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Lazarussuchus & rhynchosaurs




This is very interesting. Gao and Fox show Lazarussuchus as sister group to Choristodera. And Chris Brochu's Figure 1E shows Rhynchosauria as sister group to Choristodera.
Is it possible that Lazarussuchus is an intermediate form between rhynchosaurs and choristoderes?
And more importantly, is Lazarussuchus the most primitive of these three groups? In other words, could it possibly be the sister group of a rhynchosaur-choristodere clade?
Just speculating, Ken Kinman
********************************************************
From: darren.naish@port.ac.uk
Reply-To: darren.naish@port.ac.uk
To: dinosaur@usc.edu
Subject: THE LAST CHORISTODERES
Date: Mon, 12 Jun 2000 09:49:22 +0100

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 3Q
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