The 51st SVPCA

[darren.naish@port.ac.uk]

Ok, I've been promising for a while now that I'd do a 'brief' 
report on what happened at SVPCA. Just about have time 
for this today, so here we go...

The 51st Symposium of Vertebrate Palaeontology and 
Comparative Anatomy was held between Wednesday 17th 
and Friday 19th September 2003 at the Oxford University 
Museum of Natural History. This is a fantastic venue as you 
are literally surrounded by skeletons, replicas and taxiderm 
specimens of numerous animals, both modern and fossil. 
This year the coverage of different vertebrate groups 
seemed fairly even, with basal tetrapods, lepidosaurs and 
other assorted diapsids, marine reptiles, pterosaurs, 
dinosaurs and mammals all being reasonably well 
represented. I didn't attend all of the fishy talks so won't be 
reporting on those, nor will I have time to report _all_ the 
talks, let alone the posters. But the following covers the 
bulk of the tetrapod presentations given at the meeting...

BASAL TETRAPODS

Per Ahlberg (et al.) revealed the increasing strangeness of 
_Ichthyostega_. The animal is now becoming so odd that 
basal tetrapod evolution is becoming too complex - we 
should ignore all of this new work and just pretend that 
Jarvik got it all right:) Jarvik illustrated a very odd neural 
spine morphology for _Ichthyostega_, but the same 
morphology is clearly not depicted in his skeletal 
reconstruction. In fact _Ichthyostega_ has extremely 
differentiated neural spines and a reasonably well 
'segmented' axial skeleton with a distinct neck, a longish 
lumbar region, and also a tail far shorter proportionally than 
that depicted by Jarvik. Superficially in fact the axial 
skeleton recalls that of a mammal, so _Ichthyostega_ is now 
looking more suited for terrestriality than other basal 
tetrapods. Its scap-coracoid is proportionally bigger than 
conventionally shown. _Elginerpeton_ is quite similar to 
_Ichthyostega_ and the two might belong to a monophyletic 
ichthyostegid clade.

Hennig Blom (et al.) discussed the forelimb skeleton of 
_Ichthyostega_ and also showed that reality was quite a bit 
different from things depicted by Jarvik. As the lower arm 
of _Ichthyostega_ is extended, the wrist broadens and 
twists, the result being a peculiar specialised ?paddling 
action not particularly suited for either walking or 
swimming. Pronounced ontogenetic changes seem to have 
occurred in _Ichthyostega_ forelimbs.

Jenny Clack discussed _Silvanerpeton miripedes_, a taxon 
originally described (by Clack) as an anthracosaur. New 
preparation and analysis shows that _Silvanerpeton_ has the 
spike-like tabular horn seen in embolomeres and, together 
with _Eldeceeon rolfei_ (which was also reanalysed), it 
seems to be close in the tree to basal anthracosaurs, 
microsaurs and stem amniotes. _Casineria_ (published 
recently as the oldest tetrapod with a pentadactyl manus) 
grouped close to microsaurs and its removal from the tree 
affected the positions of _Silvanerpeton_ and _Eldeceeon_.

Marcello Ruta discussed the seymouriamorph 
_Ariekanerpeton_ and showed how it is sister to 
_Discosauriscus_, the two forming a Eurasiatic 
seymouriamorph clade of which _Utegenia_ is the sister 
taxon. _Seymouria_ is a sister to the _Utegenia_ + 
Eurasiatic clade and thus it doesn't seem that 
_Ariekanerpeton_ and _Seymouria_ are close kin. 
Seymouriamorph monophyly is not all that secure and 
virtually all of the characters used to unite the group are 
seen in other groups.

Carol Hopkins discussed later Permian tracks that move 
diagonally up dune surfaces, yet have toe marks directed 
straight upslope. By forcing assorted living lizards to climb 
up little sand dunes she demonstrated how animals might 
produce these kinds of tracks.

LISSAMPHIBIANS

Sue Evans (et al.) described new Jurassic salamander 
specimens from the Morrison Fm and reviewed the fossil 
record of Mesozoic salamanders. _Laccotriton_ and 
_Sinerpeton_, recently described as possible stem 
cryptobranchoids, are Early Cretaceous and not Jurassic as 
claimed, and the same is probably true for the Jiulongshan 
Fm's _Chunnerpeton_ (recently claimed to a 
cryptobranchid). A new Morrison Fm taxon has been 
scanned at the Univ. Austin, Texas, and reveals loads of 
good character information - some of the characters are 
contradictory to present understanding but the specimen 
exhibits some salamandriod characters and be sister to this 
group.

