Darren Naish
 
 

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 plesiosaur 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 Cambridge 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 AhlbergPer 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 WarrenAnne 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 Jenny Clack 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 TuckerLauren 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.

Crocodylomorphs

Inken Mueller-Towe compared the Holzmaden crocodyliforms Platysuchus multiscrobiculatus (named by Wetsphal in 1962) with Steneosaurus bollensis and showed that they do differ in various ways. The premaxillae, nasals, coracoids and limbs of the two differ in shape and proportions but they exhibit some characters (lacrimal-postorbital contact) not seen in other teleosaurids. Platysuchus may have been a less aquatic animal than Steneosaurus

David Allen showed that Terrestrisuchus really should be regarded as just a juvenile of Saltoposuchus as all of its 'distinctive' features (lack of squamosal ridge, no rostral dentrart swelling etc) are juvenile features, plus it exhibits open neurocentral sutures in the caudals! A plot of the hindlimb proportions shows that all the Terrestrisuchus and Saltoposuchus specimens can be seen as part of a growth series. Incidentally this is all at odds with Clark and Sues (2002) who regard these two taxa as distinct and even in different sphenosuchian clades. David also tested sphenosuchian phylogeny and found the group to be paraphyletic. From what I could write down, Sphenosuchus and Dibothrosuchus grouped with Crocodyliformes while Saltoposuchus did not.

Pterosaurs

Sarah Sangster re-examined hindlimb morphology in Dimorphodon. She concluded that the plantigrade pes, anterior CoG and other features made a bipedal posture impossible.

Dave UnwinDavid Unwin provided a thorough analysis of pterosaur hindlimb morphometrics and locomotor modules. A la Gatesy and Middleton, pterosaurs (from all groups) were plotted onto ternary diagrams and found to occupy a rather small morphospace which overlapped that of both bats and birds (interestingly, the bird and bat clouds did not overlap). Bats occupy about 50% of the morphospace that birds do, and pterosaurs occupied a small space than bats. Forms for which the wing membrane is known were scattered throughout the cloud demonstrating that extensive patagia are not an unusual feature of one pterosaur subgroup.

Michael FastnachtMichael Fastnacht reported an amazing 3-D, articulated pterosaur specimen from the Langenberg locality at Oker, near Hanover. It includes a complete pelvis, femora and vertebral column and differs from all described taxa. The femora are most like those of Dsungaripterus weii and the very thick-walled tibia also resembles those of that taxon. It thus appears to be a true dsungaripterid and thus maybe the first from Europe (though some scrappy Romanian material might represent this group). The thick tibial walls are obviously unusual for an otherwise thin-boned group - could it be a strengthening adaptation for forms that have to resist impact when landing on the ground?

Dinosaur Tracks

Two talks focused on trackways. Jesper Milan looked at undertrack preservation using live emus as trackmakers. Anatomical details disappeared in transmitted tracks while the track shape remained recognisable. Whether undertracks ever form has recently been contested by Nadon.

Peter Griffiths talked about a fantastic trackway from Crayssac where a small theropod (approx. hip height 47 cm), running at approx. 4 m/s, suddenly executed a dynamic turn and then clearly ran back 180 degrees to its original line of travel. Why it performed this abrupt about-turn is unknown BUT it does so at the exact same point as another dinosaur trackway is observed (thus implying avoidance behaviour). At the turning point, the tracks show that the animal rotated rapidly on one foot. As it did its tail swiped along the ground, cutting into the sediment and leaving a prominent trace. The turn was clearly abrupt, dynamic and executed 'on a sixpence' thus, contra Carrier et al's recent paper about inertia preventing long-tailed theropods from being rapid turners, the trackway indicates that long-tailed dinosaurs could turn abruptly, and used their tails dynamically as they did so.

General Dinosaur stuff

Michael Parrish discussed rib angulation and scapulocoracoid position in dinosaurs. Ribs should be swept backwards, obviously. Looking at sauropod ribs, Parrish noted concave areas on the dorsal surfaces of sauropod thoracic ribs that appear to correlate with scap-coracoid position. Adjusting the pectoral girdle accordingly, he found that the scap-coracoid was located a bit more ventrally than normally recontructed, and consequently that the sternal plates became somewhat 'flattened out' and lay closer to the ventral surface of the thorax than normally thought. The implications this has for dinosaurian musculature were discussed.

Angela Milner showed that proteinaceous material (specifically proteoglycans) could be detected in Iguanodon bones from Smokejack's Pit, Surrey. This is the first report of proteoglycans from fossil bone.

