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SVPCA, part 3



My third and final attempt at summarising the events of SVPCA (not SVPCVA as I wrote in the header for part 2). To those of you who have requested the abstract volume, I can now send the whole volume as an email attachment. Email me offline if you?d like one sent. Though SVPCA meetings have traditionally not ever been written up, meaning that the contents have remained mysterious to those unable to attend, it looks likely that the Dinosaur Society will do a write-up, and that this will appear in the next issue of the Quarterly Review. I say this as I have just gotten hold of vol. 3 no. 5 of The Dinosaur Society?s _Quarterly Review_ (from earlier this year) and it has a two page report on the 47th SVPCA (Edinburgh, Sept. 1999). I don?t know what the status of the American Dinosaur Society is ? has it died? ? but the UK version, under the supervision of Jeff Liston, Arthur Cruickshank, John Martin and Dougal Dixon, has returned with a renewed vigour and is definitely worth getting involved with.

Returning to the 48th SVPCA, I have remembered various other archosaur and marine reptile presentations that I forgot to mention last time. This is mostly because some were posters, not talks. They are still worth mentioning however.

THEROPODS

Gerardo Mazzetta: Some functional aspects of the skull of the South American horned theropod _Carnotaurus sastrei_ (Saurischia: Theropoda).

As per Bonaparte et al., Mazzetta argued that _Carnotaurus_ had a highly kinetic skull and could gape widely to swallow large objects. A prokinetic hinge rostral to the orbits would have allowed (as in birds) elevation of the rostrum while the eyes could remain fixed on prey. RFTRA was used to compare _Carnotaurus_ with _Ceratosaurus_: the former had vaulted its skull for a fast, rather than strong, bite. _Carnotaurus_ was envisioned as an active predator of fast, small prey. I never got to meet Mazzetta and wanted to ask how confident he was that the type skull of _Carnotaurus_ is not distorted: Goodwin et al., in their initial presentation on _Majungatholus_, suggested that the deep and narrow skull shape of _Carnotaurus_ owed itself to compaction and might not have been natural. Also, I?m a bit sceptical of cranial kineticism in this animal (though I only have the monograph to go on and haven?t examined the specimen).

PTEROSAURS

Sarah Sangster: A new monograph of _Dimorphodon_.

Sarah is working on remonographing _Dimorphodon_ ? both Owen?s and Padian?s works have some conspicuous misinterpretations and reconstructions that differ from what is really seen in the material. A new skull reconstruction was shown.

MARINE REPTILES

M. S. Arkhangelsky: Ichthyosaurs of the Volga region (Russia).

Sadly Arkhangelsky did not attend, so no talk or poster. But it?s worth recounting some of the stuff it says in his abstract because there are quite a few new names. _Ophthalmosaurus calloviensis_, named by Arkhangelsky in 1999, is a new species from the Callovian of Saratov based on a paddle. The new family name Undorosauridae Efimov, 1999 is used for a group that includes undorosaurines (including _Undorosaurus_ Efimov 1999 and _Plutoniosaurus_ Efimov 1997) and platypterygiines. However (this is my comment, not Arkhangelsky?s), Platyptergiinae was erected by Bardet in 1994 so Undorosauridae should really be called Platypterygiidae. Among other things, Arkangelsky regards _Yasykovia_ Efimov 1999 as a junior synonym of _Paraophthalmosaurus_.

Moving onto more talks?

GASTROPODS

Stick with me here.

Dave Martill and Mike Barker: The dinosaur and the snail.

Several Wessex Fm dinosaur bones from the Isle of Wight have strange little rounded bodies arranged in patches on their surface. The bodies are all the same size and arranged in crude rows. It turns out that they are gastropod eggs with embryos still inside. So, Cretaceous gastropods were using dinosaur bones as nesting substrates.

PARAREPTILES

Susan Evans: The Lower Triassic ?lizard? _Colubrifer_: a reassessment.

_Colubrifer_, described in 1982 by Carroll as a reduced-limb squamate perhaps ancestral to some of the later reduced-limb groups, cannot be shown to be a diapsid. Carroll?s interpretation of the skull elements is questionable and what he regarded as the dorsal midline of the skull is suspect. Reidentification of some of the skull elements showed that the skull was parareptile like, specifically like _Owenetta_, and the proportions of the skeleton matched described specimens of _Owenetta_ exactly. Robert Reisz said that he had independently come to the same conclusion while looking at _Colubrifer_ for a recent review.

