The water-walker, the rib-glider and the frill-neck are all cousins!

Update March 5, 2016 with the addition of the cladogram from the large reptile tree.

Some reptile oddballs
>do< nest together. In this case, the extant “Jesus” lizard, Basiliscus, the rib-glider, Draco, and the frill-neck, Chlamydosaurus now nest together in the large reptile tree.

Figure 1. Draco volans. Note the anterior maxillary fangs, and the antorbital fenestra between the lacrimal and prefrontal, traits shared with Chlamydosaurus (Fig 2).

Figure 1. Draco volans. Note the anterior maxillary fangs, and the antorbital fenestra between the lacrimal and prefrontal, traits shared with Chlamydosaurus (Fig 2).

Draco (Fig. 1) and Chlamydosaurus (Fig. 2) are particularly interesting
as both share anterior maxillary fangs and an antorbital fenestra between the prefrontal and jugal (rather than between the lacrimal and maxilla as in other taxa with an antorbital fenestra). A long list of shared character traits unites these two still quite different lizards.

Figure 2. Chlamydosaurus also has anterior maxillary fangs and an antorbital fenestra between the prefrontal and lacrimal, as in Draco (Fig.1).

Figure 2. Chlamydosaurus also has anterior maxillary fangs and an antorbital fenestra between the prefrontal and lacrimal, as in Draco (Fig.1).

Basiliscus
is (at this point in the proceedings) a sister to the last common ancestor. But with that parietal crest, it has definitely evolved apart from the above two taxa for a long time.

Figure 3. Basiliscus, the "Jesus" lizard, does not share as many traits as Draco and Chlamydosaurus do, but is related, given the short list of Iguanids currently employed.

Figure 3. Basiliscus, the “Jesus” lizard, does not share as many traits as Draco and Chlamydosaurus do, but is related, given the short list of Iguanids currently employed.

We’ve seen this before, 
where and when some odd little reptiles shared more traits with each other than with any other tested reptiles. Members of the Fenestrasauria (Cosesaurus, Kyrgyzsaurus, Sharovipteryx, Longisquama, and pterosaurs) also include bipeds with dorsal frills. One of them also glided with outstretched ribs and legs, although distinct from Draco. In Sharovipteryx, the hind legs were much longer than the ribs.

Figure addendum 1. Cladogram of the Iguania, the sister taxa of the Scleroglossa, both members of the clade Squamata, a subset of the clade Protosquamata, the sister taxon to the Tritosauria.

Figure addendum 1. Cladogram of the Iguania, the sister taxa of the Scleroglossa, both members of the clade Squamata, a subset of the clade Protosquamata, the sister taxon to the Tritosauria. Many more scleroglossans are shown in the large reptile tree at ReptileEvolution.com.

We don’t have 
close prehistoric relatives for Draco or Chlamydosaurus yet. So at this point the evolution of rib-gliding or frill-spreading is not yet a gradual demonstration. But the other shared traits are, to my knowledge, unique synapomorphies.

I will update the cladogram this weekend.

 

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16 thoughts on “The water-walker, the rib-glider and the frill-neck are all cousins!

  1. Hmmmm interesting.

    So ‘unusual bedfellows’ are not a red flag here. The lack of a gradual accumulation of traits is not an alarm bell and the incompleteness of the fossil record is a perfectly acceptable explanation for why we don’t see the transition.

    I seem to recall when I put these very arguments to you, you vehemently argued against them. But surely I must be mistaken.

  2. Hmmmm interesting.

    So you’re perfectly happy to accept these ‘strange bedfellows’? The lack of gradual accumulation of traits does not ring alarm bells? The incompleteness of the fossil record is a perfectly reasonable excuse for not being able to see the transitions?

    I seem to recall making these very arguments to you and you arguing vehemently against them. But surely I must be mistaken.

  3. Hmmm interesting

    So ‘unusual bedfellows’ are not red flags here? The insufficient fossil record is a perfectly acceptable explanation for the lack of the gradual accumulation of traits?

    I seem to remember making these very arguments to you and you responding that they weren’t valid. But surely I must be mistaken

    • Neil, I see some selective reading and observing on your part here. The skulls are nearly identical and distinct from all other iguanids. That the ribs don’t flare in one case or the hyoids are not quite so elongate in the other is a testament to their separate evolutionary paths. What I was saying is we don’t have yet a pre-Draco with ribs only half as long.

      • And again, the same arguments. On a parallel note, Sharovipteryx and pterosaurs don’t have similar arm lengths, but no other tested taxa (other than Longisquama) share so many traits. If you can find, in either case, more closely related taxa, please let us know. To your point, traditional trees nest parasuchians and pterosaurs together, Vancleavea and Erythrosuchus together, now THOSE are odd mismatches — with more closely related and already discovered taxa waiting to be included in analysis.

      • Actually I’m not disagreeing with you on the relationships of the taxa ;) I fully support the fact tat these threeare close relatives. I’m more concerned with the stunning hypocracy; the fact that you’re willing to accept the incompleteness of the fossil record as an explaination when *you* find dissimilar taxa nest together, but when others try you don’t accept it.

