gondwana biogeography and the Cretaceous-Tertiary mass extinction event. Proceedings of the Royal Society of London B 268, 459-469.

Dawson, A. 1996. Neoteny and the thyroid in ratites. Reviews of Reproduction 1, 78-81.

- ., McNaughton, F. J., Goldsmith, A. R. & Dgen, A. A. 1994. Ratite-like neoteny induced by neonatal thyroidectomy of European starlings, Sturnus vulgaris. Journal of Zoology 232, 633-639.

De Beer, G. 1956. The evolution of ratites. Bulletin of the British Museum of Natural History (Zoology) 4, 59-70.

Elzanowski, A. 1989. Ontogeny and evolution of the ratites. In Ouellet, H. (ed) Acta XIX Congresseus Internationalis Ornithologici, volume 2. University of Ottawa Press (Ottawa), pp. 2037-2046.

Feduccia, A. 1996. The Origin and Evolution of Birds. Yale University Press, New Haven & London.

Härlid, A. & Arnason, U. 1999. Analyses of mitochondrial DNA nest ratite birds within the Neognathae: supporting a neotenous origin of ratite morphological characters. Proceedings of the Royal Society of London B 266, 305-309.

Lee, M. S. Y., Cau, A., Naish, D. & Dyke, G. J. 2014. Morphological clocks in paleontology, and a Mid-Cretaceous origin of crown Aves. Systematic Biology doi:10.1093/sysbio/syt110

Naish, D. 2012. Birds. In Brett-Surman, M. K., Holtz, T. R. & Farlow, J. O. (eds) The Complete Dinosaur (Second Edition). Indiana University Press (Bloomington & Indianapolis), pp. 379-423.

Rafferty, K. L., Herring, S. W. & Marshall, C. D. 2003. Biomechanics of the rostrum and the role of facial sutures. Journal of Morphology 257, 33-44.

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. Sebastian Marquez 1:12 pm 03/18/2014

    Ahh, ratites. I remember enthusiastically devouring the article on the old paleos site. Too many questions, I’ll just wait till the next in the series :)

    Link to this
  2. 2. naishd 1:17 pm 03/18/2014

    Yeah – I hope it’s obvious to any reader that all those issues about the position of tinamous relative to ratites (SPOILER: tinamous are likely NOT the ratite sister-group, instead the relationship is far more intimate) are covered in the next article, so I’d appreciate it if people hold of discussing that subject until then… In the meantime, there’s plenty of other stuff to talk about.

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  3. 3. Gigantala 1:48 pm 03/18/2014

    Palaeognathae is one of my favourite clade of tetrapods for a reason, and it’s rather sad how literature on these birds often doesn’t address points of interest, particularly in regards to unusual extinct forms like lithornithids or elephant birds. Spoilers: moa winglessness and sexual dimorphism sounds ordinary compared to them.

    Tinamous are now established as true ratites closely related to the kiwi + cassowary + emu clade (and moas? I keep hearing about Tinamidae being the sister clade to Dinornithidae, but I don’t get clear sources on this), which actually makes discussions on how these animals got around all the more interesting, as tinamous are among the least flight capable of still-volant birds.

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  4. 4. DavidMarjanovic 2:57 pm 03/18/2014

    Huh. The palatine contacts the interpterygoid vacuity in birds? And the subtemporal fenestra, too? …Oh, due to the loss of the ectopterygoid the suborbital fenestra has merged with the subtemporal one… still, the palatine participating in the margin of the interpterygoid vacuity is rare outside of temnospondyls, where this condition evolved again and again: only caecilians and (if their weird thing really is the palatine) frogs come to mind.

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  5. 5. BrianL 3:56 pm 03/18/2014

    Those are some mighty fine feathered elephant birds you have there! Do we actually know anything definitive about the extent and nature of the feathering of elephant birds? Also, will you discuss that most mysterious of Holocene ratites, *Mullerornis*?

    I admit I want to head desk whenever I see Cracrafts vicariance hypothesis pulled out to explain ratite distribution in recent publications. Dawkins’ ‘ The Ancestor’s Tale’ and Newton’s ‘The biogeography and speciation of birds’ come to mind here. Even worse when it is being used to calibrate phylogenetic trees. Thankfully, this seems to be getting rarer these days.

    Do you just argue against neoteny to explain flightlessness in ratites or do you also argue against neoteny to explain some flightlessness in birds.

    By the way, do European any zoos have tinamous? The closest I’ve come to seeing one was a deceased embryo in the ‘operation room’ exhibit in Rotterdam’s zoo. I’ve even seen a live kiwi and I’d like to at least have seen living members of all living palaeognath ‘families’.

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  6. 6. BrianL 3:58 pm 03/18/2014

    Sorry, I made some terrible typos and errors in my post. I humbly apologise for them.

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  7. 7. Jurassosaurus 4:21 pm 03/18/2014

    I don’t have a horse in this race either way but:

    Firstly, their supposed neotenic features are either primitive characters retained from earlier birds…

    If palaeognaths are neotenic then should we not expect them to exhibit features seen in earlier bird species? It’s weird that an anti-recapitulation movement would push so hard for the mode of evolution that shows recapitulation.

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  8. 8. Gigantala 4:26 pm 03/18/2014

    Do we actually know anything definitive about the extent and nature of the feathering of elephant birds?

    There is no evidence of integrument in vorompatras, though folk traditions seem to be the origin of the dark brown colouring you often see them depicted in.

    By the way, do European any zoos have tinamous?

    I do know of people selling Crested Tinamous (either Eudromia elegans or Eudromia formosa), but I don’t even know if that’s legal.

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  9. 9. Dartian 4:47 pm 03/18/2014

    Ha! I know the source of your cassowary image, Darren. ;) Speaking of which… Sorry, but I’m going to be Mr. Art Critic for a while and point out that the cassowary is too small compared to the other ratites, especially the rhea.

    Brian:
    do European any zoos have tinamous?

    Yes. Vogelpark Walsrode in Germany, for example, has several species. Tinamous even breed there.

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  10. 10. Tayo Bethel 5:06 pm 03/18/2014

    @Naishd:
    Does the info in these articles appear in your book chapter in the Complete Dinosaur? *I read that chapter again and again–it never, never gets old*. when it comes to rhattites, its impossible to run out of interesting things to talk about … giant size, reversed sexual dimorphism so extreme that sexes get classified as different species, male parental care, etc.

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  11. 11. Jerzy v. 3.0. 6:09 pm 03/18/2014

    Please write more about elephantbirds! There is heaps of information about moas, but almost nothing on Aepyornis and Mullerornis!

    Re: tinamous in zoos: they are not very popular although breed easily. For everything related to which animals are/are not in zoos in Europe, check zootierliste.de.

    More interesting are past attempts to introduce Red-winged Tinamou to Europe as a game bird!

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  12. 12. naishd 6:29 pm 03/18/2014

    Thanks to all for comments.

    Gigantala (comment # 3): yes, there are studies supporting a close relationship between moa and tinamous. Stay tuned for part II.

