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SICB Report, part 1 (long)



Howdy, all.

I'm back from the Society of Integrative and Comparative Biology meeting.
The abbreviation is SICB, pronounced (much to Farlow & my surprise)
"sick-bee".  Paul Davis actually began his talk with the joke "When I told
my colleague I was going to SICB, he said I should bring it some honey."  :-)

First, some practicalities about the hotel, which is also the hotel of this
year's SVP meeting.  Nice location (right along the 16th Street mall, 2
miles of pedestrian walkways, shops, restaurants, etc.), fairly inexpensive
restaurant in the hotel (although service could be faster).  BUT, if you
give a talk in the big ballrooms, the ambient light is a bit high, so plan
slides with a lot of contrast.

So, why was I at SICB.  Well, since I was there, and Farlow, and Greg
Erickson, and Phil Currie (who wasn't giving a talk) were all there, and Ken
Carpenter was in town, we COULD have had one kick-ass _Tyrannosaurus rex_
symposium!  However, I was part of a paper (given by Farlow, with co-authors
Gatsey, Hutchinson & Robinson) on dinosaur locomotion, which was part of the
symposium on the Evolutionary Origin of Feathers.

In part II I'll address talks that weren't part of that symposium, including
what I think was the best dino related talk at the meeting.  Too bad it was
the day AFTER most of the paleo folks had left.  Briefly, though, SICB is a
conference more paleo people should go to: lots & lots of experimental work
on functional anatomy & behavior.  You get to find out important things,
such as the fact that gliding in flying squirrels and snakes isn't at all
like the people involved in the origins of flight debate think it is...

Okay, the Feathers symposium.  It was originally planned as a functional,
developmental, and molecular look at the avian integument, but the discovery
of the feathered Chinese forms from Liaoning were used to bring in a lot of
paleo folk.  What we wound up with was a bunch of people who work on modern
feather development and structure, a bunch involved with paleo aspects of
feathers, and a few physiologists thrown in the batch.


The talks:
Peter Stettenheim gave a great overview of the diversity of modern feathers
(doubly good overview due to the constant malfunction of the slide machine).
It doesn't matter how much diverse you think feathers are: the reality is
even greater.

Walter Bock (who I had never met before: it turns out he had interviewed for
a job at U Maryland College Park before being hired by Columbia!!) gave a
talk which surprised me in many ways.  Instead of a review of the
pseudophylogeny method and scenario-based hypotheses (some of his classic
stuff), he instead pointed out that a) we don't have direct evidence of the
origin of feathers; b) what we do have is bones only for most of the
pertinent forms; and c) that it is extradorinarily difficult, if not
impossible, to test different scenario-based hypotheses for feather origin
against each other (e.g., insulation vs. display vs. flight) in order to
determine which should be prefered.  Agreed!!  I never thought I'd find more
to agree with in a paper by Bock than one by Dodson...

Due to non-interest or lack of time, several different people who were asked
to give the the token "dinosaur origins of bird" speaker position turned
down the organizers.  (No, they didn't ask me.  I would have done it,
though...).  The paper was given, somewhat reluctantly, by Stuart Sumida,
who admitted he mostly works on the other side of the amniote tree (basal
synapsids).  He made a few errors in his presentation (including the
spelling of _Protarchaeopteryx_ and phytosaurs as crocodylomorphs, when they
are only distantly related to that group) which will be corrected in the
published volume.  His paper would be a basic review for most folks on this
list, but some of the neontologists at SICB may not have been familiar with
the details.

