II CLPV talk summaries: Day 1

[dinoboygraphics@aol.com]

Hello fellow DMLers,

Greetings from beautiful Rio de Janeiro!  I thought I?d post some 
summaries of the talks for those of you who are interested.

First, a few general observations:  The coffee here is fantastic!  It 
can best be described as a really strong cup of espresso.  The food at 
the conference is far, far better than what is normally served at SVP.  
I understand that SVP has a different set of funding issues for their 
annual meeting, so no offense intended to the organizers, but 
compliments really must be paid to our Brazilian hosts for both the 
quality and the sheer quantity of the food they provide.  While 
everyone here is very friendly, and most speak at least some English, 
on the first day a large number of talks were given in Portuguese.  
Since I am only semi-competent at Spanish, and Portuguese pronunciation 
baffles me, I cannot provide many details from those talks.  With that 
caveat, on to the talks from Day 1:

Day 1: Wed. the 10th.

I missed the talks until 11:00, as I was putting the finishing touches 
on my own presentation.  My apologies to lepidosaur phylogeny fans, as 
I understand there was some cool stuff.

Bruce MacFadden gave a very convincing talk using tooth isotope ratios 
to throw doubt on the traditional dichotomy between inferred eating 
habits of high-crown toothed mammals (usually interpreted as open 
grassland grazers) and low-crown toothed mammals (forest browsing).  He 
showed a Florida paleocommunity with six genera of horses, and despite 
all of them being hypsodont (high crowned), only two genera showed 
tooth isotope ratios consistent with exclusive grassland grazing.  Two 
of them were consistent with exclusive forest browsers, and the other 
two showed intermediate isotope ratios.  He speculated that the same 
thing may be happening in South American faunas that are overly 
abundant in toxodont taxa.

After lunch Michael Benton gave an hour long overview of his work in 
Russia, which has the goal of delineating a good terrestrial P/T 
sequence there.  It was filled with a number of humorous anecdotes, 
including a photo of an enterprising individual who was selling 
fermented mare?s milk in the countryside of western Russia.  The 
scientific progress report from the project is that they have a good 
enough isotope series to corroborate the classical Russian location of 
the P/T boundary. They hope to get some radiometric dates, and between 
those and sedimentological sampling establish whether they have a 
continuous terrestrial series or if there is an erosive contact 
present.  A continuous section will let them evaluate hypotheses about 
tetrapod faunal turnover at the P/T boundary.

Ralph Molnar gave an amusing talk about an incomplete pterosaur skull 
he is describing with Richard Thulborn.  Apparently they sent the 
manuscript to a journal (which he did not name), who then lost it for 
almost two years.  After it was found and sent back, the authors (who 
apparently didn?t want to be outdone by ?mere? editors) lost it 
themselves for another 18 months, at which time they had both retired 
from their positions.  So a few more years pass, and they decided to go 
ahead and publish the specimen here at II CLPV, since they ?didn?t have 
anything better to do?.  It is apparently an Early Cretaceous 
pterodactyloid from Queensland, but there aren?t enough diagnostic 
characters to say much more about it.

There were some interesting looking talks in Portuguese about South 
American avian faunas, and (yay!) one in Spanish about using 
comparative morphometrics to estimate the feeding preferences of 
extinct penguins.   The punch line was that there was at least as large 
a diversity of feeding habits amongst the extinct penguins she examined 
as there is today.

One of Alexander Vargas? students (sorry, the abstract volume only 
named Vargas, and my notes appear to be inadequate in this regard) gave 
a talk in Portuguese about the developmental identity of the manual 
digits in extant birds.  Drawing upon the abstract, and supplemented by 
the slides (both of which were in English), I am happy to relay that 
genetically speaking bird fingers are indeed 1,2,3, not 2,3,4.  In 
tetrapods Hoxd12 is not expressed in digit 1, and digit 1 is the last 
to express Hoxd13.  Well, the condensate that becomes the equivalent of 
digit one (by dinosaur morph standards) follows this gene patter.  
There may well have been a homeotic shift in condensates such that the 
genes from digit 1 are expressed in condensate 2, but that of course is 
completely consistent with the theropod origin of birds.  Not much of a 
surprise, but still nice to see established empirically!