    DavidMarjanovic (comment # 4): yes, the loss of the ectopterygoid in birds means confluence of the suborbital and subtemporal fenestrae, plus the anteroposterior shortening and reduction of the pterygoid means, yes, involvement of the palatine in the interpterygoid fenestra. Remember that this evolved within birds, since the pterygoid is still long and keeping the palatine away from the midline in taxa like Archaeopteryx.

    BrianL (comment # 5): I’ll try and remember to comment on Mullerornis later. And, yes, I’ve been surprised by the persistence of the Cracraftian vicariance stuff too. As for neoteny – it might help explain some anatomical features in some flightless birds (of whatever lineage), but my main point is that it doesn’t offer a magical, tidy explanation for the whole of ratite anatomy.

    Jurassosaurus (comment # 7): you’re correct, the logic as goes anti-recapitulationism is weird. Regarding “If palaeognaths are neotenic then should we not expect them to exhibit features seen in earlier bird species?”: yes, if neoteny were at play, we would predict the expression of ‘primitive’ characters, but the expression of ‘primitive’ characters doesn’t demonstrate the presence of neoteny… members of a lineage might just be morphologically archaic.

    Dartian (comment # 9): you are absolutely right that the cassowary is too small – I had to cheat for reasons of overlap/composition in the montage. But, hey, maybe I wanted it to be one of the dwarf cassowaries (there are some especially small fossil ones from the Pliocene and Pleistocene).

    More responses later.

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  13. 13. Yodelling Cyclist 7:05 pm 03/18/2014

    Oh yeah, Aepyornithidae!

    About ten years ago I spent a couple of months kicking around south of Anakao in Madagascar, and I spent quite a while wandering in the spiny forest hoping to find vorompatra eggshells. (I think I was supposed to be building a school…or something….). Suffice to say: no luck. I was lucky enough to spot some Indopacific humpbacked dolphins being actively hunted by the locals. Which was fascinating, if gruesome.

    On the subject of ratites, will there be any discussion of Eremopezus? Of the ootaxa from the Canaries? Palaeotis and Remiornis? Why did no ratites go north in the Great American Interchange? How come the ratites survived the inundation of Zealandia when the mammals all died? Are there any Antarctic rattite records? Could the distribution of the ratites in oddplaces tell us about how Gastornis managed to show up across the northern hemisphere? Finally in my ramblings, if ratites pulled off this sort of weird distribution, why didn’t the phorusrhacoids?

    Looking forward to more big birds!

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  14. 14. Gigantala 7:42 pm 03/18/2014

    @Yodelling Christ:

    - Eremopezus is usually not considered a palaeognath based on it’s foot morphology, which is more similar to that of Neoaves. That said, I think this is silly as some lithornithids do have similar toe articulations (Pseudocrypturus, for example), though then again I’m still in the dark about the most recent review of the Eremopezus holotype, so there.

    - The ootaxa from the Canaries are generally regarded now as pseudodontorns?

    - Presumably for the same reasons many other south american endemics like macrauchenids didn’t: near anihilation in the Miocene/Pliocene boundary + lack of ability to pass through rainforests.

    - Rheidae appears to have at best been a rather unspeciose lineage, considering we have more tinamou remains than

    - La Meseta Formation supposedly has ratite remains.

    - Unlikely, as giant flightless Anseriformes co-existed with ratites multiple times (gastornithids and basal ostriches in Europe and Asia, dromornithids and casuariids in Australia, moas and kiwis and giant geese on New Zealand).

    - Phorusrhacids occur in Africa and Europe for poorly understood reasons, while all ratite lineages seem extremely self contained, with all oceanic crossings having almost certainly been done by flight (with the possible exception of kiwis).

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  15. 15. Gigantala 7:51 pm 03/18/2014

    I wish I could edit the comment, to remove the “Rheiidae isn’t speciose” (spoilers: there’s more remains across the Cenozoic thsn I thought) and to clarify on what the New Zealand giant geese are (Cnemiornis spp.)

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  16. 16. Tayo Bethel 10:45 pm 03/18/2014

    what about raptor predation on rhattites? was New Zealand the only place where large raptors were a threat to rhattites?

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  17. 17. Dartian 11:27 pm 03/18/2014

    Darren:
    there are some especially small fossil ones from the Pliocene and Pleistocene

    Oh? Interesting! How small, exactly?

    Gigantala:
    Yodelling Christ

    I don’t know if that was a mistake or on purpose, but Jesus, what a mental image it makes! Thanks for the laugh! ;)

    Tayo:
    rhattites

    Ratites.

    Incidentally, speaking of ratites in Europe; since 2001, there is a small feral population of rheas in northern Germany.

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  18. 18. naishd 5:16 am 03/19/2014

    Re: small fossil cassowaries, Dartian asks “How small, exactly?”. To which I reply “Exactly the size of the one clearly depicted in my illustration, ha ha” :)

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  19. 19. Dartian 5:45 am 03/19/2014

    Hmph. Archosaur palaeontologists and their weird sense of humour…

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  20. 20. Mark Evans 5:53 am 03/19/2014

    @ DavidMarjanovic:
    The palatines also contact the interpterygoid vacuity in the basal plesiosaurian Anningasaura.

    Link to this
  21. 21. Gigantala 6:39 am 03/19/2014

    what about raptor predation on rhattites? was New Zealand the only place where large raptors were a threat to rhattites?

    Madagascar. Aepyornithids. Mahery eagle + unnamed Aquila species.

    Also, african eagles have been known to eat ostrich chicks, while the emu is an occasional target of the Wedge-Tail. New Guinea Harpy Eagles are also suspected of eating cassowaries, though this is at large mere speculation.

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  22. 22. DavidMarjanovic 7:34 am 03/19/2014

    Thanks for the explanations of palatal weirdness!

    Even worse when it is being used to calibrate phylogenetic trees.

    I remember that paper from 2001 which calibrated its tree by assuming that the moas must have walked to New Zealand in the middle of the Late Cretaceous… and then found that the kiwis must have arrived later anyway. Oops.

    How come the ratites survived the inundation of Zealandia when the mammals all died?

    The one known non-chiropteran mammal is from the Miocene, after the Oligocene inundation. *waffle* *waffle* climate, something – did in the crocodiles, too.

    Phorusrhacids occur in Africa and Europe

    …well, sorta kinda.

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  23. 23. Gigantala 10:09 am 03/19/2014

    I thought Lactavis and Eleutherornis were considered unambiguous terror birds? Their degree of convergence is supposedly so extreme that independently flightless Cariamae lineages have been dismissed.

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  24. 24. Gigantala 10:10 am 03/19/2014

    *Lavocatavis

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  25. 25. irenedelse 12:28 pm 03/19/2014

    Rheas are ratites, and rats are ratty. One H, one T. No H, two Ts.

