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how well would ratites fare?
Topic Started: Jan 13 2017, 10:10 AM (2,002 Views)
deathmetalfan6 Jan 13 2017, 10:10 AM Post #1
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if you don't know what ratites are they are the large flightless birds. ostriches, emus, rheas, cassowaries, kiwis, and the extinct moas and elephant birds. when i first saw the future is wild i was very fascinated by the carakillers, the evolved form of the caracara. i think its really cool that a bird that once flew lost its wings and became a ground hunter. ratites have kinda gone the same path in real life, they had ancestors that flew but over time they became built for running and lost their ability to fly. the more endangered ratites like cassowaries probably won't do so hot but i can easily imagine the more common ratites like emus and rheas giving up their omnivorous diets and taking on the role of top predators if large mammal predators die out over time because they are very strong and fast birds. thats just my idea, what do you guys think?
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LittleLazyLass Jul 21 2017, 11:14 AM Post #16
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It was already demonstrated that pangolins are similar to xenarthrans only by homoplasies, long before modern molecular trees.

Funny you say that, since your claim that New Zealand palaeognaths are the outlier to all the rest was also dismissed in the more recent morphological trees, as far as I last heard.

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For a start molecular data does not even mean the same thing as genetic data, as many people seemt o think it does. If you look at the genetic data alone glires would be the most stemward of placentals.

Of course it's not just genetics, but for the sake of simplicity we don't really need to go into the specifics of how it all works.

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Anyone who understands philosophy will notice the circular reasoning in a statement like "That morphology was clearly advantageous for it to evolve; why could it not be selected for multiple times?"

Care to actually explain yourself here instead of just saying a given statement is obviously wrong?

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any paleontologist will hopefully spot the error in dismissing morphology-only phylogenies. I mean if bones and teeth can be discounted so easily, there would be no cladistic analyses of dinosaurs and the like. Without molecular data the trees will all be wrong anyway, correct?

Palaeontologists don't have the ability to perform molecular analysis; they have to work with what they have access to. Will we ever know with complete and utter certainty whether the Saurischia, Ornithoscelida, or Phytodinosauria models of dinosaur relationships is correct without molecular data? Probably not, but that doesn't mean we should just give and say it's all hopeless. Morphological trees don't always get everything right, but they're often in the right ballpark.

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Therefore there would still be no reason to assume any crown ratite ever flew better than a tinamou.

There's no reason to think they couldn't have been better fliers, seeing as the last common ancestor of a monophyletic lithornithidae and crown paleognaths must've been a capable flier, should evidence suggest we should consider such a possibility (like the kiwi + elephant bird clade does).

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Protapteryx was not flighted nor flightless as far as anyone can tell. [snip]

Nobody ever said the evidence for Proapteryx being flighted rested on its size alone, which is ironic as you called me out on making a stawman argument (which I didn't make; I was assuming that's what you referred to when you said the new trees made "zoogeographical nonsense"). Anyway, if it wasn't flighted it very recently became flightless. Therefore, if Apterygidae only became flightless in the Miocene, it stands to reason that they could well have been capable fliers during the Oligocene and/or Eocene.
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kusanagi Jul 21 2017, 12:33 PM Post #17
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Yes there is a reason to believe that no crown ratites flew better thaa tinamou, supposing the molecular data is correct in putting the tinamous within traditional Ratitae: phylogenetic bracketing. Any other argument is an appeal to an absence of evidence. Anatomically only the lithornithids show adaptations to either strong flight or perching, and the lithornithids are monophyletic and outside of the ratites even when tinamous are included. And yes this point is of zoogeographical importance because the dispersal capacity of tinamous is about equal to that of fully flightless birds. Only very few lineages of birds ever made it to colonise Western Indian Ocean Islands from Asia the way hypothetical aepyornithid ancestors are supposed to have crossed the ocean its not like colonising New Zealand from Australia. To endorse the molecular tree is to choose a particularly improbable disperal.
Edited by kusanagi, Jul 21 2017, 12:43 PM.
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kusanagi Jul 21 2017, 12:38 PM Post #18
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Jul 21 2017, 10:54 AM
It's not just size: Proapteryx had relatively thin hindlimb elements more comparable to those of flying birds than flightless species. Even if it was flightless, it had to have evolved from a then recent volant ancestor, which means volant non-tinamou ratites were around at least as recently as the early Miocene.
Hindlimb elements relate to terrestrial locomotion not to flightedness and all I cn find is that the hindlimbs of P. were slender whereas those of the kiwis are robust for their digging ehaviours. The hindlimbs were in fact compared specifically to a ground dwelling rail with a tendency to flightlessness, Gallirallus. The most obvious traces of flightlessness in birds will relate to the forelimb skeleton not the hindlimb. Flight in P. remains ambiguous.

