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Re: Some thoughts on cladistics



> And even physicists use colors when they are not specifically talking
> about light properties. There are no wavelengthists around saying that
> nobody should ever use these color words, just because the borders are not
> clear.

That's because there are no borders, and none have ever been defined. There
has never been anyone who argued about whether light of a certain wavelength
is yellow or green. There have been, and still are, incredible lots of
people who discuss whether something is a mammal or a therapsid, or a bird
or a dinosaur.

> So the question is, are groupings not based on PT/cladistics useful? Quite
> sure they are, as some examples prove:
>
> -There is a book called "The complete dinosaur", not containing more than
> a few words about birds,

Too few words about birds IMHO.

> - Another book (the Dinosauria) contains a chapter on prosauropods without
> being sure what exactly their status is,

So they _can't_ arrange them cladistically :-)

> and another about hypsilophodonts
> and other forms intermediate between basal ornithischians and hadrosaurs,

Chapters are some sort of ranks. Treating all basal
ornithopods/ornithischians in one chapter rather than 30 is simply easier. A
classification doesn't have chapters, unlike a book about the classified
organisms.

> - this mailing list is not called "the non-avian dinosaur mailing list"

Look at all the excitement about Mesozoic birds (Details On!) and about the
gross phylogeny of Cenozoic ones on this list.

> So, although transitional forms exist and any line drawn is more or less
> arbitrary, it is nevertheless useful to draw the line somewhere.
> [...]
> although they would be very much aware of
> the fact that the line is as arbitrary as the line between yellow and
> green.

Lines between colors have never been drawn.

> After all, there are still people around doing ichtyology, which
> they should not, on cladistic grounds.

Sciences are like chapters.