    Er… Sorry for this nonsense. Must have been the TetZooPodcats drinking game… Ahem ;)

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  26. 26. Tayo Bethel 1:45 pm 03/19/2014

    Thanks for the reply .. and the correction :) New Zealand still seems to stand out as the only place where large rhatites were a significant part of any raptor’s diet. Watching a Haast eagle make a kill must have been an awesome sight to behold. Alas for the days of yore …

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  27. 27. Gigantala 2:45 pm 03/19/2014

    Depending, of course, on what were the favoured prey of malagasy eagles. The Mahery was probably a lemur specialist, as it’s modern relative hunts primarily primates, but the Aquila could have preyed primarily on elephant birds to avoid competition with the Mahery and the Giant Fossa.

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  28. 28. Tayo Bethel 6:11 pm 03/19/2014

    @Gigantala:
    Aquila eagles are well-known for preying primarily on mammals-. If the Aquila species was preying primarily on juvenile elephant birds it would be one of only a few cases I can think of of an Aquila eagle taking primarily avian prey. *Though to the eagle, a large terrestrial bird is probably as good as any mammal*

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  29. 29. Heteromeles 11:59 pm 03/19/2014

    Okay, I’m scratching my head. If tinamous are as good as rails at overwater dispersal, where are all the insular tinamous? Or am I missing something?

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  30. 30. Chabier G. 3:48 am 03/20/2014

    Heteromeles: maybe you are thinking on tinamous as the sister branch of all ratites, and thus inferring that the ur-palaeognath was a sort of tinamou. But, spoiling a bit, tinamous seem to be deeply rooted in the paleognath assemblage, so they are fairly derived (e.g. their hearth is strikingly small, less than 0’4% body weight compared to normal avian values of more than 1%), adapted to energy sparing terrestrial life, and they are incapable of long flights. The ancestral paleognath should be a good flyer, and very different from tinamous or extant ratites.

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  31. 31. Jerzy v. 3.0. 4:53 am 03/20/2014

    If ratities convergently evolved flightnesses six times, there should be lots of small differences in their adaptations. How legs operate during running (granted, moa and kiwi didn’t run fast), how feathers became fluffy, how wings are reduced, how ontology changed…

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  32. 32. naishd 5:13 am 03/20/2014

    Thanks for all the interesting comments. Heteromeles (comment # 29): who said that tinamous are good over-water dispersers? (Chabier G’s comment # 30 is pretty much on the money). Jerzy (comment # 31): “there should be lots of small differences in their adaptations”. And there are, but you knew this, right? It’s all in the next article.

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  33. 33. Gigantala 6:06 am 03/20/2014

    If lithornithids are a paraphyletic assemblage as often suspected, then they should be the models for the ancestors of ostriches,rheas, kiwis, emus+cassowaries and elephant birds, since they are seemingly very capable flyers. Tinamous seem to be a recently terrestrial lineage.

    Also, flightless ratites do clearly differ in many aspects from each other, from plumage to the development of their wings. The wing anatomy of ostriches and australasian ratites, for example, is radically different, with the former being bizarre fan-like structures with powerful claws, while the latter have very vestigial appendages that often lack remiges.

    Link to this
  34. 34. naishd 6:34 am 03/20/2014

    Ok, be quiet now – you’re going over stuff covered at length in the next article…

    Link to this
  35. 35. Yodelling Cyclist 7:32 am 03/20/2014

    Thank you to those who have taken time to reply to my questions.

    Off topic, may I recommend:

    http://www.youtube.com/watch?v=6TQq317Qjqs&list=PLE5C051E20D553713

    This is a series of palaeontological/zoological lectures from the Royal Tyrrell Museum, and good fun. Warning: a good number are on fish, but there are many on various tetrapods, esoteric taphonomic processes and odd aspects of field biology (“Do owls randomly sample the local small mammal assemblage?”). I felt it might be of interest to the Tetzoo readership.

    All the best
    Yod

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  36. 36. Andreas Johansson 8:01 am 03/20/2014

    David wrote:
    The one known non-chiropteran mammal is from the Miocene, after the Oligocene inundation. *waffle* *waffle* climate, something – did in the crocodiles, too.

    Re the crocs, might Ice Age NZ simply have been too cold? It’s quite far south by the standards of crocodilian distribution – if I may trust WP’s distribution map, the southernmost crocodilians today are at the latitude of the North Island.

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  37. 37. DavidMarjanovic 8:30 am 03/20/2014

    I thought La[vo]c[a]tavis and Eleutherornis were considered unambiguous terror birds?

    I thought Eleutherornis was one of those “ratites” like Remiornis and Palaeotis? But I don’t even remember Lavocatavis except for its name. It’s possible I’ve overlooked, or even forgotten about, recent literature; do you have a reference?

    Re the crocs, might Ice Age NZ simply have been too cold?

    That’s what I was insinuating. :-) Obviously, this works less well on mammals, but it still works in some cases (primates and rhinos in North America…).

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  38. 38. Tayo Bethel 9:15 am 03/20/2014

    @Naishd:

    The next article cant comesoon enough. :)

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  39. 39. Dartian 10:23 am 03/20/2014

    Gigantala:
    it’s modern relative hunts primarily primates

    Not always (I assume you mean the crowned eagle). Primates form the majority of its diet only in rainforests. In more open savanna habitats, other prey (e.g., small antelopes, hyraxes) usually dominate.

    the Aquila could have preyed primarily on elephant birds

    “Primarily”? As in, an eagle weighing approximately 5 kg would primarily prey on an Aepyornis weighing approximately 400 kg? A two orders of magnitude-size difference between predator and prey? That’s about comparable to a leopard preying primarily on adult elephants.

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  40. 40. naishd 10:27 am 03/20/2014

    Eleutherornis (see comment # 37) was long supposed to be an Eocene ratite: Mayr (2009) said that it still required comparison with gastornithids, with the probable non-gastornithid ‘Diatrymacoeti (then of uncertain affinities), and even with pelagornithids. Since then, Angst et al. (2013) have argued that these remains – both E. helveticus and ‘Diatrymacoeti (now Eleutherornis coeti) are actually Old World phorusrhacids, as is Lavocatornis from the Eocene of Algeria.

    Refs – -

    Angst, D., Buffetaut, E., Lécuyer, C. & Amiot, R. 2013. “Terror Birds” (Phorusrhacidae) from the Eocene of Europe imply Trans-Tethys dispersal. PLoS ONE 8(11): e80357. doi:10.1371/journal.pone.0080357

    Mayr, G. 2009. Paleogene Fossil Birds. Springer, Berlin.

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  41. 41. Heteromeles 10:38 am 03/20/2014

    Re: tinamous as over-water dispersers. If ratite ancestor dispersed overwater and then gave rise to extant ratites, where are its insular descendants? That’s what I’m getting at.

    OBVIOUSLY tinamous aren’t on islands, but that’s a problem, isn’t it? The evidence may suggest that the common ancestor of tinamous and ratites was a strong flyer that looked nothing like any of the extant forms, especially since the extant forms look kind of like each other through convergence. Still, it would be a lot easier to buy if there were weird flightless birds on other micro-continental islands that could be linked to that ancestral ratite. I suppose the Kagu is a neognath?

