RE: On the Issue of Sprawling Dromaeosaurs

[MariusRomanus@aol.com]

Despite the expected attempts to sidetrack and manipulate the argument (be them 
intentional or not) in the exact same ways I explicitly stated to have occurred 
every other time this subject has been discussed, I'm quite glad that most of 
my central idea made it through unscaved. But, just so that there is no 
confusion, I'd like to suggest rereading my post if it is believed that I was 
merely restating the laterally orientated femora hypothesis. 

What I actually said was this: > Take the femora and move them forward as if 
the animal is sitting in a nest. Then roll the femora so the lateral aspect of 
the shaft turns to point in a dorsal direction. This would have the effect of 
orientating the distal condyles so that they pointed in such a way as to allow 
the tibiotarsus to extended outwards in a lateral manner. This motion also has 
the effect of orientating the leg feathers in the direction of the airflow, 
which is precisely where we want them if they are going to be involved in any 
sort of flight-related activity. < 

My hat is off to Ralph Miller and his response with a picture of a wren which 
seemed to say a thousand words. Here it is again: 

http://friendsofsherwoodisland.org/Photos/Hand/Land/AJH-marsh%20wren%20supersp 
lit.jpg 

In a reply to the above, Christopher Collinson posted the following: 

>>  First this wren is not sprawling in the same manner that is associated with 
>> the four wing sprawl hypothesis, where the femur would rotate forward and 
>> up/out. In fact the femur as well as the tibia occupy near normal positions, 
>> the knee is probably directed a little inward from its normal position so 
>> that the ankle is oriented as far out ward as possible. Secondly I think 
>> there may be a bit of an optical allusion at play here, making the right 
>> ankle appear closer to the lens than it really is. << 

On the issue of optical illusion: 

I see from your comment that you believe there was an attempt to state that the 
picture of the wren shows the same exact posture as I stated in my post. This 
may have been what was implied, but I simply do not see this picture of the 
wren as stating that at all. What I do see is evidence indicating that the back 
and forth scissor-like motion of the 
hind limbs, with all its implied restrictions, is in no way the gospel as 
viewed by some. It's safe to say that absolutism just flew out the window. Many 
birds that climb have the ability to laterally extend their lower legs to some 
degree. And just so we have at least one other example supporting this, here 
are multiple photographs of bitterns that might be of some interest... 

http://www.tpwd.state.tx.us/nature/birding/austin_birding_sites/images/area3_l 
east_bittern.jpg 

http://www.greglasley.net/Images/lbittern1.jpg 

http://www.birdingamerica.com/Delaware/Delawareimages/pmmarshsong.jpg 

http://www.dnr.state.wi.us/org/water/fhp/papers/p2/img006.jpg 

http://www.hkbws.org.hk/graphic/ybittern.gif 

http://www.valdosta.edu/~bergstrm/lebi5_la.jpg 

http://www.pbcwater.com/wakodahatchee/images/gh_leastbittern.jpg 

http://hsk3.home.att.net/lebi.htm 

http://www.nenature.com/Images/LeastBitternLDD.jpg 

What is so profound about these birds in relation to my argument is that these 
animals are showing a slight lateral orientation of the tibiotarsus that is 
used to set up an even greater lateral orientation of the tarsometatarsus. This 
is perfect support for two very important ideas central to my argument. One is 
the fact that variations occur that can be selected upon. Two is that this 
particular posture was most likely induced by the bird's environment, much in 
the same manner that the arboreal hypothesis suggests selective pressure that 
would have been applied to the basal dromaeosaurs in question (something that 
Ralph Miller also noted). I am also betting that there is little in the way of 
alterations to the anatomy that facilitates this ability when compared to most 
birds of similar sizes and overall build. This can be tested rather easily with 
a little comparative analysis, though I admit the results have little impact on 
the issue. 

Also, I did not state conclusively that these dromaeosaurs possessed the 
ability to laterally sprawled or not. What I did do was ask for exactly what 
prevented them from 
doing so: 

> If anyone really sees the need for a massive change in the shape of the 
> femoral head that would be required in order to allow this type of motion, 
> please speak up and explain. Is a radical manipulation of the soft tissues 
> also required in order to facilitate this movement? Again, if so, please 
> explain. Do we really need a massive change in the insertion points and in 
> the arrangement of muscles in the hind limb? Again, explain if this is the 
> case. And most importantly, based upon the preserved bones, what do we 
> actually know when it comes to the soft tissues of the hind limbs of these 
> basal dromaeosaurs that would spell doom to this idea? < 

These questions were really never answered, and as such, they remain on the 
table. To state them another way, do you believe that "tens of millions of 
years" of evolution is required to go from what we see in the wren and bittern, 
to a laterally orientated tibiotarsus and tarsometatarsus in the ancestors of 
our basal dromaeosaurs? If so, please explain why. And while I'm at it, what 
anatomical differences are allowing some birds to laterally extend their legs, 
while others cannot? If someone knows, please be specific, since these 
differences are obviously oh so profound. Also, who seriously thinks that it 
took "tens of millions of years" for these birds to develop this ability? 
Restating flaws in an older hypothesis, attacking the lack of evidence for the 
older hypothesis, giving "just so" answers, or going off on some tangent 
instead of answering my actual questions, is simply avoiding the real issue. 

A claim was made that a soft tissue's purpose is only to restrict joint 
movement. This is indeed the case in many ways, but the suggestion taken as it 
was stated is quite misleading. If one has a joint that is deep, like many hip 
joints are in birds for example, the thicker the cartilage is, the more shallow 
the acetabulum becomes. This can, in many cases, free up the range of motion of 
the femur a great deal.  But, in giving more flexibility, it in turn makes it 
more prone to dislocation. What's being forgotten here is that soft tissues, as 
in ligaments and tendons, can be utilized as braces for a bony structure that 
would otherwise become easily dislocated without such support. Again, this is 
why I used the manus of *Archaeopteryx* (and the wrist joint of birds in 
general) as a key example in the first place. It is almost a less cruel version 
of "Arbeit macht frei", in which instead of "Work will set you free", 
restrictions that can be used like safety harnesses can set yo!
 u free...
 

Given the replies already received, saying that there is zero evidence in the 
fossils that prevents a sprawling posture from being possible after taking 
variations in the form of soft tissues into account, has yet to be sufficiently 
countered. 

Again, my whole point with all of this is that the conclusion that the issue of 
the lateral sprawl is an open and shut case is highly premature. Instead, it is 
really just the glimmer of old dogma intruding into what is supposed to be a 
science. Harsh words, but truthful words nonetheless. 

Kris 
http://hometown.aol.com/saurierlagen/Paleo-Photography.html