Darren Naish discussed newly recognised material of Eotyrannus and its possible implications, a large brachiosaurid cervical vertebra that shares some features with Sauroposeidon, and the palaeopathologies seen in the holotype of Neovenator and the Iguanodon found with it. Both animals were bristling with injuries and the Neovenator preserves evidence of osteoarthritis: the first report of this in Dinosauria excepting Iguanodon bernissartensis and chickens. Judging from the feedback I got, this was technically the weakest and stylistically the crappest SVPCA talk of them all. Still, you gotta laugh.

Colette Cherry spoke about bone histology in Thecodontosaurus and Anusuya Chinsamy reviewed bone depositional rates among Dinosauria. Depositional rates are significantly affected by environmental conditions and, following experiments on quails, I think Chinsamy's point was that the short developmental time of extant birds means that the potential for variation in bone developmentis reduced relative to the variation in other dinosaurs (and this may be why extant birds tend not to develop LAGs). She did state that LAG development was not simply a plesiomorphic thing (contra Padian et al.) seeing as herrerasaurs apparently lack LAGs.

Sauropodomorphs

Adam Yates reviewed the prosauropods of the Lowenstein Formation (better known as the Stubensandstein) of Germany. Employing a specimen-based analysis of 34 (I think) characters, Sellosaurus gracilis was found to share derived characters with Plateosaurus and thus was sunk into the latter genus. Meanwhile, Efraasia was resurrected from Sellosaurus and lacks the derived characters of Plateosaurus (and in fact of the Plateosauria). It was shown that Teratosaurus minor has the same diagnostic characters as E. diagnosticus, so minor is the oldest available name for the species. In Adam's phylogeny, Efraasia is a stem-sauropodomorph (as is Thecodontosaurus and Satunalia I think [couldn't copy down the whole cladogram fast enough]) while Riojasaurus + Plateosauria form a monophyletic Prosauropoda that is sister to Sauropoda.

Kent StevensKent Stevens talked about a specimen close to my proverbial heart, an articulated, complete sauropod forelimb from the Isle of Wight discovered by local collector Keith Simmonds. Discovered adjacent to other vertically-mired sauropod limbs (see my previous comments on these specimens Keith Simmons in the writeup for the Portsmouth SVPCA meeting), this specimen definitely lacks a pollex claw and carpals, has an ulnar olecranon and has tightly bundled metacarpals in which mets I and V (nearly touching at the back of the hand) may have worked as a functional heel. The big surprise is the identity Kent proposed for this form (it wasn't a surprise to me as I'd had it discussed to me at length prior to the talk, but anyway...): based mostly on the proportions, he argued that it was a diplodocid, and more specifically was closest to Apatosaurus. The glenoid was 1.8 m off the ground suggesting a total length of 9.8 m, so if this is an apatosaur it's a dwarfed, thumbless form with more columnar limbs than Jurassic diplodocids. However... Paul Upchurch was not happy with this and, as you may gather from the lack of a pollex ungual and ulnar olecranon (and other characters), argued that a diplodocid ID was unlikely and that the specimen seems instead to be a basal titanosaur.

Eric Buffetaut Eric Buffetaut showed how new skull material of Phuwiangosaurus definitively links it with the nemegtosaurids (e.g. P. sirindhornae has the same caudal quadrate fossa as does Quaesitosaurus, slit-like supratemporal fossae etc) and is in agreement with a titanosaur affinity for nemegtosaurids. Eric also showed that Huabeisaurus agrees with Phuwiangosaurus in many features and is probably a close relative. Tangvayosaurus is also similar.

I initially thought Eric was talking about Hudeisaurus (which resulted in a very confused conversation with Sasidhorn Khansubha).

Jeff Wilson discussed trends of neck elongation among sauropods. Early sauropod evolution is characterised by duplication and incorporation events (i.e., eusauropods incorporated a dorsal into a cervical and exhibit a duplication of two cervicals relative to the ancestral condition) but, excepting diplodocids (which incorporate two more dorsals into cervicals), later sauropod clades are not characterised by any neck-lengthening events. Instead, individual genera seem specialised for their own neck lengths.

More general Dinosaur stuff

Paul UpchurchPaul Upchurch discussed the methods behind his recent analysis of dinosaur biogeography.Using Components Analysis, significant area relationships correspond closely with those predicted from Mesozoic palaeogeography. At least some of the evidence therefore supports the idea that dinosaur distribution was mostly vicariance-driven. For the full story see the Upchurch et al. Proceedings paper.