deathmetalfan6: ratites are the opposite of caracras and seriema relatives as they have a small skull and a long neck among birds. A macrocarnivore would need a large skull with powerful jaw muscles. Some flightless neognath would probably do the job better but the frugivory of cassowaries might become a kind of springboard to increased carnivory as it as for duikers and certain primates, and perhaps some carnivorans. Don't forget the more generalised tinamous either of which Rhynchotus seeems particularly disposed to prey on small tetrapods.
Edited by kusanagi, Jul 21 2017, 12:49 PM.
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LittleLazyLass Jul 21 2017, 01:13 PM Post #19
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kusanagi
Jul 21 2017, 12:33 PM
Yes there is a reason to believe that no crown ratites flew better thaa tinamou, supposing the molecular data is correct in putting the tinamous within traditional Ratitae: phylogenetic bracketing. Any other argument is an appeal to an absence of evidence. Anatomically only the lithornithids show adaptations to either strong flight or perching, and the lithornithids are monophyletic and outside of the ratites even when tinamous are included. And yes this point is of zoogeographical importance because the dispersal capacity of tinamous is about equal to that of fully flightless birds. Only very few lineages of birds ever made it to colonise Western Indian Ocean Islands from Asia the way hypothetical aepyornithid ancestors are supposed to have crossed the ocean its not like colonising New Zealand from Australia. To endorse the molecular tree is to choose a particularly improbable disperal.
I simply don't see how biogeography can be considered above what the phylogenetic studies indicate. If evidence indicates ratites flew from South-East Asia to Madagascar, then we must be forced to accept that fact and embrace that things are more complicated than we used to think, not ignore the data because it makes things more complicated than we used to think. Is it possible we'll figure out in the future elephant birds aren't most closely related to kiwis? Perhaps. But right now that's exactly what the evidence points to, and there's no reason to doubt that because of fringe possibilities.
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kusanagi Jul 21 2017, 02:02 PM Post #20
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Jul 21 2017, 01:13 PM
kusanagi
Jul 21 2017, 12:33 PM
Yes there is a reason to believe that no crown ratites flew better thaa tinamou, supposing the molecular data is correct in putting the tinamous within traditional Ratitae: phylogenetic bracketing. Any other argument is an appeal to an absence of evidence. Anatomically only the lithornithids show adaptations to either strong flight or perching, and the lithornithids are monophyletic and outside of the ratites even when tinamous are included. And yes this point is of zoogeographical importance because the dispersal capacity of tinamous is about equal to that of fully flightless birds. Only very few lineages of birds ever made it to colonise Western Indian Ocean Islands from Asia the way hypothetical aepyornithid ancestors are supposed to have crossed the ocean its not like colonising New Zealand from Australia. To endorse the molecular tree is to choose a particularly improbable disperal.
I simply don't see how biogeography can be considered above what the phylogenetic studies indicate. If evidence indicates ratites flew from South-East Asia to Madagascar, then we must be forced to accept that fact and embrace that things are more complicated than we used to think, not ignore the data because it makes things more complicated than we used to think. Is it possible we'll figure out in the future elephant birds aren't most closely related to kiwis? Perhaps. But right now that's exactly what the evidence points to, and there's no reason to doubt that because of fringe possibilities.
All trees are not given truth but merely spewed out by computer algorhythms as an aid to testing hypotheses such as, for exampe, biogeography. The statistical results are nothing unless you think about the implications of trees recovered and yes, they can be errant. A cross-Indian Ocean dispersal of even tinamou-like ratites is implausible indeed when you thik about it whereas the use of morphological data is not a "fringe possibility" or such cladistic analyses would not appear in peer reviewed journals. It is a parallel line of evidence and if you are inferring things like lithorithids within ratites or elephant birds flying across the Indian Ocean then you are the one ignoring the bracketing in your own preferred tree. The only evidece I can think of for a flying ratite is that rheas have white meat like neognaths whereas other palaeognaths have red meat. OTOH I don't remember the exact significance of this but it is physiological and supposed to make rheas more efficient runnng birds.

