Talk:Euthyneura

crown

 * Euthyneura are considered the crown group of Gastropoda.[2] [..] The Euthyneura are considered to be the most successful and diverse group of Gastropoda.[2] Within this taxon Gastropoda have reached their peak in species richness and ecological diversity.[2]

Is that even self-consistent? And isn't the rest over-redundant?

Calling Euthyneura the most successfull clade of gastropoda means it contains more diversity and larger populations than other clades of gastropoda. If other clades of gastropoda have any extant members at all, then by definition euthyneura cannot be the crown group of gastropoda. And if those other clades didn't still exist, we'd say that instead rather than needing to say (let alone repeating over and again) that euthyneura are the most successful.

Isn't heterobranchia closer to the crown group? Cesiumfrog (talk) 01:46, 16 October 2012 (UTC)


 * User:Cesiumfrog, thank you for your intriquing questions. I think, it is self-consistent. I think, that crown group means monophyletic. Therefore the sentence means, that Euthyneura are some group of gastropods that are monophyletic. - Heterobranchia is also monophyletic and therefore it is also crown group. I would say, that wording "closer to the crown group" is not used. But it is possible to say, for example, that "Heterobranchia is larger crown group than Euthyneura". - The third sentence just explains what is written in the second sentence. The term "most successful" means, that they did conquer marine, freshwater and land environments, while other groups of gastropods did not. It also means, that they have the largest number of species within gastropods. --Snek01 (talk) 22:41, 19 May 2017 (UTC)


 * In the past "crown group" often referred to a subgroup of a taxon that had higher diversity than other subgroups. But today crown group usually means the crown clade, the group that descends from the last common ancestor of all extant members of the group.  By that measure, Euthyneura isn't the crown group of Gastropoda.  Can we word this in a different way?  Or perhaps find a citation that has described it as a crown group historically? Cephal-odd (talk) 03:57, 10 December 2020 (UTC)