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Swimming, functional morphology, cladistics, etc. (long)



Here's a note I somehow managed to send only to Mickey, so I'll try again
and add a few things in addition

Subject: swimming and running speed and functional analyses

Hey guys, I wanted to thank Chris for his interesting notes and mention
another case where we know very well the swimming speed of a paleo
beast. In one of the most amazing papers Daniel Fisher did a detailed
analysis of the functional morphology of swimming in the horseshoe crab
Limulus and was able to document the swimming speed and angle from
the air-water interface (they swim upside-down by the way) that
Limulus swims and how the shape of their carapace gereates
hydrodynamic vortices that are shed at a certain rate - which just
happens to be the rate at which the crabs move their legs when they
swim and thereby optimizes their energy expenditure while swimming.
Incredibly neat and wonderfully done. Then, using the shape of the
carapace in the Jurassic horseshoe crab Mesolimulus and running water
across it, he was able to deduct at what angle and at what speed it
swam. It is an exquisite study which Niles Eldredge called ineluctable
(ineluctible?) in his review of the volume (the Fossils and Strata volume
on trilobitomorphs). Meaning, you can't argue with it it is so sound
logically. It's one of the best paleo functional studies ever done and is
part of a suite of papers Dan did on horseshoe crabe which
demonstrates why their genal spines look exactly the way they do - a
combination of settling dynamics and righting capabilities (they land
upside down as well), and documenting why the Pennsylvanian
horseshoe crab Euproops probably had significant subaerial activity.
They demonstrate how to do such work. If anyone wants the refs, I'll dig
them out.

   Anyway there is amazing power in a properly structured functional
analysis of this sort - more than most people understand. However, I
suspect the discussions on the origin of flight are structured totally
wrong to answer the questions about the origin of birds that people are
trying to do. Mostly, they equate to imaginative stories and have little or
no utility to disprove any origin. The only effective approach so far in the
question is the phylogenetic approach, which pretty much destroys all bu
the theropod origin at the moment. Functional analyses after the fact and
using these phylogenies can then do well to use the available power of
the functional approach to see what might have happened but they are
not all that useful for random exploration.

And now for some additional comments on George's  comments on
cladistics.

First, although cladistics can at times be infuriating and some of its
proponents a pain in the buttocks, I think those who continue to fight it to
the death are being very unreasonable given that there are no
reasonable alternatives at this time. Traditional phylogenetic techniques
did not work all that well and resulted in massive numbers of unnatural
and waste-basket taxa. When I grew up, for example, one of the largest
groups of dinosaurs was defined by the fact that they had a basic hip
structure that, if taken as a single character, would have included myself
and most of the rest of the tetrapods in the group. It gave rise to amazing
wastebasket groups such as the trilobitoids where confusing taxa could
be swept away under the rug, etc. Phenetics is actually very useful in
some contexts but is not a reasonable way to develop phylogenies. More
useful for superimposing phenetic analyses on top of established
phylogenies in a variety of contexts.

 That gives us cladistics as the way to go with what is available now.
The vast majority of evolutionary scientists are trying to figure out ways
of improving cladistics, or finding a better way. It's tough. You can also
use a solid phylogenetic analysis as a strong basis for doing a broad
spectrum of evolutionary studies. So, until a better alternative is really
available that is less art and can be repeated more easily from
researcher to researcher, cladistics it is. You don;t have to be hard-core
as some in using the method - some reject all fossil taxa, for example -
but there is lots of room to explore in the techniques. I think attempts to
better use morphometric analyses within cladistic analyses and the
dialog on using stratigraphic data are worthwhile journeys regardless of
the final conclusions. So, it's not perfect George, but you have no better
alternative - although certainly there is room for some flexibility in how its
done.

That's enough already from me here so I'll shut up.