Terry Jones delivered a paper by him and the Rubenite clan.  The gist 
of it was that feathers usually fossilize when the bacteria attempting 
to break down the cartilage autolithify, creating a microscopic cast 
around the feather.  They SEMed a few specimens from China of different 
birds and non-avian theropods, and concluded that while 
Sinornithosaurus does indeed have feathers, that Sinosauropteryx and 
Beipiaosaurus do not.  I got the impression that very few people in the 
audience were convinced by the data.  For starters, they did not have 
good enough sampling of Yixian theropods.  For example, they did not 
test the fur-like feathers of Sinosauropteryx, Microraptor, or 
Caudipteryx; even though they accepted that the contour feathers were 
actual feathers (duh!).  Nor did they test scales from, say 
psittacosaur specimens to see how keratinous structures that were 
histo-chemically different from feathers would preserve.  In their 
defense, Terry said they did not get much choice in their samples, as 
that call was made by Chinese authorities.  I sympathize with the 
difficulty that arise from working with foreign specimens, but they 
should never have made the conclusions they did with the samples they 
were afforded.  For example, they claimed without the slightest bit of 
supporting evidence that not only is ?dino-fuzz? not feathers (which 
itself is defensible), but that they aren?t even keratinous (and, they 
conclude, most likely collagen).  In the absence of comparative 
taphonomic data to show how other keratinous structures preserve (e.g. 
scales or the dino-fuzz of theropods with morphologically modern 
feathers) this is an utterly baseless claim.  At best this is evidence 
that the insulatory structures that comprise ?dino-fuzz? had a 
different molecular make-up than fully modern feathers, which would not 
be a huge surprise (evolution often proceeds on both histological and 
morphological levels simultaneously).  At worst it was a waste of time. 
 Terry, however, is a great guy, and I don?t mean this as a personal 
attack on him in any way.

I gave the next talk, which some of you already know was on the origin 
of avian flight.  I made a number of methodological critiques on 
previous attempts to understand the origin of flight, which I won?t 
bore you with here unless someone is interested enough to really 
warrant that much space (it?ll be in the paper though!).  I did make a 
rigorous comparison between extant ?analogs? for arboreal gliding 
organisms and theropods, including a reconstruction of the pelvis and 
femora of Microraptor (based on specimens described by Hwang et al.) 
that show Microraptor could not laterally spread its hind limbs.  I 
also mapped characters against recent cladograms to show that the 
characters associated with arboreality in birds show up very late, much 
later than the avian flight stroke and aerodynamic feathers.  Hence, I 
concluded that feathers and the aerodynamic surfaces they create 
(though not necessarily powered flight) are more likely to have evolved 
in terrestrial cursors.  I also discussed WAIR.  I pointed out that 
successfully engaging in wing assisted incline running requires a 
derived form of the avian flight stoke (i.e. laterally facing glenoid, 
morphologically modern feathers, and the musculature to flap them with 
sufficient force) to pull off, so WAIR is unlikely to have provided 
selective pressure leading to the origin of those structures.  It may, 
however, have played a role in the later transition to powered flight, 
the transition from terrestrial to arboreal habitats, or both.

I know many on the list would disagree offhand, but I hope when the 
paper comes out you will be convinced that there is only the weakest of 
support from comparative functional morph and from phylogeny for the 
classical trees-down view of avian evolution.  Despite the intuitive 
appeal, wings themselves and the avian flight stroke appear to have 
shown up without an arboreal gliding phase.  Whether the actual 
transition to powered flight occurred in the trees may be a different 
story.

Willem Hillenius gave the last talk of the day (once again coauthored 
by the whole slew of Rubenites).  Ironically, I don?t disagree with the 
conclusions in his talk, although I greatly disagree with some 
implications in his abstract and throughout much of the presentation.  
His conclusion was that based on characters of the sternum and pelvis, 
pre-ornithurine birds (and non-avian theropods) did not achieve the 
same level of respiratory capability that ornithurine birds have, and 
he said explicitly that ?he couldn?t say for sure whether they had 
ectotherm oxygen consumption rates, sub-avian rates, or something in 
between?.  That is perfectly acceptable, and totally out of line with 
the abstract?s indefensible false dichotomy between ?avian endothermy? 
and ectothermy.  Extant ornithurine birds have by far the highest 
oxygen consumption rates of all tetrapods, and I don?t doubt for a 
moment that more primitive birds (and all non-avian theropods) had 
lower oxygen consumption rates.  That in no way is positive evidence 
for ectothermy amongst those groups, and as I said, Willem did not in 
fact conclude it was.  The abstract title and much of the talk, 
however, gave the strong impression (and I talked to a number of people 
to get the opinions of others) that pre-ornithurines were ectothermic.

After the talks we enjoyed a lovely reception at the Museu Nacional, in 
which servers appeared to compete to see who could stuff the most 
appetizers and/or alcohol into paleontological stomachs in an evening.  
A great time was had by all.

There were some fantastic talks on early dinosaur evolution today; I 
will post those as soon as I have time to get them typed up.

Scott Hartman
Science Director
Wyoming Dinosaur Center
110 Carter Ranch Rd.
Thermopolis, WY 82443
(408) 483-9284

www.skeletaldrawing.com