        (And stop asking me to suggest “more closely related taxa”. I have on numerous occasions, and given you the characters to test them. Every time you refuse on the grounds that it would be too much effort on your part).

        Also sorry for posting there times before. For some reason the first two times it did not appear on my phone. Feel free to delete the first two if you like

  4. Neil, since you agree that these three are indeed closely related, despite the autapomorphy of extended ribs in Draco (not a trait that is scored), then why cry ‘hypocrisy’? And why ask for more closely related taxa here, specifically? There is a break in your logic. In this case, one might not recognize the relationships of these three lizards based on a quick in vivo look, but detailed analysis shows the relationship clearly.

    On the other hand you know my arguments against nesting pterosaurs in the vicinity of archosaurs, of nesting turtles with Eunotosaurus or placodonts, of nesting mesosaurs with pareiasaurs, etc. etc.

    By the way, we’re over 660 taxa now with the same 228 characters lumping and splitting them with complete resolution. So, at present, no new characters are needed. Please suggest specific taxa, if you have any that you think will change the tree topology. I look forward to adding them to the tree.

    • I cry hypocracy for you using an argument that you previously told me was invalid. I did not ask you for more closely related taxa, I was making an ironic point that you had accepted the lack of intermediate forms in your tree, but kick up a fuss about everyone else’s. Again hypocracy

      And I’ve said it before and I’ll say it again. The fact that you have a fully resolved tree does not mean no more characters need to be added. No one who actually understood phylogenetic methodology would say that, and your own example a few posts ago showed it was simply not true (although you refused to acknowledge it and desperately tried to backpedal by quibbling on the word “handle”). Its is an nothing more than an unsubstantiated argument you trot out as an excuse to put in the barest minimum effort. (Also again hypocracy; you accuse others of not adding the taxa you suggest yet refuse to add the characters others suggest)

  5. Validity only comes from testing in phylogenetic analysis. In my experience you can’t invalidate a relationship by adding or subtracting a few characters, but you can by adding/ subtracting a few taxa. That two taxa appear to be ‘odd bedfellows’ should only encourage testing. If they test out as sisters, then they are sisters. That’s what I did. I tested them against 660 candidate taxa. There’s no hypocrisy here. If others do not add suggested taxa, that is where the problem arises. If I add multiple characters, every one of the 660 taxa has to be reexamined for those multiple traits. Good enough is good enough, Neil. I’ve looked at a few of the studies that had 1500 traits and when you look at the character distribution too often scores are only sprinkled, uninformative in analysis.

    • There are dozens of examples on the published literature of different character combinations and ammounts producing different relationships. In fact there is an entire class of methods devoted to examining how different character combinations can produce different relationships. Your constant harping in about how adding a few characters doesn’t make a difference is simply wrong. And given your refusal to add characters, as well as the shocking ignorance of basic phylogenetic methodology that you constantly show, I really wouldn’t say “in my experience” as if it was the final word.

      As for the example where you back peddled: when you devoted an entire post to showing how fewer characters can correctly resolve a larger number of taxa e.g. One character and four taxa, two characters and eight taxa etc. The entire post was on answer to my comments on resolution, and all the way through the talk was of gaining full resolution of the tree. I demonstrated that when so few characters were used there was not in fact full resolution; there were many, very wrong trees that were equally parsimonious when so few characters were used. On my pointing this out to you, you suddenly decided you weren’t interested in only getting a fully resolved tree, but in showing that fewer characters can “handle” more taxa. And when I asked what you meant by “handle” if not produce a single correct tree, you didn’t reply.

  6. THAT is backpedalling? No, Neil, that is trying to explain to you the purpose for the illustration, over and over as I recall. I see it did not sink in yet. I didn’t care about multiple trees or loss of resolution. I only cared about showing how relatively fewer characters can handle, yes handle relatively more taxa. I stood my original ground. No backpedaling. In the real world, where the large reptile tree mirrors actual evolutionary events, relatively fewer characters can lump and split (= handle) relatively more taxa. The software, yes, the software recovers a single tree. Your theory just does not hold up in the harsh light of reality. “My constant harping about how adding a few characters doesn’t make a difference is simply” right. Proven over and over and over again. Not sure what is happening with you if you can’t accept computer-generated, unbiased reality.

    • For the third time I will ask, what did you mean by handle if you didn’t mean produce a fully resolved tree?

  7. In the large reptile tree handle means able to lump and split all the taxa, as I wrote before. In the illustration, well, it was just an illustration. It could have been taxon A, B, and C, but I gave them names and real characters.

    • Even with that as your definition, I demonstrated the few characters could not ‘handle’ more taxa. It was not able to correctly lump and split taxa in your own illustrations.

      Read again the post where I do exactly what Paup does and count character changes on different trees. Those few characters were not able to lump the mosasaurs together, the mammals together, the whales together. It does not work and your own example showed it doesn’t, because parsimony does not lump taxa with a shared plesiomorphy.

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