PROBLEM WITH AMPHIBIAN GILLS

[darren.naish@port.ac.uk]

Something has been troubling me of late, and I hope you'll forgive me 
for bringing this up in a forum more inclined toward dinosaurs than 
other tetrapods.. nevertheless the issue is relevant to Mesozoic 
life.

It is artistic convention to reconstruct certain Palaeozoic - early 
Mesozoic amphibians with bushy or branched external gills, like those 
seen in extant neotenous caudates and most lisamphibian larvae. Is 
this idea based on nothing more than the idea that, because extant 
aquatic lisamphibians sometimes have external bushy gills, ancient 
fossil ones did too? Or is there some proper evidence? I am aware 
that branchiosaurs and various other fossil larval amphibians really 
do have bushy external gills (they can often be seen in 
well-preserved individuals), but what about all these pictures of 
bushy-gilled plagiosaurs, _Ophiderpeton_ and so on? 

If there is no good evidence for bushy external gills in these fossil 
taxa, I am wondering if they should be removed. Extant 
_Megalobatrachus_, which is virtually entirely aquatic and can reach 
1.5 m and more, has no external gills thus big aquatic lisamphibians 
do not need them. 

I'd be interested in any comments on this, especially if you are an 
amphibian expert and know the answer. Where is Adam Yates when you 
need him... 

"We're doomed"

DARREN NAISH
darren.naish@port.ac.uk