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Re: PROBLEM WITH AMPHIBIAN GILLS






On Tue, 19 May 1998, Tony Canning wrote:

> Can anyone clarify, IS there a monophyletic label that describes early
> "amphibians" + lissamphibia (e.g. anamniota?), excluding amniota, and if
> so, what is the definition and what groups are included?
> 
> Thanks in advance for help on this one

Well there are two possible labels to describe the monophyletic group in
question (that is the sister group of the Amniota + its stem). The one I
like is simply "Amphibia". This would be a stem based definition, I would
then use "Lissamphibia" as a node based name for the extant crown. However
the names that may have priority under Phylogenetic Taxonomy would be
"Temnospondyli" for the stem based total group and "Amphibia" for the node
based crown group. This was the scheme used by De Quieroz and Gauthier in
their classic paper on PT. I don't like it because it is based on the
assumption that modern amphibians are derived from within the
Dissorophoidea (includes things like Cacops and Platyhistrix) which MAY
not be the case. 
Anamniote is ageneral descriptive term for any terrestrial limbed
vertebrate that does not have amniotic eggs. It is a paraphyletic
assemblage and includes stem lissamphibians, stem amniotes and stem
tetrapods.

Adam Yates