LEPIDOSAUROMORPHS

Paul Barrett: A helodermatid-like lizard from the basal Cretaceous of England.

As part of the review of the Purbeck fauna, Paul was asked to look at the ?granicones? previously described as part of _Nuthetes_, _Echinodon_ or a stegosaur. Histological analysis, carried out by Jane Clarke, shows that the elements have similarities with the osteoderms of thyreophorans, squamates and anurans but they are clearly not from crocs or turtles. Closest similarity is with the cranial osteoderms of helodermatids and this appears to be the best identification for the elements. If correct this is the earliest helodermatid lizard to be reported and the first from the UK. Showing cladograms that include Gao and Norell?s Monstersauria always incites a few sniggles.

Torsten Rossman: Short review of the Middle Eocene (MP 13) lacertilian fauna from the fossillagerstatte Geiseltal near Halle (Saale), Germany.

Corytophanid iguanians are well represented at the locality (not sure what this means for biogeography: another group shared between Eocene Germay and S. America? I?m not aware of corytophanids from elsewhere) and there are also possible skinks and lacertids, a cordylid and both glyptosaurine and anguine anguids. The corytophanids are part of the messelosaurine subfamily, erected by Torsten in _N. Jb._ recently.

Garth Underwood: A history of snake retinas.

Booids, viperids and colubrids have different retinas but the colubrid type appears to have been derived from the viperid type, not the other way round as Wall, encouraged by the snake systematists of the time, concluded. This work is in agreement with Underwood?s other work: all suggests that venomosity was primitive in caenophidians and that colubrids are not primitive in lacking venomosity and grooved teeth ? they are derived. Structure of the snake retina cannot be derived from any lizard retina.. dammit, should have asked an intelligent question about amphisbaenians:)

SYNAPSIDS

Robert Reisz: Patterns of amniote diversification during the Late Palaeozoic.

Essentially, ?synapsids did it first?! Cladograms of all Palaeozoic amniote genera show that both synapsids and reptiles underwent three or more major events of diversification but, on each occasion, synapsids evolved more taxa than reptiles. This is not due to a size bias or misrepresentation due to environment. While reptiles are very abundant at some localities (e.g. Bromacker quarry in Germany where there are loads of procolophonids) they are at a lower diversity than synapsids. Slides shown of the new ?bipedal bolosaurid, the earliest known facultative biped (posters at SVP in 1997 and 1999, was also covered in _Nat. Geo._)

Ian Jenkins: Gorgonopsid ecomorph niche-filling after the P-Tr extinction by ?aeleromorph? moschorinid therocephalians: a finite element approach.

As it says. Moschorinids have robust, well-braced palates and felid-like incisor arrays and effectively mimic the earlier macropredatory gorgonopsids and appear to have replaced them ecologically. One problem is that gorgonopsids lived alongside large prey animals like giant dicynodonts and pareiasaurs ? in the faunas from which moschorinids are known there are no large prey animals.

I have a speculation. Could it be that, rather than attacking large animals, moschorinids were either (1) biting armoured prey (e.g. small parareptiles) or (2) biting the skulls, rather than the bodies, of small/medium-sized prey? Jaguars (_Panthera onca_) are reported to have the most robust skulls of any extant felid and (1) they eat armoured prey like caimans and turtles and (2) kill medium-sized prey, like capybara, by biting through the orbit or braincase. Unlike moschorinids however, jaguars often have significant tooth wear to the extent that some individuals have their canines worn down to broken stumps. Oh well.

Percy Butler: Another look at haramiyids.

A good review of haramiyids: apparently they are now known from Tendaguru and thus survived for longer than thought. _Theroteinus_ has three rows of cusps on molars and appears not to have the longitudinal chewing present in other forms. MTBs and haramiyids appear to have similar premolars and Butler argued both that haramiyids should be allied with MTBs and that both are very basal mammals that should be recognised as the Allotheria. This is the old school view of course.

Sanchez-Villagra argued that argyrolagids were part of the Paucituberculata, Janis covered the evolution of pacing locomotion in camels.

That is that, I?ve now covered everything I wanted to. And, yes, it should have been ?dinosaurs and mice and the twain?.

"Right after we're married, and I mean >right< >after<, they turn us into statues"
"That.... is............. fascinating"

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