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First Flying Dinosaurs Had Biplane Structure
unchiujar writes to mention a BBC article about the design of the first flying dinosaurs. These possible early ancestors of avians apparently resembled biplanes in many ways, with legs hanging down in a fashion similar to WWI fighters. The researchers who made this discovery use this to argue the 'trees down' model of flight evolution, but the article points out this design may possibly be a failed evolutionary experiment. From the article: "Dr Chatterjee, from Texas Tech University in Lubbock, US, explained that two lines of evidence had led the team to this conclusion. Firstly, the researchers argue, dinosaurs and birds move their legs in a vertical plane, not sideways as the tandem flight pattern requires. Secondly, the feathers on Microraptor's hind legs are asymmetrical; one of the two vanes that extend either side of the shaft is narrower than the other. Aerodynamically, the narrow leading edge of these feathers should face forward in flight, against the direction of airflow. This would have given the flying reptiles lift. "
I wonder if it might be better diagrammed with the bird using its legs in an "A" framed sort of way. Much like the V shaped stabilizers of the F117, only inverted. This would provide some lift, and stability in flight....
www.jmagar.com
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Not hardly. A biplane has no more lift-generating capability than a monoplane of the same total area...in fact less, because of interference between the two wings. The primary reason for a biplane is that by adding a few struts and wires, you can easily make a lightweight structure strong enough to carry heavy loads -- and you can do it with simple manufacturing techniques.
A secondary advantage is that a biplane has less overall wingspan than the equivalent monoplane. That means a lower polar moment of inertia in the roll axis which improves maneuverability.
The main disadvantage is that all those struts and wires hanging out in the breeze create something called intersection drag, which goes up rapidly as the airspeed increases. Yes, biplanes generally fly slowly -- because they have to, not because they can.
rj
The language isn't mechanically unjustifiable: a jaguar's morphogenesis stems from its genetic blueprint, and within its population that blueprint has changed through the process of evolution. In other words, an individual jaguar undergoes a process of being "made"-- starting with conception; on the species level a jaguar is also "made" via evolution. Ultimately when you see it in action, you say "it was made for the water." meaning, remarkably well-suited to the water.
The language is also justifiable for practical reasons: information wants to be anthromorphisized. Especially in a documentary, like you're talking about. Zoology documentaries are made for mass appeal, and so we can marvel at the (generally amazing) form and function of the zoological life that share the planet with us.
"inexact" speech doesn't appear in reputable textbooks and won't feature prominently in a technical conversation with a biologist if the topic is design and motivation. Casually (or excitedly) describing something within a documentary is totally different than pronouncing or formulating a definition or denotation (in which case possible misconstruals or implications would be more avoided).
Evolution is a "designer" in an abstract sense. We're human beings and we prefer to talk about things in figurative ways.
Giraffes & peacocks arise over timescales beyond our casual comprehension because of the mutability of genetic make-up across the generations, the divergence of populations, and physical environments that lend advantages and disadvantages to various biological forms. They don't just poof into existence, they have a dizzying set of ancestors and relatives like a lot of other animals, which are well detailed in the archeological record. Additionally the flashiness of peacocks is a common (but variably implemented) feature in the animal kingdom. As an interesting tangent about giraffes: the "eating food that's higher on trees" is a joke that was evidently originally created to deride darwinism rather than make sense of it, even though it still gets popularly cited as fact; a different and more empirical 'story' for the notable feature of giraffes-- long necks-- is that male giraffes are often observed to fight, by swinging their necks, even accomplishing killing blows, and the longer your neck the more tremendous your leverage. Within a small population the elimination of (shorter necked) male competitors would provide a huge boon to the representation of a long-necked giraffe in the local gene pool in subsequent generations. I'm no expert though and i've only heard this second hand.
Engage a credible biologist in a discussion-- or in publication-- instead of watching them in a documentary and you'll probably see a different presentation. All the same, "Design" (noun) commonly means "form", not "[Thing] That Was Made By Omnipotent Creator", and doesn't connote conscious intention. Drawing the inference that someone who uses the word "design" is making a theological claim and therefore isn't a "strict evolutionist" is absurd.