THALASSIODRACON etc.

[darren.naish@port.ac.uk]

Ekaterina wrote...

> Are they any reconstructions of these sauropterygians that were sister
> groups of the plesiosaurs. 

There are plenty of reconstructions of _Corosaurus_, _Simosaurus_ 
and other taxa which (according to Storrs and some other authors) are 
closer to plesiosaurs than to other 'nothosaurs'. Rieppel argues for a 
monophyletic Nothosauria that includes most 'nothosaurs' of Storrs as 
well as pachypleurosaurs.

> Are there any known fossils that lie outside the plesiosaur-nothosaur 
> containing clade but within the clade formed by placodonts with the 
> former two

See the papers by Storrs and Rieppel for different views. Incidentally, 
the evidence that placodonts are sauropterygians is pretty good but not 
all sauropterygian workers are convinced.

> I looked into Sander et al describing Augustasaurus where they 
> mention a primitive plesiosaur Thalasiodracon but given not in        
> formation. How much of this beast is known? 

_Thalassiodracon hawkinsi_ is a small plesiosaur from the Lower Lias 
(possibly latest Rhaetian-Hettangian) of England that was previously 
lumped into _Plesiosaurus_. It looks pretty much like _P. 
dolichodeirus_ but has a proportionally shorter neck and larger head - 
several 100% complete individuals are known: see Storrs and Taylor 
in _JVP_ (I think it was 1996). _T. hawkinsi_ individuals are always 
fairly small - less than 3 m total length. 

Have just returned from the better part of a week messing around at 
Kettleness, near Whitby (Yorkshire coast) - a veritable marine reptile 
fest with ichthyosaurs and rhomaleosaurs aplenty. Was mostly the 
filming of an ichthyosaur excavation arranged by Phil Manning and 
with many local collectors on site. Whitby Museum was fun with real 
skeletons of '_Ichthyosaurus' acutirostris_ (=_Leptonectes_), 
_crassimanus_ (= ???) and _platyodon_ (=_Temnodontosaurus_) on 
show as well as a complete _Rhomaleosaurus_ (surprisingly long 
necked) and _Teleosaurus chapmani_ (a new one on me... is it now in 
_Steneosaurus bollensis_?). I got burnt by the sun and collected lots of 
pieces of dead seabird. Found a fossil ichthyosaur centrum on the 
beach as well.

Week before that I was at York for the official opening of the Walking 
With Dinosaurs exhibition at York Museum. Great stuff. Apparently 
Prince Philip thinks that pliosaurs are still alive.

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