Peter Dodson's talk, titled "Archosaur-avian relationships: review and
comment", focused a little bit on the first four words, and a lot on the
last.  Little in the way of scientific information that would be new to
readers of this list (although it might be new to some in the audience
there).  However, Dodson made it clear that he doesn't like cladistics (the
unofficial subtitle he mentioned was "cladistics sucks").  That's all well
and good, but I wish I could agree with his reasonings as to why cladistics
sucks.  In part he complained about the attitude of the practioners
(curiously in this talk and others "the practitioners" equals "Padian,
Chiappe & Norell", as if these three are somehow a majority when compared to
the rest of the people involved in dinosaur systematics, much less
systematics in general).  Okay, so these guys might be a bit (or more than a
bit) abusive in print: does that mean that the phylogenetic systematic
method is wrong?  Dodson also argued about the reductionist approach to
transforming everything to "0" and "1" (whatever happened to "2", "3", "4",
"?"...) as somehow ignoring the richness of life.  Funny, last time I looked
at Steel, Romer, or other classic precladistic work at systematics, I see a
list or table of characters described as present or absent in the forms
listed, but somehow this is more holistic than an appendix listing
characters and an accompanying data matrix?  Dodson also complained about
the phrase "nonavian theropods", which admitted wasn't coined until
cladistics, but has its analogies in pre-1956 phrases like "non-human
primates".  And, of course, there was the requisite complaint about
monophyletic taxonomy.  (Incidentally, Colin Patterson's idea of
incorporating all of Dinosauria in Aves was not completely tongue-in-cheek,
but reflects the differing taxonomic practices among actinopterygian workers
(who often prefer stem-based definitions for traditional names) and tetrapod
wokers (who prefer node-based)).

Most puzzling of all was his comment of the hegemony of morphology in
cladistics, and that genetics, biogeography, behavior, and stratigraphy
shouldn't be excluded.  This is puzzling since, outside of the small world
of paleontology, genes are THE dominant mode of doing cladograms (hey, they
were giving away free copies of an issue of Molecular Phylogenies and
Evolution, and there are a couple of other journals devoted specifically and
solely to this topic), and that the other three methods have been employed
to varying degrees of success.

(And, a side note: Dodson in his talk, and others during coffee hours and
elsewhere, also complained about people who just do cladograms and then stop
without doing more research.  First off, I find that a description that
doesn't map onto anyone in the field of bird origins (Norell and Clark do
excellent anatomical descriptions as well as cladograms, Chiappe has added
important information with regards to South American Cretaceous
stratigraphy, Padian has made many contributions to functional morphology
and to the historical study of paleontology, etc.).  Secondly, I had several
functional morphologist there tell me that they thought it was fine for some
people to devote most of their time to systematics: that way they could
devote most of their time to their own functional studies, while drawing
upon the analyses done by others.)

Harumph.

Derek Briggs & Paul Davis's paper (presented by Paul) was, for this
paleontologist, THE most useful and important paper in the symposium.  It
was precisely what I've been hoping for: a look at the processes by which
feathers are preserved in different lithologies and in different taphonomic
settings.  Note that the Solnhofen is different from most fossil feather
preservation, in that the Solnhofen is mostly impressions ("double-struck",
so that only one surface is preserved, both in positive and negative relief)
whereas bacterial-induced forms of preservation characterize the others.
Some really cool fossils were shown, including feathers with what are
probably fossil mite eggs, and some feathers in amber.  The authors have
discovered some taphonomic features which are unique to the decay process of
feather keratins, so we will now be able to search for feather homologues
independant of their morphology...  (i.e., a taphonomic test to see if
something could be a "protofeather", whatever that is).  As I've been
telling people before, fossilization is different that tossing a specimen in
formalin: you've got to look at the geology.

I missed the Maderson & others talk on the development of sauropsid
integument (I was off to see some other papers), but it discussed (among
other things) developmental data, the similarities and differences between
the total "reptilian" and avian integument, and the fact that there are
still some big gaps in our knowledge in living forms.

The next several talks had to do with aspects of modern avian scales,
feathers, and skin.  Sawyer et al. presented the keratin paper, which
featured (among other things) some featherless and scaleless mutant
chickens.  Menon et al.'s talk was on avian epiderman lipids, with
comparisons to those of "reptiles".  Homberger's talk was a look at the
functional and evolutionary microanatomy of avian skin, with some excellent
photomicrographs of the complexity of the muscles systems attached the
feathers.  She argued that feathers might not have evolved for flight,
insulation, or display (since other simpler structures work just fine for
these) but instead for streamlining the body while still terrestrial.
Unfortunately, she didn't explain what advantages such streamlining would
produce.  Wolf & Walsberg discussed heat transfer in bird feathers, both to
keep heat in or heat out, through radiative, convective, conductive, and
evaporative processes.

