ISPN

[tmkeesey]

This topic has already been broached in this thread, but I wanted to give it a more specific home with an accompanying poll.
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T. Michael Keesey
Director of Technology, Exopolis, Inc.

[tmkeesey]

I should explain that Marjanovic's branch-based definition, presented at both past ISPN meetings, is to use an extant species as the internal specifier and about a dozen traditional non-avians (e.g. Deinonychus antirrhopus, Tyrannosaurus rex) as external specifiers. (Doubtless he can say more.)
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T. Michael Keesey
Director of Technology, Exopolis, Inc.

[leowsham]

Opting for a non-crown node, this being more the paleontologist's opinion, I suppose. Neornithes may be more fitting for the crown, at present.
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vivat scientia !!!

[tmkeesey]

I think Marjanovic's idea is more in line with the traditional content.

It was a paleontologist (Gauthier) who first suggested the crown clade definition, so paleontologists aren't unanimous on this. I would think neontologists would tend not to have a strong opinion, anyway, since it wouldn't matter much to them in any event.
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T. Michael Keesey
Director of Technology, Exopolis, Inc.

[leowsham]

[tmkeesey]

The definition says nothing about sister taxa, only about external specifiers. Not the same thing.

As I recall, Marjanovic's definition has some extant bird species internal and about a dozen non-avian species external. Notably, since Archaeopteryx is not part of the definition at all, if Archaeopteryx were to turn out to have more recent ancestry with some non-avian group (e.g., dromaeosaurids) than with extant avians, it would not be an avian. This is consistent with traditional usage, where Archaeopteryx has danced in and out of Aves over the decades (although mostly in, which is where most phylogenetic hypotheses would place it under Marjanovic's definition, anyway).
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T. Michael Keesey
Director of Technology, Exopolis, Inc.

[David Marjanović]

Right. I have (...I hope) so many external anchors that any proposal of dromaeosaurid paraphyly would not constitute a problem. I'll try to dig up the complete list tomorrow (I don't know it by heart).

Archie is not mentioned in the definition because, if we ever have to decide (a very real possibility, it seems), I'd rather have Archie out than (say) Velociraptor in. Apart from my own personal preferences, I think this is marginally more compatible with the majority of previous usage of the name Aves. Thus, if the topology presented in the description of the Thermopolis specimen of Archie is right, Archie is not a bird.

In case anyone wonders, I just voted for my proposal Now I just hope I'll ever find the time to publish it.

[ottscay]

I considered joining the boards again under a pseudonym so I could vote for David's proposal twice

In all seriousness, I think it's a horrible idea for any definition of Aves to be tied to Archaeopteryx. More on that hopeully in an upcoming paper...

[tmkeesey]

I voted for the crown group, but I also like David's idea. I think it depends on whether the crown group convention is widely followed or not. If it is, then Aves should be no exception. If not, then David's definition (or something along those lines) captures the traditional usage most sucessfully.

I predict that nobody will vote for the total group.
_________________
T. Michael Keesey
Director of Technology, Exopolis, Inc.

[leowsham]

[tmkeesey]

[David Marjanović]

Rather too many external anchors than too few! Even Feduccia would be able to use my definition.

You're right about Ornithes. I suppose people would have considered it a synonym of Aves (it's just Greek instead of Latin) and therefore only named compounds like Archaeornithes and Neornithes. However, if Aves does end up with a crown-group definition, I suggest to attach Ornithes to my definition. This way "birds" would stay attached to the closest possible approximation of the traditional concept.

I vehemently disagree that the vernacular term "birds" and the scientific name Aves could have separate meanings. There is no way that "birds" could instead be attached to Avialae or something. People will use them as synonyms, consciously or inconsciously. If Aves ends up with a crown-group definition, some people will inadvertently misuse it for a larger clade (that is, that of "birds"), others will spend their time educating people that Ichthyornis was not a bird*, and some will probably do both.

Mind you: I am not generalizing. This is a special case; there are just too many people out there who know Latin or Spanish or Portuguese. Problems of this kind will not arise for Hominidae (a name that doesn't correspond to a vernacular term), let alone Maniraptora (a name created under phylogenetic nomenclature, without any baggage of previous usage).

* We already have this in the crocodylomorph world -- remember the comments on the DML following the redescription of "Supercroc" (Sarcosuchus): "it's not a crocodile, it's a pholidosaur!".

[leowsham]

[tmkeesey]

[Nick Gardner]

Admittedly, I had preferred the node-based clade with both Archaeopteryx and modern birds, but after some consideration of the circumstances, I believe it would be wise to cast a vote in favor of David's proposed definition, and have done so accordingly.