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Re: Sauropodz r kewl WAS silly ramble



Am 17.04.2012 14:09, schrieb Jaime Headden:

 It was not my intention to be hostile, so the tone of the response I
 received from Mike seems particularly odd.

But apparently it wasn't sent to the list (I haven't received it), so there's probably no point in discussing it here...

 Consider that the commentary of this entire thread has been on the
 efficacy of certain names, especially referring to *Brachiosaurus* as
 an equivalence to *Brachiosaurus altithorax*, which in zoological
 terms would be just *B. altithorax* for the most part.

(Point taken, but even neontologists don't abbreviate genus names before they've spelled them out once.)

 [...] *Brachiosaurus*, being capitalized, it the primary element of
 the name, a fault I'd rather lay at the feet of Linnaeus than anyone
 else, but a typical effect in the classical language he was using.

It's not simply a side effect of the default word order of Latin; Linnaeus deliberately employed it because of his philosophy. To him, the genus really was the basic _general_ unit, and the species was _specific_. It was an additional subdivision diagnosed by "less important", less "general", more "specific" characters. The modern emphasis on species as units of biodiversity and genera as a biologically meaningless rank is much younger; Linnaeus thought that genera were real.

 and even the ICZN doesn't tolerate or regard anything higher than
 "family-level" ranks.

Not true. Most rules (such as priority) don't extend above the family group of ranks, but the use of higher ranks is not at all discouraged.

 Growing is the movement to abandon ranks, and their concordant
 problems. I've written on this on my blog ad nauseam, and of course
 many of the offenders have defended their choices, but all of them
 have and will continue to use "genus" without any care for its lack
 of scientific value. When Mike argues about what I'm talking about,
 his very message is ripe with the problem I speak of, his continuing
 demonstration that despite knowing a genus means nothing, _he's still
 using it_.

He's using a genus _name_ as a _clade name_. I really can't see why he shouldn't.

 When Mike says "[t]hey're just names on characteristic specimens",
 then he really doesn't understand the problem to its extreme:
 scientific nomenclature names the specimens as proxies for a set of
 organisms, but the "genus" and the "species" are completely different
 from the _specimens_,

The names are attached to the type specimens; the set of organisms consists of the type specimen and, in practice (at least in paleontology), all others that are similar enough to it.

 and intend to describe instead a set without any concordant value.
 _They have no intrinsic value_.

Please explain what you mean by "concordant value" and "intrinsic value".

 I similarly have no problem with a taxon named *Giraffatitan* or
 another named *Brachiosaurus*. What I have a problem with is people
 determining that a taxon named *brancai* MUST or SHOULD be divided
 from *altithorax* in a fixed fashion that can be comapred to other
 issues, like how to divide *Psittacosaurus* into neat, clean "genera"
 or whatever.

These two cases are the same as far as the ICZN is concerned, but not as far as the practice of the last few decades is concerned. *Psittacosaurus* as currently understood is, apparently, monophyletic. *Brachiosaurus* as it used to be understood is probably not monophyletic; in addition to Mike's own phylogenetic analysis which showed a lack of evidence for monophyly, there's one that finds it to be para- or polyphyletic (I don't remember) and was presented at last year's SVP meeting. The ICZN is fine with para- and even polyphyletic genera; but few biologists these days are. Given the high probability that *Brachiosaurus* and *Giraffatitan* are not sister-groups, it was a good move to separate them nomenclaturally.

 [...] paleontologists and zoologists may have directly contradicting
 views on species identification, despite using the same nomenclatural
 system.

Different neontologists have very different views on species identification, too. There is much controversy over many individual cases and over general questions like whether subspecies should be recognized at all (as opposed to promoting them to species rank).