John Ruben's paper summarized many lines of evidence familiar to most
readers of this list (nasal turbinates, diaphragm breathing theropods,
_Sinosauropteryx_ fibres as internal collagen, etc.).  One new analysis
showed the difference in scaling (numerical, not integumentary) between
typical theropods and modern ground birds when total hind limb length was
plotted against trunk size.  (_Caudipteryx_ plots with the birds,
incidentally).  This is a plot I've wanted to do for a while, but I was
waiting to get a big enough data base on complete glenoacetbular
measurements of fossils before doing this (Ruben made do with
reconstructions).  He related this to Steve Gatsey's work on the differences
between "typical" theropod and avian hindlimb movement.  What Ruben did not
mention (although Steve did in his own talk in the Vertebrate Axial Skeleton
symposium, after most of the Feathers people had left the conference!) was
that the difference is not a dichotomy, but is a transition, correlated with
many associated changes in theropod anatomy from the basal condition through
basal tetanurines into coelurosaurs, through maniraptorans to basal birds,
and continuing changes well up into modern birds.  To show this one (albeit
interesting) scaling difference misses the gradational nature of the shift
in theropod locomotory history.

I missed most of Porter et al.'s talk on mechanistic models of feathers and
fur in heat and mass transfer, so I'll have to wait for the proceedings
volume to see.  Alan Brush's talk was very interesting, adding to his
DinoFest presentation, and showing how all the vast diversity of feather
types can all be formed by slight differences in development of a single
tubercular structure.  Variations in the development and timing of various
subunits of the follicle would produce everything from natal and adult down
to flight feathers to barbs to eyelashes and so on.  He also stressed that
any individual follicle produces different sorts of feathers throughout the
life of the bird.

Farlow et al. has some strange paper on dino (mostly theropod) locomotion.
When not being attacked by the microphone & its associated cords, or having
just about everybody miss his Groucho joke, Jim mentioned a) that
"cursoriality" is a poorly understood concept in modern animals, much less
extinct ones, but that we agree that arctometatarsalians seem to have more
of it than do most other nonavian theropods; b) to our surprise, modern
birds take shorter steps than did "theropods" of the same body size; c) like
Ruben, we found longer legs in modern birds than in Mesozoic theropods, but
that plotting just the "fuctional leg" (tibiotarsus + metatarsus) of ground
birds brought them right in line with non-avian theropods; d), etc., lots
more.  There will be lots of plots in that paper for all to enjoy.  We still
don't know why we were invited to give this talk at a feathers symposium,
but it was interesting nonetheless.

Alan Feduccia was not able to make it, so Nick Geist stepped in at the last
minute to fill in that spot.  Perhaps because of this, Geist had some
significant errors in his presentation.  For example, he (like a lot people
on all sides of this argument) polarized the debate as: Dinosaur origins of
birds = only found by cladisitics = bipedal ancestry = necessitates "ground
up" origin vs. some other archosaur = not found by cladistics = quadrupedal
ancestry = necessitates arboreal origin.  However, Ostrom (and Huxley, of
course) didn't use cladistics, yet it was Ostrom's papers in the 1970s which
convinced most workers on the dinosaurian origin (Gauthier and later workers
simply used cladistics to try and determine WHICH theropod taxon was closest
to birds).  More importantly, the figures used to illustrate the arboreal
hypothesis were from Chatterjee's 1997 book.  This is ironic in that a) the
hypothetical proavians in the figures shown are bipedal; b) they are
dinosaurs ("protodromaeosaurs" to use Chatterjee's phrase); c) the work is
based on a numerical cladistic analysis.  So much for the dichotomy...
Geist also mentioned, while discussing _Megalancosaurus_, that no theropod
had a posteroventrally facing foramen magnum.  This was a surprise to Currie
& me: I guess all those ornithomimosaur, troodontid, oviraptorosaur,
advanced tyrannosaur, etc., skulls that show that condition must not be
theropods.  Still, I don't know how much of this was due to Geist having to
fill in at the last moment.  He did have some new info on the hypopubic cup
of birds and its relation to breathing, about which we will here a lot more
in the near future.  Too bad he had left before Carrier & Farmer's talk on
archosaur breathing (more in part II).

