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Armour Symposium Recollections



Good day,
Well, I have returned from the Armour Symposium at the Field Museum, and was 
very impressed with all of the speakers.  I was also very impressed with the 
large turnout of listmembers, as about 15 DML members must have been present 
(if not more).  I finally had the chance to meet a lot of you out there, and 
assign a face to some of the people that I have met through this list over the 
years.

Anyway, as I said, I was very impressed with every talk, although I was a bit 
disappointed that Emily Rayfield had to cancel.  John HutchiNson (I'm a 
journalist that can spell) opened the day with an intriguing talk on dinosaur 
locomotion.  Basically, he recounted his disproving of the hypothesis that 
Tyrannosaurus could run at speeds of 20 miles an hour (which has been said in 
the literature numerous times).  Instead, he said that Tyrannosaurus likely 
couldn't run at all (meaning there was no aerial phase to its gait), and its 
top speeds were likely in the 9 mph range.  

Matt Carrano followed with a talk on the size and scaling in large theropods.  
He described the four major lineages (Abelisauridae, Allosauridae, 
Spinosauridae, and Tyrannosauridae) and explained their phylogenetic 
relationship and unusual features of each group.  

Harvard's Leon Claessens gave what I thought was one of the better talks, as he 
discussed the function of gastralia in theropod ventilation and respiration.  
Basically, he described gastralia as an accessory brething mechanism that 
operated in concert with a sternal aspiration pump.  To me, the function and 
structure of gastralia are interesting because, although they are plesiomorphic 
for tetrapods as a group, only theropods and prosauropods (among dinosaurs) and 
crocodiles and Sphenodon (among extant tetrapods) possess them.

Elizabeth Rega, a doctor, then discussed the pathologies of Sue.  She dismissed 
the fact that Sue suffered from syphillis, but gave evidence for osteomyelitis 
of the left fibula (NOT a broken bone!) and healed osteomyelitis of the right 
humerus (the proximial end).  

After a lunch break Phil Currie discussed the giant coelurosaurs from South 
America and Alberta.  He talked a bit about how one can tell Albertosaurus from 
Gorgosaurus (although it is very difficult, even from skull elements).  Then, 
he talked about Giganotosaurus and the new large theropod from Alberta.  He 
said that the new specimens are less derived and more primitive than 
Giganotosaurus, which means that they are not indeed members of the genus 
Giganotosaurus (as many on the list have suggested).  However, a paper on the 
specimens wil not be published for some time.  

Our own HP Thomas Holtz gave what I thought was one of the two or three best 
talks on the evolution of tyrannosaurids.  He specifically discussed two 
enigmatic taxa, Stokesosaurus and the new Eotyrannus.  For the sake of not 
wanting to skew his data, I will let HP Holtz discuss more about his research 
when he returns from Chicago.  

Following HP Holtz was HP Chris Brochu's talk on the systematics and 
phylogenetics of Tyrannosauridae.  He discussed aublysodontines, and dismissed 
them as too fragmentary to be included in good analyses.  He also voiced his 
opinion that aublysodontines are nothing more than immature specimens of larger 
tyrannosaurines.  In addition, he said that a sister taxon relationship between 
Tyrannosaurus and Daspletosaurus is as parsimonious as that between 
Tyrannosaurus and Tarbosaurus.  Finally, he made his case for tyrannosaurids 
being closer to birds than Allosaurus and kin, but also said that they occupy a 
very basal position within the coelurosaurs.  

AMNH and soon-to-be FMNH dinosaur paleontologist Peter Makovicky then gave a 
discussion on "is there more to large theropods than size alone?"  In 
particular, he discussed CHI analyses and other ways of producing a better 
theropod family tree.  

Finally, the last talk of the day was given by Hans Larsson.  This was another 
of my favorites.  He discussed the loss of digits in large theropods, saying 
that digit loss progresses as theropods evolve, and digit loss is permanent (in 
other words, no large theropod re-evolved digits).  Specifically, he made a 
case for a two-pronged digit loss: the primary loss of the digit location and a 
secondary loss of the digit itself (after the digit begins to form).  This is 
one particular study that I would love to see a new paper on.

Well, now that my ranting is nearly done, I would like to press HP Brochu and 
Dr. Carrano to produce a symposium volume.  And, I would also love to have 
another dinosaur symposium at the Field next year.  

I welcome any comments from the list or anybody who also attended!

Steve

P.S.: Yes, there were a few media mistakes in that article, but, hey, who can 
expect a PERFECT article from any newspaper?

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Steve Brusatte-DINO LAND PALEONTOLOGY
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