PARAREPTILES etc

Paul Barrett spoke about new material of the 
procolophonoid _Barasaurus_ and of younginiform 
tangasaurid material from Madagascar which show that 
these two taxa survived the PT event. Procolophonoid taxa 
have a particularly high rate of survival across the 
boundary.

MARINE REPTILES

Mark Evans discussed the new Pliensbachian plesiosaur 
discovered in Gloucestershire in 2000 (mentioned 
previously in my writeup of the SVPCA Portsmouth 
meeting). It comes from the 'Pliensbachian Gap', a time at 
which no named plesiosaur taxa are known, and represents a 
3m long adult plesiosaur that combines assorted pliosauroid, 
elasmosaurid and other features. The neck was shortish, the 
caudal extensions of the premaxillae are short, and one of 
the strangest things is that the neural spines are D-shaped in 
cross section.. AND, they alternative such that the curve of 
the D faces left on one spine, right on the next, left on the 
next and so on. Very odd. When included in O'Keefe's data 
set the specimen was a basal polycotylid (giving the group a 
ghost lineage of c. 90 million yrs), but in other data sets it 
was variously sister to rhomaleosaurs, or a basal plesiosaur.

Richard Forrest analysed the many (c. 150) isolated 
plesiosaur vertebrae from the Rhaetian Bone Beds. 
Cervicals are better represented than other verts by a factor 
of three. Using assorted statistical techniques (including 
PAST and PCA) applied to something like 27 different 
vertebral measurements (Richard said he sometimes takes a 
break from this measuring and goes and does something 
more interesting, like watching paint dry), Richard showed 
how the vertebrae of plesiosaur taxa generally cluster neatly 
together, so these measurements DO provide good 
information. Two distinct kinds of plesiosaurs are clearly 
present in the Rhaetian BB (this is significant because these 
are the earliest records of plesiosaurs), one of which is 
allied to rhomaleosaurs.

CROCODYLIFORMS

Daniela Schwarz discussed the locomotor abilities of 
dyrosaurid crocodyliforms. Dyrosaur vertebrae look odd 
(compared to extant crocodylians) as they have tall neural 
spines throughout the column with the tallest spines being 
in the neck and cranial region of the tail. The resulting 
muscle attachments would have made a self-carrying I-beam 
construction (like that seen in extant crocodylians) 
impossible because the insertion angle of the epaxial 
musculature on the osteoderms would have been too high to 
maintain the I-beam-type construction. An inverse T-beam 
carrier was hypothesised and because dyrosaurs then lacked 
effective bracing against transverse shear loads they 
probably couldn't high-walk (or, at least, large individuals 
couldn't high-walk). Various aspects of their axial and 
appendicular morphology indicate that dyrosaurs were 
improved swimmers compared to extant crocodylians.

PTEROSAURS

David Unwin discussed pteraichnites.. that's pterosaur 
tracks to the rest of us... and reviewed their occurrences, 
which clades appear to be represented (_Purbeckopus_ 
might be an azhdarchoid and _Haenamichnus_ might be an 
azhdarchid), and what they reveal about pterosaur 
behaviour. Many tracks show possible traces of feeding 
behaviour. The best line in Dave's talk: "How sure are we 
that these tracks were produced by pterosaurs? Well we're 
_bloody_ sure thankyou very much". However the best bit 
of Dave's talk :) was at the question session at the end: Paul 
Maderson (a Rubenite/Feducciary) stood up and said how 
_appalled_ he was that Dave and his colleagues are still 
proclaiming that pterosaurs had body hair, whereas in fact 
they clearly had reticulate scales like those of rattlesnakes. 
Indeed (Maderson argued), Lingham-Solaire has just shown 
that hair-like fibres can be the result of decomposition of 
collagenous skin layers. 

Lorna Steel (accompanied by David Unwin) discussed a 
new toothed ornithocheroid from the Wessex Fm of the Isle 
of Wight. The specimen exhibits _Anhanguera_-like keels 
near its jaw tips as well as a pteranodontid-like parietal crest 
but it isn't the first pterosaur reported to combine teeth these 
features as another new ornithocheiroid (published in the 
new Mazin & Buffetaut pterosaur volume) also combines a 
pteranodontid-like crest with a more typical ornithocheirid 
toothy jaw morphology.

