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Re: Dinosaur a tecnical term; fish is not (was RE: Fish with milk (Sheesh spinoff))




On 27/10/2006, at 1:31 PM, evelyn sobielski wrote:


essentialism. Types were
held to be the exemplars of some taxon (for
instance, there was
commonly a "type species" for genera in the early
19thC), but they
did not have to bear all the characters of the
taxon's other members.

Every Linnean genus still requires a type species - the one which is first described as member of that genus or in cases like splits a newly designated one*. Hence "name-bearing type". If you consider a genus a clade (which it should ideally be), the type species is the subclade where whe containing clade of which bears that name if not a junior synonym. Thus, if the type species gets removed from a genus, it takes the genus name along with it. At least that's how it works in zoology, but I think everywhere else too.

But as I understand it, not being a taxonomist myself, we no longer require that the type species is the most "typical" of the genus. That is to say, that the type species has the most general characters that are the differentiae of the genus.


--
John S. Wilkins, Postdoctoral Research Fellow, Biohumanities Project
University of Queensland - Blog: evolvethought.blogspot.com
"Darwin's theory has no more to do with philosophy than any other
hypothesis in natural science." Tractatus 4.1122