Mammalia, Synapsida, & Class?

[Johonebesus]

I have read repeatedly that Reptilia is no longer accepted as a valid Class, the name being changed to Diapsida. Accordingly mammals are just one clade within Synapsida. From what I understand, the basic Linnaean structure isn't totally rejected by cladistics, just reorganized. However, I cannot find a clear answer on the taxonomic status of mammals. The articles I can find using the word Mammalia give it the rank Class, but the articles using Synapsida give that clade the rank of Class.

Is there a consensus on this matter? Is Mammalia a subclass, or Synapsida a superclass, or is the whole thing still a mess with "correct" usage depending on the tastes of the author or instructor?

[Alyrium Denryle]

I have read repeatedly that Reptilia is no longer accepted as a valid Class, the name being changed to Diapsida. Accordingly mammals are just one clade within Synapsida. From what I understand, the basic Linnaean structure isn't totally rejected by cladistics, just reorganized. However, I cannot find a clear answer on the taxonomic status of mammals. The articles I can find using the word Mammalia give it the rank Class, but the articles using Synapsida give that clade the rank of Class.

Is there a consensus on this matter? Is Mammalia a subclass, or Synapsida a superclass, or is the whole thing still a mess with "correct" usage depending on the tastes of the author or instructor?

It is up in the air. Reptilia is currently paraphyletic, with Aves being the clade that is left out in the cold. Aves needs to be done away with and subsumed into reptilia. Once that is done the messy business of figuring out what turtles are can occur. This is because skeletal evidence suggests that they are the anapsid sister clade to diapsida. However molecular evidence suggests that they lost temporal finestra secondarily. So turtles could be diapsids.

Mammals on the other hand, are just one clade within synapsida, the rest of that lineage being extinct.

[Johonebesus]

Right, I know all that; the question is about taxonomic classification. Is the Class to which we belong still called Mammalia, has it been renamed to Synapsida with Mammalia demoted to a sub-class, or is there no consensus on this question? The usage I can find online seems all over the place.

[Alyrium Denryle]

Right, I know all that; the question is about taxonomic classification. Is the Class to which we belong still called Mammalia, has it been renamed to Synapsida with Mammalia demoted to a sub-class, or is there no consensus on this question? The usage I can find online seems all over the place.

I am not sure on the consensus. Though Synapsida is correct, and any argumentation regarding keeping Mammalia as a class essentially consists of mammal taxonomists wanting to feel special, kinda like ornithologists and Aves

[CaptainChewbacca]

Last time I was paying attention to taxonomy, they put all the Kingdoms into three 'Domains'. After that I stopped caring.

[Broomstick]

More and more, I think we're heading towards a great re-ordering of the way we describe species. New knowledge is superseding old ways of thinking. I imagine there will kicking and screaming whether we stick with the old system or start using a new one.

[Surlethe]

I devoted a little bit of time to thinking about taxonomy last year; didn't get anywhere since I am not biologically well-informed, but one observation I did make is that in any empirically consistent taxonomy "species" can't be an equivalence class if you stick with the old definition of "X & Y are in the same species if X will interbreed with Y in the wild". The best idea I could come up with on describing the animal kingdom - without resorting to unworkable "points in the space of possible genes" ideas - was to classify a "distance" between any two animals based on how far in the past they had a common ancestor. This would permit consistent mathematical descriptions in the continuous limit by treating biological populations as metric spaces (maybe even a manifold?).

[CaptainChewbacca]

The way things are starting to go now is how genetically similar or dissimilar organisms are, and group them that way.

[Alyrium Denryle]

I devoted a little bit of time to thinking about taxonomy last year; didn't get anywhere since I am not biologically well-informed, but one observation I did make is that in any empirically consistent taxonomy "species" can't be an equivalence class if you stick with the old definition of "X & Y are in the same species if X will interbreed with Y in the wild". The best idea I could come up with on describing the animal kingdom - without resorting to unworkable "points in the space of possible genes" ideas - was to classify a "distance" between any two animals based on how far in the past they had a common ancestor. This would permit consistent mathematical descriptions in the continuous limit by treating biological populations as metric spaces (maybe even a manifold?).

That isnt really how it works operationally. A species is presently defined as a monophyletic clade the maintains its ecological and genetic integrity through space and time. IE are two populations clearly the same lineage, and will they stay cohesive?