https://academic.oup.com/zoolinnean/article-lookup/doi/10.1111/j.1096-3642.2008.00509.x

The most parsimonious tree presented above goes like (New Zealand + (Madagascar + (Africa + (Neotropics + Australia))))) and makes more biogeographical sense excluding questions of flight and even vicariance. Firstly New Zealand's bird fauna flew in from eastern Australia and to a lesser degree New Caledonia so the total group of New Zealand ratites must be assumed to have been present on Australia as well. If the LCA of ratites still flew or not is perhaps irrelevant since in the early Tertiary New Zealand was still joined to Australia. The large terrestrial fauna of Madagascar on the other hand arrived from mainland Africa in the Tertiary and the total group of aepyornithids will have been present in the Ethiopian realm at some point before the closure of Tethys. Ratites have a consistent presence upon all the southern continents today and possibly in Eocene Europe (Palaeotis, incertae sedis?) but there are none yet for the Nearctic. Particularly South America was joined all the way to Australia by Antarctica during the early Tertiary. So the presence of ratites on all southern continents would still be problematic yet no worse than a parallel conundrum, the presence of large cariamae in both Africa and South America. Alternative trees might be ((Madgascar + Africa) + (Neotropics + Australia)) or (Madagascar + (Australia + (Africa + Neotropics))) in which case the problem still stands of how ostrich-like ratites got to be on both Africa and SAm-Ant-Aus. The number of geographical problems is much reduced.
Edited by kusanagi, Jul 21 2017, 02:17 PM.
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LittleLazyLass Jul 21 2017, 02:16 PM Post #21
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All trees are not given truth but merely spewed out by computer algorhythms as an aid to testing hypotheses such as...

They're also not baseless assertions that you can ignore at your leisure. It's not a random mess of branches randomly plotted out, but a model that a computer forms when taking into account all of the data given to it. If the molecular trees are correct, the answer to aepyornithid biogeography is simple; members of the crown were indeed at one point capable of flying over the ocean. If the molecular trees are wrong, why? Why have these results been repeatably replicated? Why has it formed a consensus among bird workers? Where's the error in the coding leading to elephant birds being sister to apterygids?

The entire rest of your post is merely trying to fill in the gaps under the presumption that the molecular trees are wrong because they don't fit your biogeographical model.
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kusanagi Jul 21 2017, 03:31 PM Post #22
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Flight does not merely mean animals can then disperse anywhere in the world as though wing make animals except from the rules of zoogeography: yes, one reason the morphological tree is better is because the biogeographical model it implies is more parsimonious than yours. It is not a pre-existing idea I had, it simply makes more sense the way I describe geographically and anatomically. There are different probabilities of morphotypes and ecotypes evolving around the world which are why some of them are rarer than others. And ratites are among the few birds with a long neck and very small head among the birds, a clade notorious for taking things in the opposite direction. OTOH it probably evolved only three times in all the neognaths (swans, cranes and flamingos) but you think it happened in each ratite group? Obviously it is easier if the ostrich-likes are monophyletic, be their LCA volant or not.