Eric Buffetaut spoke about a natural cast of a large 
pterosaur humerus discovered - unlabelled - in the old 
collections of the Natural History Museum at Troyes, 
France. The specimen appears to come from the Lower 
Cretaceous 'Toxaster Limestone'. At 350 mm it is big (the 
biggest _Pteranodon_ humerus reported by Bennett is 316 
mm long) and appears to come from an azhdarchid.

ORNITHISCHIANS

David Norman discussed new work on 
_Heterodontosaurus_, its anatomy, and preliminary work on 
its affinities. In reviewing other ornithischian groups, he 
noted that Lucas' identification of  _Tatisaurus_ as a 
scelidosaur was completely wrong, and new skull 
interpretations of _Scelidosaurus_ and _Lesothosaurus_ 
were shown. Norman showed various cladograms produced 
by his data, the best supported of which seemed to be (I 
might be wrong) that _H. tucki_ was sister to 
Marginocephalia. However, it didn't take much to find a 
similarly supported tree in which _H. tucki_ was sister to 
thyreophorans, and other combinations were possible. 
Interesting indeed was Norman's conclusion that new 
ornithischian taxa presently in the works will disturb the 
present, 'stable' phylogeny of the Ornithischia.

Bernd Herkner discussed the remounting of the Frankfurt 
_Triceratops_ specimen. They simply couldn't get the 
forelimbs to match preserved trackways and had problems 
in getting the limbs into an anatomically reasonable pose. 
Don Henderson pointed out after the talk that apparently the 
trackways Bernd et al. were looking at are problematic: 
apparently they aren't a complete trackway but rather one 
forefoot and one hindfoot print, or something like that. 
However, also problematic was the fact that the Frankfurt 
_Triceratops_ has its ribs (and therefore its 
scapulocoracoid) mounted incorrectly, so no wonder they 
can't get the limbs into an anatomically correct position. I 
pointed this out to Bernd: they are aware of this but cannot 
dismantle and remount the whole skeleton. So the problem 
isn't with the forelimbs, but with the whole skeleton. 
Incidentally the specimen itself is a composite of four 
partial skeletons.

SAUROPODOMORPHS

Paul Upchurch covered the confused taxonomy and 
systematics of _Cetiosaurus_, much of which has just been 
sorted out by Paul and John Martin in their recent papers. 
They still need to petition the ICZN to propose that _C. 
oxoniensis_ be designated the type of _Cetiosaurus_ (rather 
than _C. brevis_). Paul showed the new phylogeny in press 
(?) for _Dinosauria II_ and _Cetiosaurus_ is part of a clade 
including _Barapasaurus_ and _Patagosaurus_.. so, 
monophyletic Cetiosauridae after all.

Donald Henderson used computer-generated sauropod 
models to test for centres of mass, and to see how well these 
matched with narrow- and wide-gauge trackways (wgts). He 
found that brachiosaurs were stable when producing wgts 
and that diplodocids weren't, and similarly brachiosaurs 
were unstable when forced to produced ngts. The 
conclusion was that the evolution of wide-gauge gaits 
resulted from huge size but this is questionable given that 
some diplodocoids may have exceeded the biggest 
brachiosaurs (and titanosaurs) in size, as Paul Barrett 
pointed out after the talk.

THEROPODS

Eric Buffetaut discussed some tiny theropod eggs 
discovered over a couple of years at one of his team's Lower 
Cretaceous Thailand sites. The eggs (each of which is 
something like 30 mm long or less) certainly exhibit 
theropod-style eggshell texture, probably all belong to the 
same next, and contain bones. Very very small bones. A tib-
fib seen in cross section was shown: surprisingly, even 
though the whole tibia must have been only a few mm long, 
a prominent cnemial crest and medial excavation on the 
fibula were both evident. Whatever theropod produced the 
eggs, it must have been very small. Possible contendors 
include microraptors and epidendrosaurs.

Steve Hutt discussed a few new large elements from Isle of 
Wight theropods, mostly manual phalanges. The elements 
are huge and when compared to the phalangeal lengths and 
proportions of large theropods with complete hands they 
suggest that there were some really really big theropods on 
the Isle of Wight in the Lower Cretaceous. Steve ended the 
talk by producing the hand he has made (based on 
_Allosaurus_) in which the largest of the IoW phalanges 
was _assumed_ (parsimoniously) to represent the biggest 
phalanx in the hand. The resulting hand is obscenely large, 
more than 50 cm long. Naish & Hutt in prep.

