[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

SVPCA 50, REPORT I



SVPCA 50 was held on 11-13th September 2002 at the 
University of Cambridge, 2002. As the 50th meeting it may 
have been the best-attended yet, and at a very attractive, 
historic venue. 

Several main 'themes' emerged in my interpretation of the 
meeting. (1) Basal tetrapods, temnospondyls and kin and 
lissamphibians were very well represented both in talks and 
posters. (2)  _Leedsichthys_ had a conspicuous role as Dave 
Martill and Jeff Liston spoke about it for the ice-breaker 
talk on Tuesday (10th Sept) night (after Mike Taylor on 
Hugh Miller) and Jeff gave a talk on it as part of the 
conference _and_ had a poster (talk about over-exposure:)). 
(3) This time round at least it was (contra McHenry) 
'dinosaurs good, marine reptiles bad' as - excepting Mueller-
Towe, Signore and Rothery (see below) - there were NO 
marine reptile talks. Dinosaurs however occupied 4 of the 
11 talk sessions, making them the dominant group at the 
conference. (4) Unusual or outstanding artwork was the 
order of the day with Dougal Dixon's life-sized furry 
velociraptorine, an amazing life-sized Messel artiodactyl 
and a display of Luis Rey artwork. Luis' newest pieces are 
of 'Dave' (cf._Sinornithosaurus_) and 'The New Chinese 
Revolution, Part II'.  The latter depicts quilled psittacosaurs 
collecting bones and displaying confuciusornithids and 
_Cryptovolans_.

Unfortunately not all of the advertised talks or posters 
actually happened on the day, in part because some people 
were not happy about being asked to present a poster when 
they had planned to give a talk, though other factors also 
intervened as at all conferences. Frey on soft-tissue wing 
morphology in pterosaurs, Norman on 
_Heterodontosaurus_, Cruickshank on New Zealand 
plesiosaurs, Negro on hadrosaur skin and Evans on a new 
Pleinsbachian plesiosaurs were among the casualties. 

Anyway, enough of the preamble... I did not attend all the 
talks I wanted to but do here attempt to at least mention all 
of them. Oh, there is an abstract volume (Norman, D. & 
Upchurch, P. (eds) 2002, _SVPCA 50 Cambidge 2002, 
Abstract Volume_, University of Cambridge, pp. 47) but 
please don't ask me how to get one as I can't help.

BASAL TETRAPODs/NON-AMNIOTES etc

Per Ahlberg reviewed the relationships of _Ichthyostega_, 
_Acanthostega_ and other basal forms and showed how 
messy their character distribution is. _Ichthyostega_ appears 
highly autapomorphic even though it is less derived than 
_Acanthostega_. New material of _Ventastega curonica_ 
discovered in Latvia in August 2001 reveals skull features 
(e.g. internasal fontanelle) seen in some other basal forms. 
These appear to be shared primitive tetrapod features and 
the braincase and mandible of _Ventastega_ are the most 
primitive known thus far for tetrapods, being most like 
those of _Panderichthys_.

Anne Warren talked about a new basal tetrapod from the 
mid Visean Ducabrook Fm in Queensland. This material 
was previously suggested to be three taxa but all turns out to 
belong to the same big-headed, small-limbed form that 
appears to be another whatcheeriid. Maybe then this clade 
was widely distributed as representatives are now known 
from Scotland, the USA and Australia.

Jenny Clack showed how the controversial ear region of 
_Ichthyostega_ has now been largely resolved (she did not 
talk about a new basal tetrapod from Ireland as advertised). 
The 'table-tennis bat' element on either side of the 
_Ichthyostega_ braincase is a highly modified stapes.

Mike Coates discussed _Utegenia_ and covered 
seymouriamorph phylogeny as well as wider implications 
for the tetrapod tree. Missed this talk so can't say much 
more (and am not about to type out the abstract).

Lauren Tucker presented data on the late Carboniferous 
tetrapod ichofauna of south Shropshire and Andrew Milner 
showed that branchiosaurid larvae are apparently not all 
amphibamids, but that some may be dissorophid or 
trematopid larvae. 