You seem awfully like soomeone who read a few web pages, then poses as an expert. If you understood this discussion you would realise that apart from the Neotropical-Australia link I am not actually talking about vicariance, nor am I endorsing the LCA of ratites as flightless. Of course it would be nice to see Palaeotis added and she might change things but by now all that can be said has probably been said.
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Carlos Jul 21 2017, 03:32 PM Post #23
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@lithornithids as a monophyletic group: Actually, this too is currently uncertain. Assuming some european ratites are ostriches, we might recover some lithornithids as stem-ostriches.

@Praopteryx limbs: The Gallirallus species it was compared to was specifically volant, as opposed to the robust hindlimb elements of flightless rails.

Flightless birds by default tend to have significantly more robust hindlimbs since resources normally allocated to the wings can now be used to strength leg bones.

Proapteryx in generally remains HIGHLY unspecialised, especially compared to the already modern-looking Saint Bathans moas. It had to be a relatively recent arrival back then
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LittleLazyLass Jul 21 2017, 03:43 PM Post #24
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Flight does not merely mean animals can then disperse anywhere in the world as though wing make animals except from the rules of zoogeography

Of course it doesn't, something like a tinamou could never make the journey, but a more capable flier that could do it has to be in palaeognath ancestry somewhere; simply finding such forms lived more recently than we think isn't shocking.

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one reason the morphological tree is better is because the biogeographical model it implies is more parsimonious than yours.

Once again, a simply explained biogeography fluke does not supersede what the cladistic analysis states. The morphological similarities can be explained by a similar but convergent lifestyle, which also explains all the morphological dissimilarities. All you've done is completely ignored everything I said in my last post and dodged my points.

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There are different probabilities of morphotypes and ecotypes evolving around the world which are why some of them are rarer than others. And ratites are among the few birds with a long neck and very small head among the birds, a clade notorious for taking things in the opposite direction. OTOH it probably evolved only three times in all the neognaths (swans, cranes and flamingos) but you think it happened in each ratite group? Obviously it is easier if the ostrich-likes are monophyletic, be their LCA volant or not.

But you don't support vicariance, and so already admit the morphotype must've evolved more than once? Or was the ancestral flying ratite just an emu with wings to fly?

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You seem awfully like soomeone who read a few web pages, then poses as an expert.

Ad hominen, very productive.

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If you understood this discussion you would realise that apart from the Neotropical-Australia link I am not actually talking about vicariance, nor am I endorsing the LCA of ratites as flightless.

Another stawman; after you corrected me the first time on you not following the vicariance model, I only talked about the event of crossing the Indian ocean, the one you refute, and did not accuse you of following vicariance after you corrected me on it.

For that matter, could you explain in detail what your biogeography model is? How many times did flightlessness evolve as far as you are concerned?
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kusanagi Jul 21 2017, 04:01 PM Post #25
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OK it is my fault if I fail to communicate well in English. I am Persian-Peruvian.

Early palaeognaths seem to be already global with the monophyletic lithornithids in the northern continents and tinamous in the Neotropical realm. Ratites do seem to have an origin in Gondwana although the well preserved and understudied Palaeotis may complicate this pattern. Within crown ratites there is a divergence at the root between a clade in Sahul (ie. NZ) that becomes irrelevant, and the rest of them in Africa (including Madagascar) and the past continental land mass of South America plus Antarctica plus Australia. The clade Rheidae + Casuaridae had an African origin and crossed from South America to Australia around the same time the microbiotheres did. (How is less relevant than the fact that varied animals did follow this same route from Africa to South America.)