Tarsitano et al.'s talk was on lots of different aspects of flight origins,
bird relations, and feather development, but concentrated on the latter.
Like Alan Brush, he argued that one of the key features of feather origins
(and later development) was a cylindrical follicle.

Larry Martin gave the last talk.  In it, he redescribed _Caudipteryx_ as a
flightless herbivorous ?enantiornithine bird and gave his interpretation of
the structures on the _Sinosauropteryx_ specimens.  He also mentioned that
he agreed that theropods had furculae (as did, in his interpretation,
_Longisquama_).  Martin suggested that birds were descended from forms at
the very base of archosaurs, perhaps from forms we would have a hard time
calling "archosaurian".  (Okay, so I didn't have the heart or stomach to
bring up the phylogenetic taxonomic definition of Archosauria... :-S  ).

During the formal discussion section, Phil Currie was given time to give his
interpretation of the _Sinosauropteryx_ integument.  He also clarified that
many people who accept the theropod origin of birds also accept a "trees
down" origin of flight.

There was little concensus on most major issues, either during the
conference or in the discussion.  Birds either evolved from some kind of
theropod or from something else.  Feathers either first evolved for
insulation to trap heat, or to reflect heat, or to streamline, or to protect
the body, or for flight, or for display, or for something else.

Some thoughts:
There was a lot of talk about what "the cladists" do.  When pinned down,
"the cladists" seem to be Padian and Norell and Chiappe, but other times it
seems to be more general.  I wanted to get up during the discussion section
and say "Hi.  My name is Tom, and I'm a cladist", but good taste got the
better of me...  Ruben expressed surprise when I told him that cladists
don't always agree with each other, and in fact often have disagreements.

(I also think it is unusual how people are labelled for, of all things,
their approach to systematics.  Sure I use cladistics for systmetics, but my
approach to historical geology is process uniformitarianism, to the motion
of the continent is plate tectonics, and to bivariate morphometrics plots is
Reduced Major Axis lines.  Why call me a "cladist" but not a "process
uniformitarianist", a "plate tectonicist", or a "Reduced Major Axist"?)

The funny (?!?) thing is that while many of the speakers were upset with
"the cladists" for dichotomizing everything, the very same speakers were
dichotomizing the field!  "The cladists" don't just do systematics, but (as
I mentioned above) do detailed anatomical work and/or functional morphology
and/or biogeography and/or stratigraphy and/or etc. 

Similarly, many of the same speakers talked as if "theropods" or "dinosaurs"
(both in the non-avian sense) all had one typical morphological condition,
and birds as another entirely different one.  In fact, there is a continuum
of form between the non-avian and the avian condition.  The great gap
between birds and other diapsids in the modern record begins to disappear as
you add fossil taxa.  All fossil birds do not show the full set of modern
bird features (huge keeled sacrum, short pygostyle, carpometacarpus, etc.)
but instead these appear at different points within bird evolution.
Furthermore, there are many characters which distinguish birds from other
living amniotes which we don't think of as "avian" because they have long
been known at various levels of the dinosaur hierarchy (retroverted pubis,
particular types of cranial and vertebral pneumaticity, reduced metatarsal
I, ascending process of the astragalus).  Until recently, furculae and
feathers were 'unquestionably' bird characters, but now the former (and
depending on the phylogenetic position of _Caudipteryx_ and
_Protarchaeopteryx_, the latter as well) are known to be more widely
distributed.

Ah, well.

In part II, other talks at the symposium.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:tholtz@geol.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661