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  42. 42. Yodelling Cyclist 10:52 am 03/20/2014

    So…if the proto-ratite is some ultra over ocean disperser, why is/aren’t it/its descendants just EVERYWHERE? This is sort of why I raised the other flightless birds for comparison. How did they disperse? If gastornithids didn’t have a terrestrial dispersal, did they have some equivalent super volant ancestor that went flightless everywhere? Terror birds as well?

    Are we sure ratites aren’t penguins? (kidding!)

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  43. 43. John Harshman 11:06 am 03/20/2014

    I was once attacked by a tinamou (Eudromia elegans if I recall, in the bird house at the Miller Park Zoo in Bloomington, Illinois. It ran up to me on the path through the “rain forest” and started pecking furiously at my shoe. No idea why, but perhaps I had transgressed the unwritten law.

    People have jumped through all manner of hoops to save the vicariance hypothesis. Perhaps the worst example in my experience is in Haddrath, O., and A. J. Baker. 2001. Complete mitochondrial DNA genome sequences of extinct birds: Ratite phylogenetics and the vicariance biogeography hypothesis. Proceedings of the Royal Society of London, Series B 268:939-945. But is that a matter for part 2?

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  44. 44. John Harshman 11:10 am 03/20/2014

    So…if the proto-ratite is some ultra over ocean disperser, why is/aren’t it/its descendants just EVERYWHERE?

    Nobody said “ultra”, and local extinction.

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  45. 45. Yodelling Cyclist 11:23 am 03/20/2014

    Fair point regarding “ultra”, and I retract the hyperbole with apologies. OK with the local extinction, that makes sense, but it seems a bit odd that volant palaeognaths are (waiting for contradiction) not abundant/absent from faunas in the northern hemisphere. This could just be a result of taphonomic bias against birds, I guess, but if the flying palaeognaths can reach NZ from Aus in the Miocene, where are they in the fossil record? If they’re good long range dispersers, why don’t we find them in more places? Wherever palaeognaths are found – with the big exception of tinamous – they seem to be interpreted as flightless.

    Gondwana dispersal seems to make more sense. Phorusrhacids in Africa make more sense that way.

    It’s hard not to be tempted to join the dots with the oddities of the marsupial invasion of Australia and other southern peculiarities. These things may all be parts of a bigger southern dispersal picture that is very hard to piece together. Or maybe I need to be locked in another synchrotron. Hard to say.

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  46. 46. Yodelling Cyclist 11:28 am 03/20/2014

    Now I have learned of Lithornithiformes. This is a good piece to put into the puzzle that really helps. If anyone is in this discussion, and does not know of them, I suggest that wikipedia should be consulted urgently on the matter.

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  47. 47. Heteromeles 11:31 am 03/20/2014

    @Harshman: Occam’s razor, anyone? I get the problem with the vicariance hypothesis. What I’m pointing out is that the overwater dispersal hypothesis says that there was an ancestral strong-flying paleognath (I’m a Yank, shoot me), that spread throughout the isolated continents of Post-Gondwana. On every larg-ish island/continent it colonized, it became flightless and generally grew huge for a bird. Presumably on every smaller island it reached (Seychelles, New Caledonia, volcanic islands, etc), it went extinct?

    That’s a bizarre story too. We’ve got things like rails, pigeons, shorebirds, ducks, and herons that did exactly the opposite. What’s so special about paleognaths that they can become ratites on the biggest islands and die out otherwise?

    I’d say that either story needs evidence to back it up.

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  48. 48. BrianL 11:55 am 03/20/2014

    @Heteromeles:
    This may sound like a cop-out, but do realise that unlike for, say, mammals, the fossil record for Paleocene-Pliocene birds tells us very little about anything other than the crudest outlines (except for penguins)and is more about isolated bones than about very complete remains that can be readily placed in fossil series or bushy trees. Extinct birds of any stripe slipping under the radar is to be expected since the fossil record is very patchy to begin with.

    For example, a few hypothetical conclusions we might draw if we only had fossils and no living birds to go on if they, for some reason, all went extinct at the end of Pliocene:
    - Secretary birds went extinct after the earliest Miocene.
    - Anseranatids went extinct after the Eocene.
    - Touracos went extinct in the early Oligocene.
    - Frogmouths and potoos were restricted to the Paleogene of Europe and North America.
    - Mesites, toucans, kagu, sunbittern, elephant birds, hamerkops and the vast majority of passerines never existed.
    All of those conclusions would of course be erroneous, yet are strongly suggested by the fossil record as we know it.

    As for lithornithids, these are fairly well represented among North America’s and Europe’s Paleogene avifauna so they actually show such birds to show up across the world. The likes of *Palaeotis* and *Remiornis* also fit your pattern of ratites showing up on various landmasses throughout the world. (It’s been suggested that ostriches evolved in Paleogene Asia, though that’s far less certain than some sources might claim.)

    You’re right in saying that one would expect such stem-ratites to also have colonised oceanic islands. However, the heyday of these birds was probably in the Paleogene. Oceanic islands around back then have presumably all disappeared or nearly so by now. This would of course drive any indigenous ratites to extinction, indeed leaving only those on the larger landmasses. Kiwi are presumably the last stem-ratites to have gone flightless. Last year, *Proapteryx* was described, a small and possibly volant kiwi from the early Miocene. This probably pinpoints the last possible occurence for volant non-tinamiid stem-ratites somewhere in the Oligocene or earliest Miocene. Given that most oceanic island endemics appear to have evolved afterwards, it seems perfectly possible for their environments to lack ratites. Stem-ratites had gone extinct, as had or soon would any of their descendants on oceanic islands. So all in all, I’d guess ratites were actually present on many oceanic islands in the past.

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  49. 49. Yodelling Cyclist 11:58 am 03/20/2014

    Well, dromornithids are ducks, plus as I keep saying, terror birds and gastornithids existed on continents, so ratitites aren’t quite unique. They’re just unique in their ability to endure the pleistocene.

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  50. 50. Heteromeles 12:18 pm 03/20/2014

    @BrianL: We’re still not away from the rail and duck problem yet. There are extinct flightless rails and ducks all over the world, but we’ve still got the flighted members of the group out doing the same nutty things that got them to islands in the first place.

    With ratites, we don’t. I think it’s great that there’s a flighted kiwi fossil out there, but even with the notoriously spotty fossil bird record, it’s bizarre that ratites lose the small, flighted parts of the clade and to keep the giant flightless parts of the clade. Aside from tinamous, ratites seem to be doing everything backwards from neognaths.

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  51. 51. John Harshman 12:18 pm 03/20/2014

    I can see how overwater dispersal might be unsatisfying. But vicariance, for the most part, doesn’t work here. It needs divergences that are mostly way too old. If there were any sort of decent fossil record for Antarctica, some of this might be better explained. A land connection between South America and Australia through Antarctica doesn’t seem out of the question through the early Oligocene, which might help a bit. Part 2?

