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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,
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
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
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.
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
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....
School of Earth & Environmental Sciences
University of Portsmouth UK, PO1 3QL
tel: 023 92846045