Caecilians were looked at in Mark Wilkinson's talk on the 
scolecomorphid phallus (a protrusible, ornamented organ 
that can be species specific but is not always so) and in 
Simon Loader's poster on scolecomorphid anatomy, 
ontogeny and phylogeny.

NON-ARCHOSAUROMORPH REPTILES

Simon Harris explained how 'boil down', a statistical 
measure of character quality assessment, was used to 
examine conflicting hypotheses of turtle relationships. 
Bottom line is that Lee's characters (used to support anapsid 
ancestry) were 'weaker' than those used by Rieppel, so a 
diapsid affinity is favoured.

Marco Signore spoke about new specimens of the mesosaur 
_Stereosternum  tumidum_. These reveal a wealth of new 
details, among them the presence of a paddle encasing the 
hand, separate intercentra and pleurocentra in the vertebrae 
and a stiffened vertebral column. These and other features 
indicate that mesosaurs were paraxial swimmers and not tail 
swimmers as proposed before. No evidence for caudal 
autotomy was found. The different mesosaur taxa appear to 
have exhibited different feeding habits (_Mesosaurus_ was 
a deep-water filter-feeder and _Stereosternum_ and 
_Brazilosaurus_ were shallow-water piscivores) and adults 
and juveniles in _Stereosternum_ may also have differed in 
ecology.

Susan Evans reviewed the Lower Cretaceous lizard faunas 
of Europe and showed that many relict Jurassic lineages 
persisted here while they had disappeared elsewhere, 
perhaps because the island archipelagos of Cretaceous 
Europe ages as refugia for these small vertebrates. 
Eichstaettisaurs persisted to the Albian in Pietraroja and a 
new sphenodontian at Pietraroja has two eichstaettisaurs 
preserved as stomach contents! Multiple new taxa from 
Purbeck and elsewhere were mentioned.

Tamsin Rothery described the differences that have been 
used to differentiate tiny _Acrosaurus frischmanni_ from its 
much larger relative _Pleurosaurus_. _Pleurosaurus_ is 
about ten times bigger than _Acrosaurus_. Cocude-Michel 
was mostly responsible for arguing that the 6 acrosaur 
specimens were adults, but the absence of key ossifications 
suggest instead that they are juveniles (or even pre-
hatchlings) of _Pleurosaurus_ after all. I seem to recall that 
the possibility of the acrosaurs being a paedomorphic dwarf 
taxon was bought up in the Q&A session, but don't recall 
what the outcome was.

Laura Saila and Ian Corfe questoned the tetrapod diversity 
of St Brides Island, an Early Jurassic island located in what 
is now Glamorganshire, south Wales. The fauna here is 
depauperate compared to other fissure faunas. The Pant 4 
fissure, discovered in 1968 but never published, reveals 
several _Oligokyphus_ species, archosaur teeth, 
_Gephyrosaurus_ and three sphenodontians. A new taxon of 
_Clevosaurus_ with a short nasal process on the premax 
was reported. Other clevosaur material present may belong 
to this new species but this is difficult to determine. The 
_Oligokyphus_ in the assemblage were compared to Kuhn's 
_O. minor_ and _O. major_ and it was found that these all 
appear to be part of the same species. In fact they went 
further than this and suggested that all the _Oligokyphus_ 
material worldwide might be conspecific.

David Gower reviewed scale surface ornamentation in 
uropeltid snakes. Various scale features seen in snakes 
might related to function (dirt-shedding, anti-fouling, 
locomotion etc), but is there an over-riding phylogenetic 
control? The diversity of ornamentation in burrowing 
snakes is quite low and while the function of the scale 
features does match with phylogenies established on other 
lines of evidence, some functional aspects of the 
ornamentation remain unclear.

More to come....

-- 
Darren Naish
School of Earth & Environmental Sciences
University of Portsmouth UK, PO1 3QL

email: darren.naish@port.ac.uk
tel: 023 92846045