Re: [dinosaur] Party like it's 1758!

[David Marjanovic <david.marjanovic@gmx.at>]

> > > ancestor of A and B" becomes a mess if A or B turns out not to belong to 
> > > that clade.
> >
> > I thought, by definition, that A and B had to be part of the clade.
>
> Sure, by definition, but what if A or B was misinterpreted and actually 
> belongs to some other group entirely..? That screws up the definition of the 
> new A+B group. Nor can reviewers be expected to catch everything.

That's what emendation is for (Articles 15.8 to 15.15).

> > In the research on Mesozoic dinosaurs, and much else of vertebrate 
> > paleontology, it is usually the genus rank that is applied to the smallest 
> > recognizable clades, and species names are an afterthought added to honor 
> > colleagues or make clever puns with.
>
> Many taxa (species) do have multiple individuals referred to them, so it's an 
> over-generalization to say dinosaur palaeontology treats genera as species.

No â not when the individuals can't be morphologically distinguished (at 
least beyond what the authors consider individual variation within a species). 
Again: the smallest recognizable clades are usually formalized as genera in 
vertebrate paleontology, with a few exceptions like Cenozoic mammals.

> There is a trend toward splitting these days, with some genera being 
> separated into multiple species. One reason there are so many monospecific 
> genera is that species differences in many cases are minor and hence not 
> recognized. Does that make sense?

Sense, yes, but it's not an accurate description of the situation in much of 
vertebrate paleontology, where:
1) most new species are automatically named as new genera as well;
2) fairly little splitting, or lumping for that matter, is currently going on;
3) of course it is always possible that the species we recognize from fossil 
bones each consist of several species that differed in soft anatomy, behavior 
or whatever. But that's an argument against recognizing species, and for just 
naming the smallest recognizable clades instead. Under the rank-based codes we 
can't do that, we must name species if we name anything at all.

> Btw, I'd be curious to know some of those clever specific puns. Some species 
> names are annoying, yes (as well as some genus names), but most are legit.

"Pun" was not a good choice of word for what I think I had in mind, e.g. 
spreading a phrase over the genus and the species name (*Yi qi* "wing strange", 
*Mei long* "soundly-sleeping dragon" in that order)...

> Yeah I know, if they can interbreed, then they're not distinct species (much 
> less genera).

Do the first-semester biology textbooks still use this particular species 
concept? Because hardly any taxonomists do.

> At a minimum, they are distinct, separately-evolving populations and need to 
> be accounted for in a phylogeny. Many populations that we thought were single 
> species are turning out to have multiple genetically-distinct subpopulations. 
> Dolphins, elephants, caimans, you name it. This means species or incipient 
> species.

This is actually a good argument for naming clades and species independently of 
each other.