Re: Dino Birds (was Re: Dinosaur = extinct animal)

[chris brochu <cbrochu@fmppr.fmnh.org>]

I don't have time for extended exchanges on this today, but here are a
few thoughts in reply:


Dinogeorge@aol.com wrote:
> 
> In a message dated 7/12/99 9:00:56 AM EST, cbrochu@fmppr.fmnh.org writes:
> 
> << The overall point is that paraphyletic assemblages, above the species
>  level, are subjective, have no biological reality, and are not
>  recognized in modern systematics. >>
> 
> Paraphyletic taxa certainly have "biological reality," whatever that is. If
> monophyletic taxon A and included monophyletic taxon B are "biologically
> real," then so is the paraphyletic taxon A-B, the set of organisms that are
> in A but not in B. 

No, it isn't, because we're subjectively deciding what to subtract from
A.



Whether or not paraphyletic taxa are to be admitted into
> taxonomy is a subjective philosophical decision, just like the choice of
> which taxa should be defined as monophyletic and which might be most useful
> as paraphyletic. Despite the cladistic prejudice against them, there are
> still plenty of paraphyletic taxa recognized in modern systematics,
> including, e.g., the genus Australopithecus: all australopithecines that are
> not in the genus Homo. Among dinosaurs, the genus Hypacrosaurus is probably
> paraphyletic, since it doesn't include the species in the probable descendant
> genera Corythosaurus and Lambeosaurus (see Currie & Horner on Hypacrosaurus
> stebingeri), and the genus Chasmosaurus, since it doesn't include the species
> in the probable descendant genus Pentaceratops (see Lehman on Chasmosaurus
> mariscalensis).


I discussed my reservations about "genera" being taxa in a post not long
ago.


chris




-- 
----------------------
Christopher A. Brochu
Department of Geology
Field Museum of Natural History
Roosevelt Road at Lake Shore Drive
Chicago, IL 60605

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