Yes the ancestral ostrich-like ratite may not impossibly have flown: I do not say it did, or that it didn't since its probably irrelevant if their sister group tinamous are poor dispersers and ratit dispersal can be explained without long distance flight. The caveat I cite is the repeated loss of flight in some bird groups such as rallids. Yes if it could fly the LCA of ostrich-type birds looked like a winged ratite; rheas are well within the size range of flying birds and some large flying birds such as bustards have a broadly similar morphotype excluding their skulls are much larger.
Edited by kusanagi, Jul 21 2017, 04:09 PM.
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Carlos Jul 21 2017, 04:16 PM Post #26
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Actually, a recent study posits a predominantly laurasian origin for ratites. Remember, the earliest flightless paleognaths occur in Europe.
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kusanagi Jul 21 2017, 04:32 PM Post #27
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JohnFaa
Jul 21 2017, 04:16 PM
Actually, a recent study posits a predominantly laurasian origin for ratites. Remember, the earliest flightless paleognaths occur in Europe.
The only such study I can think of is Dyke 2003 who included Palaeotis and found it just about the sister taxon to crown ratites, which is nice but a bit inconclusive. The palate and bill have a resemblance to the probing lithornithids it is true, but this might suggest a dietary difference from the living ratites. Excepting the kiwi all ratites are specialised for herbivory with a well developed hindgut for fermentation as in most herbivorous dinosaurs. Moas take this trend to an extreme with a skull convergent upon that of grouse for biting through woody stems. Palaeotis would be less specialised for herbivory and maybe not a ratite at all although it is a palaeognath.
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IIGSY Jul 21 2017, 04:35 PM Post #28
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kusanagi
Jul 21 2017, 09:01 AM
If you look at the genetic data alone glires would be the most stemward of placentals.
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kusanagi Jul 21 2017, 05:38 PM Post #29
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Jul 21 2017, 04:35 PM
kusanagi
Jul 21 2017, 09:01 AM
If you look at the genetic data alone glires would be the most stemward of placentals.
What do you mean by that?
Unweighted parsimony applied to DNA sequences suggests a Placentalia rooted in rodents, improbable as it sounds.
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Carlos Jul 21 2017, 05:49 PM Post #30
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kusanagi
Jul 21 2017, 04:32 PM
JohnFaa
Jul 21 2017, 04:16 PM
Actually, a recent study posits a predominantly laurasian origin for ratites. Remember, the earliest flightless paleognaths occur in Europe.
The only such study I can think of is Dyke 2003 who included Palaeotis and found it just about the sister taxon to crown ratites, which is nice but a bit inconclusive. The palate and bill have a resemblance to the probing lithornithids it is true, but this might suggest a dietary difference from the living ratites. Excepting the kiwi all ratites are specialised for herbivory with a well developed hindgut for fermentation as in most herbivorous dinosaurs. Moas take this trend to an extreme with a skull convergent upon that of grouse for biting through woody stems. Palaeotis would be less specialised for herbivory and maybe not a ratite at all although it is a palaeognath.
Yonezawa, T.; Segawa, T.; Mori, H.; Campos, P. F.; Hongoh, Y.; Endo, H.; Akiyoshi, A.; Kohno, N.; Nishida, S.; Wu, J.; Jin, H.; Adachi, J.; Kishino, H.; Kurokawa, K.; Nogi, Y.; Tanabe, H.; Mukoyama, H.; Yoshida, K.; Rasoamiaramanana, A.; Yamagishi, S.; Hayashi, Y.; Yoshida, A.; Koike, H.; Akishinonomiya, F.; Willerslev, E.; Hasegawa, M. (2016-12-15). "Phylogenomics and Morphology of Extinct Paleognaths Reveal the Origin and Evolution of the Ratites". Current Biology. 27 (1): 68–77. PMID 27989673. doi:10.1016/j.cub.2016.10.029.

Also, there are several other ratite remains in Europe besides Palaeotis, such as Remiornis and various unnamed remains in the Paleocene of France and the Iberian Peninsula.
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