What drove bird evolution?

Why don't we use the numbers present in the article you posted a scan of? Or are you doubting the accuracy of them?Given that the eagle has a wingspan of 8 and the Teratorn has a wingspan of 25, it would have (25/8)^2 = 9.7 times the surface area. Okay so far?A male bald eagle weights about 13 pounds while a Teratorn weights 170. This is 170/13 = 13 times the weight.So, either some numbers are wrong in the article, or those guidelines won't apply here. Did the Teratorn really need wings that are trice as thick? Did it need a middle body that is much larger to eat whatever it preyed on?This message has been edited by Melchior, 07-15-2004 09:34 PM

[joke]Of course, as you can clearly see from the picture, that crane is only a few centimeters high![/joke]In case someone is doubting his numbers, I figure I'd look it up and provide some more details than just "millions".One of the (maybe THE largest) cranes currently in commersial use is the K-10000 crane developed in the 80's. It can safely handle a load of up to ~16 million foot-pounds (or ~106M Newton-meters for us normal people). Several of these cranes have been used for years.Sources:Largest tower crane in the World - 100 tons at 100 meter radius - Diagram over crane as well as details
HTTP 404 - page not found - General history of developers of the crane
http://ecolu-info.unige.ch/archives/ceeman02/0068.html - One crane for sale, also includes a photo of an erect crane