SVP 2K review, part I

I'd like to add to the chorus that this was one of the best meetings I've ever been to! Met a few list members who I hadn't before, had a good time, got the traditional post-SVP cold/sinus infection (and I'm not the only one...).

This wasn't a talk with any real outstanding new specimens presented (at least none I saw), but that doesn't mean that there were lots of extremely interesting talks & posters.

In the Plenary Session, Sumida et al. detailed the upland German Early Permian fauna (that contains _Eudibamus_, actually). An extremely interesting bit for those interested in predator/prey ratios: _Dimetrodon_ (the only sizable predator known there) is extremely rare, while the main large herbivores (_Diadectes_ and another, as-yet-unnamed diadectomorph) make up something like 95% of the fauna. Kind of challenges the idea of a high pred/prey ratio for the Early Permian, at least for this assemblage...

Main et al. described how many features of the plates of _Stegosaurus_ are constructional artifacts (i.e., are the natural consequence of the method of growth), and suggested that display would have been the primary function. Thermoregulation, if used, would have been a secondary function.

My talk: lots of cladograms. New news (somewhat rushed through): support for Tyrannosauridae + Ornithomimosauria is greatly reduced, and I suspect the next iteration will find Tyrannosauridae outside Maniraptoriformes; Troodontidae winds up in two equally most parsimonious positions: as the sister taxon to Dromaeosauridae OR as the sister taxon to Alvarezsauridae (!), together the sister group to _Archaeopteryx_ plus later birds.

John Alroy's simulation of the extinction patterns of Pleistocene mammals was interesting: he showed that using realistic parameters for human hunting ability and growth rates, you can wipe out the North American megafauna very rapidly without any appeal to climate change.

Speaking of computer simulations, several talks put these to good use. Bob Walters et al. showed the use of virtual skeletons in doing life restorations, based on the Smithsonian's _Triceratops_ project. Don Henderson's talk on ornithopod locomotion used reconstructions of walking theropods and ornithopods to investigate the increasingly bird-like digit angle in larger ornithopods. Emily Rayfield's Romer Prize session used Finite Element Analysis to reconstruct the bite forces in _Allosaurus_: turns out, not surprisingly, it is a lot weaker-jawed than _Tyrannosaurus_, and in fact the cranium can absorb greater impacts if the mandible wasn't used. Emily suggested that _Allosaurus_ may have used a hatchet-like attack, and then used the slender mandible only in feeding: this is also the suggestion of Bakker in the Gaia volume.

Galton & Upchurch presented an interesting history of the identification of the three sacrals in prosauropods, and how in some it is a dorsosacral, sacral 1 & sacral 2, and in others it is sacral 1, sacral 2 & a caudosacral. Galton also showed how some workers had moved a bone from the rear of the sacral series to the front (or vice versa) depending on their preconceptions.

The team of Josh Smith, Matt Lamanna, Ken Lacovara, Jen Smith, and various colleagues (including Peter Dodson) had a couple presentations concering the U Penn work in Bajariya Oasis, Egypt. Their big (literally!) news is the discovery of a titanosaur sauropod rivalling _Argentinosaurus_ in size, and comparable in anatomy and stratigraphic position. They observed that the likely local environment was a mangrove (which, as Lacovara pointed out, is technically a type of environment rather than a species of plant: there have been mangrove environments long before the evolution of red, black, and white mangrove trees!). In the words of Thulborn and Farlow, back to the swamps!! (They also did a calculation showing that, in the types of sands involved in the channels, a giant sauropod would not get mired at all: this stuff can support hotels!).

Brochu described "Sue": weird and wonderful stuff. In the words of Firesign Theatre, "everything you know is wrong". Forget just about every interpretation of the sex, pathologies, etc., that was made in the preliminary reports of ten years ago: they were preliminary, after all, and only now has the detailed work been done.

The little Madagascan theropod with the vaugely spinosaurid-like jaw that Sampson, Carrano & Forster had been showing around at SVP in years past turns out to be a little abelisauroid. Additional material suggests that it forms a clade with Argentine _Noasaurus_ and Indian _Laevisuchus_: in other words, it is a noasaurid. Multiple specimens are known.

Speaking of abelisauroids, Coria et al.'s new abelisaurid is magnificent!! It is very close to, but more primitive than, _Carnotaurus_. The forelimbs are in great condition, and there seemed to be no signficant carpals (if any): it looked like the metacarpals contacted directly to the forearm!

Alan Gishlick (presenting for Gauthier & Gishlick) has re-examined the hand of _Compsognathus_. It turns out to have a relatively typical primitive coelurosaur hand: very short mc I, long digit I, robust mc II, slender mc III. He could not be certain if there was a third digit, but the end of mc III suggests that one was present. He did show how confusingly things are arranged on the specimen due to postmortem movement, so that the various interpretations of Huene, Ostrom, Gauthier & Rowe, and others are understandable.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland         College Park Scholars
                College Park, MD 20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone: 301-405-4084    Email: tholtz@geol.umd.edu
Fax (Geol): 301-314-9661       Fax (CPS-ELT): 301-405-0796