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Had a busy weekend with the final proofs of the WWD book. Last 
week sometime Mickey Mortimer asked...

> Can someone please explain the difference between:
> Ophidia and Serpentes
> Gymnophiona and Apoda
> Urodela and Caudata
> Anura and Salientia
> Chelonia and Testudines

As Mickey notes, various workers have recently taken to using both 
avialable names for these groups: one for the crown group, the other 
for the crown group + fossil outgroups. For reasons of brevity, I here 
use the acronym ATDOTMRCA for 'all the descendants of the most 
recent common ancestor'. Ophidia Brongniart 1800, for example, was 
defined by Lee and Caldwell (1998) for the clade that included 
ATDOTMRCA of Pachyophiidae + all other snakes while Serpentes 
Linnaeus 1758 is ATDOTMRCA of scolecophidians + 
alethinophidians (i.e. crown group Ophidia). Obviously (as Matt T is 
no doubt about to remind me) not everyone agrees with Lee and 
Caldwell that pachyophiids are basal ophidians... in which case Ophidia 
and Serpentes would be synonymous (or one of the names would be 

Similarly, Lee (1995, 1997) uses Chelonia Macartney 1802 for 
ATDOTMRCA of _Proganochelys_ + Rhaptochelydia (australochelids 
+ testudines); and Testudines Linnaeus 1758 for ATDOTMRCA of 
pleurodires and cryptodires. I believe the latter is the same group 
named Casochelydia by Gaffney. 

Anura Linnaeus 1758 is the oldest name for frogs and was applied by 
Evans and Borsuk-Bialynicka (1998) to the frog crown group. Various 
outgroups to Anura - _Triadobatrachus_, _Czaktobatrachus_, 
_Vieraella_ and _Notobatrachus_ - were then united with Anura into 
the Salientia Laurenti 1768. I guess Evans and Borsuk-Bialynicka 
(admittedly, I don't know if they were the first to do this) excluded 
_Triadobatrachus_ etc. from Anura because doubts have occasionally 
been expressed as to whether or not these taxa are frogs s.s. - thus it 
seems wise to use the less popular name (Salientia in this case) for the 
clade that includes these taxa. If you know better please tell me. Oh 
yeah, Anura has been defined as ATDOTMRCA of _Prosalirus_ + 
living frogs.

I honestly don't know if strict definitions have been applied to Urodela 
and Caudata, or to Apoda and Gymnophiona. All recent texts I've seen 
use the terms Caudata and Gymnophiona - if Urodela and Apoda have 
been erected for more inclusive clades (e.g. hypothetically Urodela 
could be _Karaurus_ + Caudata or something similar), it's news to me. 
Even _Eocaecilia_ (the most basal caecilian AFAIK) is still put within 
Gymnophiona by those authors that mention it.

School of Earth, Environmental & Physical Sciences
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