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  52. 52. naishd 12:33 pm 03/20/2014

    One more thing to consider as goes “where are all the fossil flightless island-dwelling palaeognaths?”… err, Heteromeles – do you know how terrible the fossil record is for island-endemics, especially in the Paleogene and Upper Cretaceous? (the time when these animals would, hypothetically, have been dispersing) Answer: there’s essentially nothing. And this is because the fossils haven’t been preserved, or have been subducted or eroded or whatever, not because they definitely didn’t exist. The lack of data here is a big problem.

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  53. 53. Yodelling Cyclist 12:45 pm 03/20/2014

    Well, actually we do have them. The lithornithiformes are known from paleocene europe – which would have been a large archipelago at the time. Bingo, volant palaeognaths, right where they should be.

    I didn’t know about them two hours ago.

    @ John Harshman: Doesn’t the marsupoial dispersal tell us that this must be so anyway?

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  54. 54. Andreas Johansson 12:45 pm 03/20/2014

    If most/all palaeognath dispersals were volant, one is forced to wonder if there’s something systematic that makes palaeognaths more successful as as flightless forms than as flighted. May ancestral palaeognaths have already been tinamouously poor fliers, their dispersals being more due to timely storms or the like than to any “ultra-volancy”? Extremely non-volant mammals have managed transoceanic dispersal after all.

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  55. 55. BrianL 12:46 pm 03/20/2014

    @Heteromeles:
    I doubt the evolutionary trajectory of a flightless island rail and a continental ratite are that alike as you seem to imply.
    I could very well see there being evolutionary pressure for ratites to grow big: Most (with the likely exception of elephantbirds and pre-Pleistocene/*Harpagornis* moa. For kiwi, mekosuchines may have been a dangerous preposition.) evolved alongside very capable predatory mammals so that there might be pressure for a flightless bird to grow large, in order to avoid at least some predation. On top of that, they had the advantage of larger landmass and corresponding resources to allow this growth into larger birds. An oceanic island simply wouldn’t have the resources to grow flightless birds that large.
    Also, is it really that weird for a succesful Paleogene grade to have gone extinct after that epoch, leaving only a few, large, bizarre and very derived descendants? Certainly some mammals appear to have done the very same (proboscideans, I’m looking at you especially). With ratites, I’d say it’s a very comparable pattern, except this time the succesful Paleogene grade happened to be volant and able to spread worldwide thus leaving not one lineage of ‘monstrous’ descendants, but several.

    Also, neither modern flightless rails nor flightless ducks nor flightless pigeons nor flightless ibises have had the same amount of time to evolve into bizarre giants that ratites did, and certainly not in comparable continental settings where evolving in that direction is more likely. Neognaths are certainly capable of doing just that however: Gastornithids, dromornithids and phorushracids were bizarre giants, but they too were Paleogene continental creatures and not Neogene small island endemics.

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  56. 56. John Harshman 1:21 pm 03/20/2014

    <i?Doesn’t the marsupoial dispersal tell us that this must be so anyway?

    Presumably relating to an early Oligocene connection between South America and Australia? Yes, that’s where I got the idea from, specifically the work of John Kirsch. This one, for example:

    Kirsch, J. A. W., F.-J. Lapointe, and M. S. Springer. 1997. DNA-hybridisation studies of marsupials and their implications for metatherian classification. Australian Journal of Zoology 45:211-280.

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  57. 57. Heteromeles 1:25 pm 03/20/2014

    @Darren: New Zealand? New Caledonia? I’m actually quite aware of the plate tectonics of most oceanic islands.

    @BrianL: The problem is that rails and ducks are quite old lineages, and throughout the Cenozoic they have island hopped, produced flightless insular lineages that went extinct, and occasionally coughed up giant forms on continents or large islands. Ratites require special pleading, because all we see are the large flightless forms and not the widespread active dispersers nor their flightless insular descendents. I would expect to see one (if not both) in places like New Caledonia that have sat above water long enough to collect them.

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  58. 58. Gigantala 1:34 pm 03/20/2014

    I was going to bring up Lithornithiformes + basal ostriches and the fact that ratites reflect the same type of “only giant specialists worldwide remain” also seen with basal Anseriformes and other bird taxa, but I see that has already been done for me.

    As for large continental neognaths, add Eogruiidae to the list.

    “Primarily”? As in, an eagle weighing approximately 5 kg would primarily prey on an Aepyornis weighing approximately 400 kg? A two orders of magnitude-size difference between predator and prey? That’s about comparable to a leopard preying primarily on adult elephants.

    A) could have been a chick specialist, B) the smaller Mullerornis could have been primarily targetted, C) modern Aquila already target disproportionaly massive prey.

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  59. 59. naishd 1:37 pm 03/20/2014

    Heteromeles: yes, New Zealand and New Caledonia are ancient island landmasses (albeit part of the once much-larger Zealandia). My point is: where are their Paleogene fossil faunas? For various reasons, they’re unknown (in this particular case, we have nothing until the Miocene).

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  60. 60. Yodelling Cyclist 2:33 pm 03/20/2014

    Eogruiidae? Google is silent on this, please expand.

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  61. 61. Dartian 2:45 pm 03/20/2014

    Gigantala:
    modern Aquila already target disproportionaly massive prey

    Not all Aquila; it’s pretty much only the golden eagle and the wedge-tailed eagle that do it. Verreaux’s eagle mainly eats hyrax and the Spanish imperial eagle mainly eats rabbits – and the eastern imperial eagle, steppe eagle, tawny eagle, and all the other remaining Aquila species take rather modest-sized prey too.

    As for the golden and the wedge-tailed eagles; yes, they do occasionally take prey larger than themselves. But these eagles, too, primarily hunt smaller prey (prey that they can subdue without significant risk of injury for themselves, and that they can carry away after the kill and eat at some safe location).

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  62. 62. John Harshman 3:22 pm 03/20/2014

    Heteromeles, are you supporting vicariance? How is that a better explanation? Do you in fact want to suggest an explanation that fits the data better than overwater dispersal? Once you have eliminated the impossible, whatever remains…

    Kagu and sunbittern are sister taxa. Why do we have no record of the wide radiation whose remnants they must be? Grebes and flamingos are sister taxa why do we have (almost) no record of the wide radiation whose remnants they must be? The fossil record sucks, and present diversity is not a great guide to past diversity. You just have to get used to that.

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  63. 63. Yodelling Cyclist 4:10 pm 03/20/2014

    Hmm. Even those of us mourning Gondwana vicariance can probably draw solace from the idea that Phorusrhacids may have pulled it off.

    Once again, cursing the lack of Palaeocene data from Australia.

