THE LAST CHORISTODERES

[darren.naish@port.ac.uk]

On choristoderes, Tim wrote..

> The youngest record for the Choristodera is Oligocene (the 
> appropriately-named _Lazarussuchus_).  

_Lazarussuchus_ was recently excluded from the Choristodera by Gao 
and Fox - they made it it the sister-taxon of this clade. Therefore 
Eocene champsosaurs are the youngest members of the group. 
_Lazarussuchus_ (living up to its name with a ghost lineage that 
extends from perhaps the Late Triassic to the Oligocene) was aberrant 
compared to true choristoderes, being relatively short skulled and 
apparently semi-terrestrial. 

Why choristoderes are so elusive in the fossil record is just wierd.  
Maybe they were always rare and (???) sometimes inhabited 
environments where preservation was infrequent. I've never handled 
any choristodere material, but I wonder if isolated choristodere 
elements possess too few diagnostic features to be identified. 
Choristoderan elusivity has been much discussed in the literature (e.g., 
Storrs and Gower, Evans and Hecht). Is elusivity a word? 


DARREN NAISH 
PALAEOBIOLOGY RESEARCH GROUP
School of Earth, Environmental & Physical Sciences
UNIVERSITY OF PORTSMOUTH
Burnaby Building
Burnaby Road                           email: darren.naish@port.ac.uk
Portsmouth UK                          tel: 01703 446718
P01 3QL