Template talk:Sauropsida

Testudines

That's correct that Sauria includes only Archosauromorpha and Lepidosauromorpha, I meant that [Testudines + Helveticosaurus + Eusaurosphargis + Sauropterygia + Thalattosauria + Saurosphargidae] is either sister to Sauria (clade with Ichthyopterygia) or basal within the Lepidosauromorpha... Bickelmann e.a. (2009) based phylos usually find this something like this: (Ichthyopterygia + Hupehsuchia + Thalattosauria) + [Archosauromorpha + [Choristodera + [(Helveticosaurus + Sauropterygia) + (Testudines + Lepidosauriformes)]]. Li et al. (2011) recently found [(Testudines + Lepidosauriformes) + (Helveticosaurus + Eusaurosphargis + Sauropterygia + Thalattosauria + Saurosphargidae) + ?Ichthyopterygia]. However, most genetically based analyses suggest that Testudines is inside Archosauromorpha or even inside the crown Archosauria (rarely)... Rnnsh (talk) 17:02, 24 February 2013 (UTC)

Wouldn't that mean Bickelmann et al.'s phylogeny places Ichthyopterygia, Hupehsuchia, and Thalattosauria outside Sauria, as they are right now in the template? And Li et al. didn't include any archosauromorphs in their analysis, so it's impossible to tell whether or not these taxa fall within Sauria. They have Lepidosauromorpha, not Lepidosauriformes, as the sister taxon of all these other groups (although it's strange that Sauropterygia falls outside Lepidosauromorpha in their analysis). Smokeybjb (talk) 17:27, 24 February 2013 (UTC)

Yes, in Bickelmann et al.'s phylogeny, Ichthyopterygia, Hupehsuchia, and Thalattosauria are sister to Sauria, but it is one of many variations. In Evans 2009 and in Borsuk−Białynicka & Evans (2009), all of those taxa + Sauropterygia were found to be archosauromorphs but in different "combinations"... As for Li et al. (2011), they actually included the Prolacertiformes (what is this?), Trilophosaurus, Choristodera and Archosauriformes, but they showed (even in the supplement) only their sister taxon. I presume they would have figured Choristodera if it had been found within what I call Lepidosauromorpha. They probably used Lepidosauromorpha incorrectly as it is defined to be the sister of Archosauromorpha... Rnnsh (talk) 17:58, 24 February 2013 (UTC)

Ah, I should have looked at the supplement! Also, the definitions of Archosauromorpha and Lepidosauromorpha are a little odd since Archosauromorpha has been defined as both a stem-based and a node-based clade, in which case non-lepidosauromorph saurians aren't necessarily archosauromorphs. Also, Evans's and Borsuk−Białynicka's various findings seem to be based on the data matrix of Müller (2004) and don't show very strong support for the positions of Ichthyopterygia, Sauropterygia, and other problematic groups. I'll change the template to include them within Sauria, but I don't think there's enough evidence yet to classify them as either archosauromorphs or lepidosauromorphs. Smokeybjb (talk) 20:29, 24 February 2013 (UTC)

That's exactly my point. For some reason, it seems like there is nothing certain about the relations of non-lepidosauriform and non-archosauriform "saurians" so I think it's better to cover most of the recent opinions. Btw, Bickelmann et al. (2009) data matrix is also based on the data matrix of Müller (2004), and about other definitions of Archosauromorpha - I think that it makes more sense to follow the stem-based one, as do most researchers... Additionally, I think that the different turtle clades should be separated, but I'm not sure there is a consensus about the clade names yet. Rnnsh (talk) 21:05, 24 February 2013 (UTC)

So do you want to include turtles in this template? I think it would be a good idea to just put them under Archosauromorpha and not Lepidosauromorpha, since most morphologic studies (at least traditionally) have grouped them with parareptiles. I don't know much about relationships within Testudines/Chelonii, but you could make separate templates for each major clade (by the way, there's already a template called Template:Extinct turtles, but its not organized by phylogeny). Smokeybjb (talk) 22:18, 24 February 2013 (UTC)

No, it's probably better to put them under Archosauromorpha, as genetic studies are more reliable and stable... But, what name to use for the "stem" of turtles? Testudines usually describes the node that includes all living turtles, but see this. Testudinata is an apomorphy-based clade that units all tetrapods possessing a turtle shell, but under this definition it excludes the recently named Odontochelys. Chelonia/Chelonii is used sometimes as the "stem" (no formal definition), or as the alternative to the name of the order (all living turtles). Rnnsh (talk) 14:42, 25 February 2013 (UTC)

I'd go with either Chelonii or stem-Testudinata. Smokeybjb (talk) 21:27, 26 February 2013 (UTC)