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  64. 64. BrianL 4:11 pm 03/20/2014

    @Yodelling Cyclist:
    Eogruids (called ergilornithids in some sources) were a clade of large, likely flightless gruiforms (sensu stricto) that were present from the Eocene-Pliocene in Eurasia and which apparently were highly convergent with modern ostriches, to the point of their most derived representatives (*Amphipelargus*, IIRC) being didactyl. They have even been considered possible ostrich ancestors by some earlier workers, I believe. They indeed lack much of an internet presence, despite being a group of giant birds that evolved alongside the likes of *Sarkastodon*, entelodonts, mesonychids and indricotheres and lasting much longer than any of those did.

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  65. 65. Heteromeles 4:31 pm 03/20/2014

    No, I’m not supporting vicariance necessarily. My preferred logic system is four-sided, not two sided.

    Two sided logic is “If given two choices, A and B, one of them has to be correct. If A is not correct, then B has to be.” Four-sided logic says, if given two choices, A and B, then A can be correct, B can be correct, both A and B can be correct, or neither A nor B are correct.”

    I agree that the evidence for vicariance sucks. What I’m trying to point out is that the evidence for dispersal sucks almost as badly. The problem is that, when you’re caught in the binary logic of that stupid Sherlock Holmes quote, you can very badly mislead yourself into assuming that evidence against vicariance necessarily means that dispersal is right.

    What does the evidence actually say? According to what I’ve seen here, probably not vicariance, but that’s as far as it goes. That’s a very, very, long ways from saying that there’s a good case for dispersal alone. It could have been both vicariance and dispersal, or there may be something we’re missing that would help make sense of this.

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  66. 66. Yodelling Cyclist 5:14 pm 03/20/2014

    Thank you BrianL, very helpful.

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  67. 67. DavidMarjanovic 5:34 pm 03/20/2014

    Wow, so much traffic! :-)

    Angst et al. (2013)

    …Oh. Yeah. That. :-] I saw Angst’s presentation at a conference, but it hadn’t progressed as far as the paper, and I’ve missed the paper.

    Well, dromornithids are ducks

    …according to one or two tiny, tiny phylogenetic analyses.

    No, I don’t have a better idea what they might be. I’m just saying.

    New Zealand? New Caledonia? I’m actually quite aware of the plate tectonics of most oceanic islands.

    NZ has no known terrestrial fossil record between the Maastrichtian and the Pleistocene except for St. Bathan’s (Miocene). New Caledonia has nothing at all before the Pleistocene, AFAIK.

    People have only begun to discover the terrestrial fossil record of Africa between the Cenomanian and the Paleocene… there used to be nothing, too!

    They have even been considered possible ostrich ancestors by some earlier workers, I believe.

    Yep. Even Feduccia (1996) wasn’t clear on whether he preferred that hypothesis.

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  68. 68. Yodelling Cyclist 5:37 pm 03/20/2014

    Well, dromornithids are ducks

    …according to one or two tiny, tiny phylogenetic analyses.

    No, I don’t have a better idea what they might be. I’m just saying.

    Thank you for the clarification. Neognaths, anyway, which was the main point I was trying to make.

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  69. 69. John Harshman 5:38 pm 03/20/2014

    The situation is binary in that there are only two possible causes. “Neither” is not a credible option unless you can think of a third. “Both” is technically a possibility. I’m sure there has been a certain amount of vicariance in paleognath (sic: USA! USA!) history. The question is whether their distribution through the southern continents (and a couple of islands) has much to do with it. The only vicariant events that could conceivably be of the proper age would be those within southern Gondwana (South America, Antarctica, Australia) in the earliest Oligocene or before. Conceivably, that might explain the split between rheas and the Australasian birds. I don’t think it can explain the split between tinamous and moas. It certainly can’t explain anything else. There being no third possibility, we must conclude that dispersal is the only choice to explain the gross patterns of distribution. Vicariance might explain the split between, e.g. emus and cassowaries. But not vicariance due to continental separation, which is what the hypothesis has always been about.

    I really don’t see any alternative to “dispersal alone”. If you do, please suggest it.

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  70. 70. vdinets 1:29 am 03/21/2014

    Just for the record, tinamous are present on two islands off Venezuela (Trinidad & Margarita). Each island has just one sp., suggesting (but, of course, not proving) rare dispersal events rather than use of land bridges. These dispersal events were probably very recent (the island birds aren’t even considered separate subspecies); ancient human introduction is also not impossible.

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  71. 71. Dartian 2:22 am 03/21/2014

    Vlad:
    tinamous are present on two islands off Venezuela (Trinidad & Margarita). Each island has just one sp., suggesting (but, of course, not proving) rare dispersal events rather than use of land bridges

    Huh? Trinidad certainly was connected with the South American continent as recently as during the (late) Pleistocene. And Isla Margarita surely too, as its fauna suggests: both islands have plenty of non-flying terrestrial animals, including mammals and amphibians. There is very little in the way of suggesting long faunal isolation on either island (i.e., there are very few endemic taxa; most species also occur on the South American mainland). Thus, the tinamous most likely walked to Trinidad and Isla Margarita, rather than flew there.

    the island birds aren’t even considered separate subspecies

    Actually, the Isla Margarita population of the red-legged tinamou is recognised as a separate subspecies, Crypturellus erythropus margaritae, by some ornithological authorities, such as The Howard and Moore Complete Checklist of the Birds of the World. (I make no judgement on the validity of this subspecific allocation.)

    ancient human introduction is also not impossible

    The little tinamou Crypturellus soui, the species present on Trinidad, is supposedly also found on the Pearl Islands off the coast of Panama. I don’t know anything about the biogeographical history of these islands, but Wikipedia claims that the tinamou has been introduced there by humans.

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  72. 72. vdinets 6:57 pm 03/21/2014

    Dartian: so we have zero island colonization events… impressive.

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  73. 73. John Scanlon FCD 6:38 am 03/22/2014

    John Harshman, lucky that tinamou didn’t nail your head to the floor.
    BrianL, anseranatids (even if they were extinct now) are known to have survived into the Miocene.
    Shouldn’t ratites be able to cross water barriers by rafting (on their sterna)? :)

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  74. 74. Dartian 9:25 am 03/22/2014

    Vlad:
    so we have zero island colonization events

    Don’t try to twist my words. I neither said nor implied that to be the case.

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  75. 75. John Scanlon FCD 11:03 am 03/22/2014

    John Harshman again: Regarding terrestrial fauna, I don’t think there’s any support for links between Australia and South America even close to the Oligocene. Of course there are bugger-all Oz fossils in the relevant interval except for Tingamarra (Murgon), but the most similar S-Am taxa to Murgon mammals and snakes are either Paleocene or Cretaceous. That Kirsch et al. paper doesn’t seem to suggest an Oligocene connection (?I don’t think I’d've missed that?). Do you know the chapter by Black et al. (2012) (link)? They accept palaeobathymetry evidence for ‘final separation’ at 35 Ma, but there don’t seem to be any faunal separations anything like that late.

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  76. 76. Gigantala 11:04 am 03/22/2014

    And, again, tinamous are only exemplary for moa ancestors at most. With the possibly paraphyletic very volant lithornithids + at least five distinct island colonisation events from the main ratite lineages, there isn’t much room for arguing that ratites had a gondwannan bias.