Darren Naish discussed a new small theropod from the 
Santana Formation of Brazil, it includes a good pelvis and a 
near-complete tridactyl manus and has features showing that 
it isn't referable to SMNK 2349 Pal (the compsognathid 
which now has a new generic name), nor to 
_Santanaraptor_. Because the specimen combines a 
compsognathid-like pelvis with a rather 'basal-looking' 
hand, it might be evidence for compsognathid paraphyly (as 
argued by Longrich), but when included in assorted 
analyses this didn't turn out to be the case - compsognathid 
monophyly was upheld and the new specimen appeared 
further down the tree. The highlight was definitely at the 
end where I donned Martill's famous hat:)

Paul Maderson spoke about feather development, how 
ridiculously complex it is, and how no-one has even 
published a proper description of the whole process. He is 
not happy with the Prum & Brush model and was just 
starting to talk about _Longisquama_ at the end when he 
ran out of time. Needless to say, Maderson is still insisting 
that _Longisquama_ still represents the best candidate for a 
creature with 'proto-feathers'. 

Emily Rayfield showed some fantastic animations of bite 
motions and the inferred kineticism of the _Allosaurus_ 
skull. Different kinds of cranial deformation occurred 
according to bite position and bite force magnitude.

Angela Milner and Patricio Dominguez-Alonso (et al.) 
discussed high-resolution CT scans of the London 
_Archaeopteryx_ braincase. Very very impressive and 
answered a lot of questions. The foramen magnum was 
bigger than thought previously and, while large olfactory 
lobes were present, _Archaeopteryx_ appeared to have a 
bird-like brain with laterally displaced optic lobes, a 
telencephalon contacting the cerebellum, and semi-circular 
canal measurements overlapping with those of extant birds.

Estelle Bourdon spoke about a new genus of prophaethontid 
from the Palaeocene of Morocco. The taxon includes a good 
skull (which is good given that prophaethontids are known 
from so few specimens, yet already have a good skull in 
_Prophaethon shrubsolei_ from the English London Clay) 
and, while it shares many characters with _P. shrubsolei_, 
the new taxon also differs in some aspects. Prophaethontids 
share with phaethontids a dorsal tympanic recess of a 
particular shape and position and thus might both form a 
clade.

Ella Hoch revealed a distal humerus from the Miocene of 
Denmark - it belongs to a puffin of the type now restricted 
to the Pacific.

Jolyon Parish gave a talk on dodo phylogeny. By combining 
Janoo's morphological and Shapiro et al's molecular data 
sets, Jo showed that dodos and solitaires (and also 
_Natunaornis_, which came out as sister to _Raphus_ + 
_Pezophaps_) are nested within Gourinae, and that 
Gourinae itself is a basal columbid clade (more basal than 
the position proposed by Shapiro et al.). The finding of 
_Natunaornis_ (from Fiji) as sister to _Raphus_ + 
_Pezophaps_ is in keeping with other lines of evidence 
which suggest that these Mascarene birds descend from SE 
Asian ancestors that migrated NW across the Indian Ocean.

SYNAPSIDS

Won't be discussing the synapsid talks too (have way run 
out of time) but the following things came up which will be 
of interest.. Marcelo Sanchez-Villagra (et al.) presented 
their new data on _Phoberomys pattersoni_, the giant 
caviomorph from Upper Miocene Venezuela. Not only is it 
found in an assemblage that includes _Stupendemys_ the 
giant terrapin, the fauna also includes several taxa of large 
crocodylians, the biggest of which are something like 10 m 
long! 

Robert Asher (et al.) showed how _Necrolestes_ is most 
likely a metatherian.. what will be interest to some here 
however is that Asher clearly stated at the beginning of his 
talk that most data now indicates that 
insectivores/lipotyphlans are not monophyletic and he 
therefore seemed positive to the idea that tenrecoids are part 
of Tenrecoidea. This is significant because in some of 
Asher's previous papers he has noted that morphological 
evidence generally does not favour the placement of 
tenrecoids within Afrotheria.

Mesozoic mammals and near-mammals were well 
represented, with talks by Jose Bonaparte, Tom Kemp, 
William Clemens and Fuzz Crompton.

Well, I enjoyed myself and am looking forward to next year 
(to be held at Leicester). But the next conference on the 
aggenda is the British Dinosaurs Seminar, held on the Isle 
of Wight this November. Am preparing for that right now, 
so better get back to work....

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

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