THEROPODS

Paul BarrettPaul Barrett showed that Norell et al's recent claim of filter-feeding and the presence of laminae in ornithomimids was, err, somewhat questionable (which makes you wonder how this paper got into Nature). In fact the pillar-like vertical structures seen on the median surface of the ornithomimid rostrum are pretty much identical to the same structures seen in sea turtles and ornithischians and are more to do with the presence of rhamphothecae than anything else (Nick Longrich and I were already onto this.. Paul has beaten us to it). Paul also investigated the energetics of filter-feeding and showed that it would not have been ecologically possible for ornithomimids to survive this way, even given a variety of postulated metabolic regimes. More likely (rediscovery of GSP 1988), ornithomimids were herbivores.

Aha, how relevant... Marco Signore argued that mantids and theropods may have exhibited similar snap-capture forelimb devices and that this may explain the avian flight stroke. Marco proposed that the bowed ulna evolved to resist impact. Apparently some martial arts use forelimb strikes similar to those postulated for maniraptorans and this seems to be part of Marco's inspiration. As I pointed out in the Q&A session, the problem with comparing mantids and theropods is that mantids grab prey by impaling them on spikes between the distal-most limb segment and the 'lower arm'. Conversely, the theropod strike has a prominent medial component and prey could not have been held between the hand and lower arm. In that case are the two systems really that analogous?

Gareth Dyke talked about the new Maastrichtian ornithurine just published in Naturwissenschaften and not all that different from Ichthyornis, though bigger. The larger picture of bird evolution around and across the KT boundary was discussed and Gareth stated that 'at face value' the data supports Feduccia's bottleneck hypothesis. I don't see how this can be so though seeing as there is at least some evidence of neornithine lineages originating in the Late Cretaceous. Furthermore, I've just looked at the abstract and Gareth says otherwise there, stating 'Range correlations of lineages of Cretaceous birds, combined with gap analysis and the estimation of clade confidence intervals shows that there is little evidence for a 'bottleneck' in diversity at the K-T boundary'. Tsk tsk.

David Waterhouse gave details on a new well-preserved, quite complete Green River Formation charadriiform. In his phylogenetic analysis, David did recover a monophyletic Charadriiformes but is appears pretty different from published versions with a radically polyphyletic Scolopacidae scattered all about the tree. The new taxon grouped closest to plovers, coursers and kin.

Ornithischians

There was only one ornithischian talk in the whole meeting.. Jo Parish's on ankylosaur evolution and palaeobiology. Shamosaurine characters were regarded as weak and Cedarpelta and Shamosaurus did not group together: Cedarpelta and Minmi were basal ankylosaurs outside of Ankylosauridae + (Polacanthidae + Nodosauridae). Polacanthids show convergences with ankylosaurids, especially in cranial characters. The development of the acromion process appears to correlate with the presence of pectoral spines and the form of dp crest. Percy Butler

Synapsids

Matt Allison covered gorgonopsian taxonomy and phylogeny (but I was in the pub and missed it) and Percy Butler argued that MTBs must be derived from harimiyids and that both groups are more primitive than most other mammals (hmm, same talk as SVPCA Portsmouth). Assorted presentations on mysticete feeding, ungulates, carnivorans and primates followed, making mammals better represented at this SVPCA than most others.

Posters

Dino FreyAs mentioned earlier in these reports, marine reptiles simply didn't get represented in the talks at all. Consequently there were more poster presentations on these animals than normal. Dino Frey and Marie-Celine Buchy showed how a new Mexican pliosaur simply could not have the same flow-through internal narial system as proposed by Cruickshank, Small and Taylor;Marcela Gomez presented details on a new Kronosaurus species (most similar to K. boyacensis) from Colombia; Richard Forrest revealed that plesiosaurs exhibit 'M-type' and 'E-type' neck stiffening (M-type forms raise the zygapophyses higher onto the neural arch, E-types lock the neural spines together but lower the zygapophyses) and that these two types may be fundamentally different (genetically and phylogenetically); and Adrian Doyle and Sandra Chapman showed that the type specimen of Stenopterygius acutirostris has been relocated in the NHM collections.

Marcella GomezAs for stuff other than marine reptiles... Lorna Steel provided details on a new partial Anhanguera-like ornithocheroid pterosaur skull from the Isle of Wight; Steve Sweetman illustrated a plethora of new Isle of Wight Wessex Fm microvertebrates (including albanerpetontids, frogs, lizards, tiny ornithischians etc) and Barry Clarke presenting a very interesting re-interpretation of anuran origins (saltation has been over-emphasised and walking must have been more important in evolution of the basal frog body plan).

Cambridge 2002

Darren Naish on...


Basal Tetrapods/non-Amniotes etc
Non-Archosauromorph Reptiles
Crocodylomorphs
Pterosaurs
Dinosaur Tracks
General Dinosaur stuff
Sauropodomorphs
More general Dinosaur stuff
Ornithischians
Synapsids
Posters'