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  77. 77. vdinets 2:28 pm 03/22/2014

    Dartian: but that’s what seems to be the case. If Trinidad and Margarita were colonized via land bridges, and all other island populations were introduced, we have zero island colonization events. No tinamous anywhere else in the Caribbean, or on any of the islands around Latin America.

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  78. 78. Andreas Johansson 3:40 pm 03/22/2014

    Re ratites on islands, there’s cassowaries on Seram, which IIUC wasn’t ever connected to mainland New Guinea. Acc’d to WP it’s unclear whether they got there by themselves or were brought by humans.

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  79. 79. John Harshman 4:33 pm 03/22/2014

    John Scanlon:

    I’m taking my Oligocene notion purely from memory of Kirsch et al., so may have misremembered. But as I remember, it’s their calibration of the tree that requires a connection at 35ma. Did I remember wrong?

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  80. 80. Yodelling Cyclist 4:48 pm 03/22/2014

    Well, something I hadn’t appreciated until recently – cassowaries are actually “semi domesticated” by some groups.

    Go here

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  81. 81. BrianL 4:48 am 03/23/2014

    Why would we even expect tinamous to colonise islands and tell us something about the dispersive abilities of early palaeognaths? Tinamous are derived and extremely poor fliers. They may be the only volant palaeognaths, but they’re very poor models for ‘lithornithids’ in this area.

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  82. 82. Yodelling Cyclist 5:43 am 03/23/2014

    Off track, any idea why the lithornithids didn’t make it?

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  83. 83. Gigantala 7:30 am 03/23/2014

    Presumably due to what happened to many other bird clades that disappeared at the same time like european hummingbirds, laurasian sunbitterns, laurasian cariamiformes, pseudasturids, et cetera.

    Given that lithornithids may actually be a paraphyletic assemblage, one would infer they survived in Australia until relatively recently, given Proapteryx*. Relic aussie lithornithids would have probably met their demise due to the continent’s progressive drying in the late Miocene/Pliocene, though the cassowary + emu line was quite diverse at small sizes in the Pliocene and Pleistocene until humans arrived and offed them.

    *Since lithornithids are thought to have been probers with their long, slender bills, kiwis do probably offer a good living analogue for them, albeit flightless. Given that Proapteryx appearently could still fly, and lithornithids were probably not a natural clade to begin with, but many lines leading to the modern palaeognaths, would it be considered a “lithornithid grade palaeognath”?

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  84. 84. Dartian 7:57 am 03/23/2014

    Vlad:
    If Trinidad and Margarita were colonized via land bridges, and all other island populations were introduced, we have zero island colonization events. No tinamous anywhere else in the Caribbean, or on any of the islands around Latin America.

    Oh, you were only talking about tinamous. I thought you were referring to Trinidadean & Margaritan land vertebrates in general. Sorry, my misinterpretation.

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  85. 85. BrianL 9:47 am 03/23/2014

    @Gigantala:
    With sunbitterns, I assume you’re referring to messelornithids? I don’t think these are nowadays considered related to sunbitterns. In fact, eurypygiforms (meaning sunbittern and kagu) do not have a fossil record at all, unless adzebills belong with them and then only one stretching back to the Miocene.

    I think you’re right about *Proapteryx* though. An interesting question, I think, is when did casuariiforms go flightless? If kiwi are their sistergroup, these at least were still volant in the Oligocene or even Miocene. If I’m not mistaken, casuariiforms first appear in the late Oligocene with very derived *Emuarius*. Presumably they would have had a decent stretch of time of flightlessness behind them at that stage.

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  86. 86. Gigantala 9:59 am 03/23/2014

    Yes, I was. This should render Eurypygiformes as a true gondwannan clade, then.

    If the earliest Emuarius remains are Oligocene in age, then one could suppose that australian palaeognaths were a relatively diverse group in the mid-Cenozoic, including both the conservative “lithornithid grade” birds that would later produce kiwis and more classical ratites.

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  87. 87. vdinets 12:31 pm 03/23/2014

    BrianL: there seems to be a bit of variation in flying ability among tinamous, with southernmost species being capable of seasonal short-range migrations. Some other poor flyers have succeeded in long-range dispersal: there is an Odontophorid in Africa, for example (or are there any alternative explanations to its presence there?)

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  88. 88. John Scanlon FCD 1:37 pm 03/23/2014

    John H: Kirsch et al‘s DNA hybridization estimate for the S-Am vs Australia split (Dromiciops vs Diprotodontia) was 59.80 Ma (node 15 in Fig. 13 and Table 3). Near 35 Ma, there are things like Bilby vs other bandicoots, ringtails vs gliders, and the basal split among crown dasyurids. They don’t put confidence intervals on those numbers, and I doubt anyone will be using those methods much again (WikiP says hybridization is ‘still used to help identify bacteria’), but the estimates look pretty consistent with sequence-based stuff and fossils.
    35 Ma has also been used as the guesstimate for the emu-cassowary split (somebody even used it as a calibration point in one of the ratite-phylogeny analyses, which was very dodgy), and some of these may reflect an important vicariance event within Australia, possibly related to the east-west divergence in flora that Wallace emphasised in Island Life (good book!), as a result of the circumpolar current breakthrough, increased aridity etc.

    BrianL: Thanks for mentioning Proapteryx, I see that paper’s available online.

    Link to this
  89. 89. Jerzy v. 3.0. 7:51 am 03/24/2014

    @78
    Dwarf Cassowary is also prehistorically introduceed to New Britain.

    @83
    I thought the only ratites which saw humans coming to Australia were Casuarius and Dromaeus?

    @85
    Adzebills! With tons of research on moa, including mitochondrial genomes, why there is not more published on adzebills?

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  90. 90. BrianL 8:34 am 03/24/2014

    A tangentially related question: I know ostriches, emus, cassowaries and rheas are capable swimmers (thanks, Youtube, for confirming this), and I’ve read the same about kiwi, but does anyone know if tinamous also swim?

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  91. 91. Yodelling Cyclist 1:02 pm 03/24/2014

    Quickly! To the plunge tank! Someone bring me some tinamous!

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  92. 92. Gigantala 1:04 pm 03/24/2014

    I thought the only ratites which saw humans coming to Australia were Casuarius and Dromaeus?

    As explained before, smaller casuariids also run around (collectively called “dwarf cassowaries”)

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  93. 93. Jerzy v. 3.0. 5:02 am 03/25/2014

    Tinamous presumably swim (or rather float on calm water) like most birds do. But they lack endurance and fat reserves of long-distance migratory birds.

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  94. 94. THoltz 2:46 pm 03/25/2014

    By the way, the “ratites are neotenous” concept was used in the Larry Niven short story “Bird in the Hand”: http://alanchick.info/page6.html

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  95. 95. keesey@gmail.com 2:50 pm 03/25/2014

    Why is flightlessness so prevalent among palaegnathes* if it’s mostly convergent? What about them preconditions them to flightlessness more than neognathes? Is it an adaptation? Or are they missing a key neognathe adaptation that prevents them from flying as well?

    (Sorry if someone addressed this and I missed it.)

    * I may be American, but the taxon’s name is “Palaeognathae”. Let’s keep the “I” in “ICZN”!

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  96. 96. Gigantala 4:10 pm 03/25/2014

    Flight has also been lost multiple times in neognath birds like waterfowl and rails. In palaeognaths, its probably just notable because only the terrestrial clades remained, but the “lithornithid-grade palaeognaths” are generally clearly volant birds that may form a paraphyletic assemblage, suggesting that modern ratites are just remnants of an once much larger diversity of flying birds.

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  97. 97. Tayo Bethel 5:23 pm 03/25/2014

    An off-topic question… When did the big, globular braincase appear in birds, and why might it have evolved?

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  98. 98. Jerzy v. 3.0. 5:23 am 03/26/2014

    @94
    There is a meme floating around (perhaps not founded in real events) that the ostrich started the legend of the Roc, as it is was taken for a chick of presumably enormous flying bird.

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  99. 99. DavidMarjanovic 7:54 am 03/28/2014

    the earliest Emuarius remains

    The only Emuarius remains are some 25 Ma old.

    That calibration point of 35 Ma ago *epic facepalm* was derived by taking those 25 and guessing how long evolution might have taken to get to E. from the MRCA of emus and cassowaries. That’s spelled out in the paper.

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  100. 100. irenedelse 10:52 am 03/30/2014

    Still 99 comments only? Well, I have a question: the recently described Anzu, a.k.a. the “chicken from hell”, was about the size of an ostrich, if I’m not mistaken. But do we know if its way of life was similar, or if Anzu was more carnivorous, for instance? And how about its plumage? Published reconstructions show naked digits, but couldn’t it have had long feathers like today’s ratites?

    Inquiring minds want to know. At least my own does ;-)

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  101. 101. John Harshman 11:58 am 03/31/2014

    That calibration point of 35 Ma ago *epic facepalm* was derived by taking those 25 and guessing how long evolution might have taken to get to E. from the MRCA of emus and cassowaries. That’s spelled out in the paper.

    “the paper”?

    Anzu

    Presumably a herbivore or close to it, in line with most oviraptorosaurs. The absence of teeth is a clue. I don’t think any gastroliths were found, as in Caudipteryx.

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  102. 102. DavidMarjanovic 7:53 pm 03/31/2014

    And how about its plumage?

    Unknown.

    “the paper”?

    Can’t remember the reference, and don’t have it here in any case.

    The absence of teeth is a clue.

    Absence of teeth is absence of evidence. Sure, a carnivore wouldn’t lose its teeth, but a toothless lineage can become carnivorous.

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  103. 103. John Harshman 7:57 pm 03/31/2014

    Absence of teeth is absence of evidence. Sure, a carnivore wouldn’t lose its teeth, but a toothless lineage can become carnivorous.

    And indeed many have. But they get nice, hooked beaks, raptorial claws, and such. I don’t see any of that here.

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  104. 104. naishd 7:10 am 04/1/2014

    David says (commen # 99)…

    “The only Emuarius remains are some 25 Ma old.”

    Material referred to Emuarius has a long range: the oldest stuff is from the Upper Oligocene, and the youngest from the Upper Miocene. E. gidju spans the whole of this range, while E. guljaruba is currently restricted to the Upper Oligocene. More species are due to be named in the future, so I hear.

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  105. 105. DavidMarjanovic 6:23 am 04/3/2014

    Oh, OK. But still, upper Oligocene is much closer to 25 (indeed includes 25) than to 35 Ma.

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  106. 106. John Harshman 11:19 am 04/3/2014

    Where are you getting this 35ma from? It’s been mentioned previously only in connection with marsupials and bathymetry, but you seem to be attaching it to Emuarius, and I can’t see why.

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  107. 107. DavidMarjanovic 6:04 am 04/4/2014

    It’s the calibration date some people have used for the emu/cassowary divergence. It’s explicitly derived from the 25 Ma age of Emuarius plus a guess on how long evolution might have taken to get there.

    No, I don’t know how this passed peer review.

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  108. 108. John Harshman 11:33 am 04/4/2014

    Is this possibly from Haddrath & Baker 2001? I recall they did some weird things with calibration.

    Haddrath, O., and A. J. Baker. 2001. Complete mitochondrial DNA genome sequences of extinct birds: Ratite phylogenetics and the vicariance biogeography hypothesis. Proceedings of the Royal Society of London, Series B 268:939-945.

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  109. 109. DavidMarjanovic 7:30 am 04/5/2014

    Likely, yes; but I don’t remember, I don’t have the paper here, and I don’t have online access at home.

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  110. 110. John Scanlon FCD 10:59 pm 04/10/2014

    Haddrath & Baker 2001, p.941:
    “The nodes were calibrated internally using the fossil Emuarius gidju from Australia, which dates back to the late Oligocene, 25 million years (Myr) ago. This species, while appearing close to the common ancestor of the emu and the cassowaries, was clearly on the lineage leading to the emu and was included in the subfamily Dromaiinae (Boles 1992). As this fossil post-dates the divergence between the emu and the cassowaries, we added an estimate of 10Myr, so that their common ancestor was dated at 35Myr.”

    Another related paper recycles that calibration and includes a couple of other (probably better) ones as well:
    Paton T., Haddrath O., Baker A.J. 2002. Complete mitochondrial DNA genome sequences show that modern birds are not descended from transitional shorebirds. Proc. R. Soc. Lond. B. 269:839–846.

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  111. 111. John Harshman 1:20 am 04/16/2014

    Thanks. That paper had a number of weird assumptions.

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  112. 112. naishd 5:56 am 04/25/2014

    To anyone still checking this comment thread… I haven’t forgotten that I’ll be doing a ‘Part II’. Just having to be patient for reasons associated with a soon-to-appear technical paper…

    Link to this
  113. 113. CJFryer 5:29 am 05/23/2014

    Is it this one?

    http://dx.doi.org/10.1126/science.1251981

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  114. 114. naishd 5:32 am 05/23/2014

    Yes.

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  115. 115. josimo70 3:18 pm 05/23/2014

    1) Moas were huge and more diverse than kiwis.We could presume that proto-moas reached NZ before proto-kiwis, couldn’t we?
    2) Bourdon, Estelle; De Ricqles, Armand; Cubo, Jorge (2009). “A new Transantarctic relationship: morphological evidence for a Rheidae–Dromaiidae–Casuariidae clade (Aves, Palaeognathae, Ratitae)”. Zoological Journal of the Linnean Society 156 (3): 641–663. doi:10.1111/j.1096-3642.2008.00509.x A transantactic Rheiformes-Casuariiformes would be plausible and analogous to Marsupialia’s biogeography.

    Link to this

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