What drove bird evolution?

It's another square/cube thing. Weight is proportional to volume which is a cubed figure, while the ability to fly is ultimately ralated to surface area of wings, which is a squared figure.

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Recent studies in fact indicate that humans appear to have been fabricated using the same techniques which we ourselves are now starting to use in bio-engineering projects, which are anything but natural

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I think enough other people have explained that there is nothing "unnatural" about horizontally transferred genes. What they haven't mentioned is there probably aren't any in the human genome. Six months after the paper suggesting hundreds of such genes you get this: And as we sequence more and more eukaryote genomes it is becoming clear that the genes that Venter et al claimed only had ortohlogs in bacterial genomes are actually more closely related to eukaryotic sequences.

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

Adrien Desmond put it this way:

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"It would be a grave understatement to say that, as a flying creature, Pteranodon was large. Indeed, there were sound reasons for believing that it was the largest animal that ever could become airborne. With each increase in size, and therefore also weight, a flying animal needs a concomitant increase in power (to beat the wings in a flapper and to hold and maneuver them in a glider), but power is supplied by muscles which themselves add still more weight to the structure.-- The larger a flyer becomes the disproportionately weightier it grows by the addition of its own power supply. There comes a point when the weight is just too great to permit the machine to remain airborne. Calculations bearing on size and power suggested that the maximum weight that a flying vertebrate can attain is about 50 lb.: Pteranodon and its slightly larger but lesser known Jordanian ally Titanopteryx were therefore thought to be the largest flying animals."

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The "were thought to be" was, of course, before things like the argentinian teratorn and the Big Bend pterosaurs were discovered.

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http://www.bearfabrique.org/evorants/bioEngineering.html

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Amusingly the article you linked do actually gives you a clue about how evolution has probably worked on the vertebrates.

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from the article
The human genome probably does not contain significantly more genes than the fugu fish

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Not only are there not very many more genes, they all pretty much the same. If we are being rational that’s 400 million years of evolution and almost exactly the same repertoire of genes yet one is a small, inflatable fish that may be able to make people into zombies and the other is you. The difference between different vertebrates isn’t by and large the presence or lack of genes in their genome but the way in which they are used. Genes are turned on for longer in development, or alternative splicings are used to generate new functionalities on old proteins and probably most importantly new tissue specific regulation of genes arises by the addition of new promoters. Here is a recently observed example of exactly thatBefore you go off on the well that’s just de-evolution of an ancestral type here is an example of a mobile element providing a new promoter to an existing gene and generating new tissue specific regulation in primates Now I realize it seems that I’ve got way off topic but I assure you it is not so. Your main argument against the evolution of birds is from personal incredulity, evolving something this different isn’t possible. Other people have eloquently argued that flying could start without the highly intricate systems we see in birds today and how once flying got its start there would be very strong pressure to get better at it and really dominate the new niche. What I’m trying to add is that wings, and lungs and hearts and brains aren’t mutating the genes are. And its becoming more and more clear that very small mutations; moving a splice site, down regulating expression of a gene by adding polyA sequence in an intron or the incorporation of a new promoter from a mobile element is enough to generate major morphological change.If birds had really been "engineered" surely the creator would start again. To borrow an analogy from Dawkins the first jet engines weren't developed by bashing around prop' driven plane's engines, or just lengthening bolts of panels or cobbling together different parts of the original engine to create new functions. But that is how we, and fugu and birds work.This message has been edited by biochem_geek, 07-16-2004 05:27 AM

What nonsense. Lots of birds are more flightless than chickens, because they had no predators that they could escape through flight. The chickens, evolving under protective situations, artificially selected for traits other than flights are perfectly OK with poor flight.You are as bad as desotobul on the delphi forums.

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It's another square/cube thing. Weight is proportional to volume which is a cubed figure, while the ability to fly is ultimately ralated to surface area of wings, which is a squared figure.

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Which would only be true if the ancient bird was directly proportional to the bird used for comparison.So not alone are you very ignorant of Evolution; rather simple physics concepts also escapes you. Should I conclude that you really don't know ANY science?

It's also true that while volume goes up, weight might not. There is a difference between density and weight.

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Aslan is not a Tame Lion

i wasn't even going to bother with that, because it gets debated so often. (and i'd be more willing to call it a dinosaur than a bird, since it lacks several important bird features)i thought you meant modern birds, and i was just stupid.

you have a picture of an ica stone on the top of your page. look for the thread on those here... they're known forgeries.you also have a link to the hava supai pictograph, which looks nothing like any dinosaur that ever lived, but vaguely like an 19th century mangling of an iguanodon skeleton. (all hadrosaurs are quadrapedal. to stand upright, they'd have to break about 4 vertbrae in the lower tail.)but this bring up an interesting point. from the bones you say that grabity must have been less. well, if this was the case, all other animals present at the time would be subject to same forces. humans would be a lot bigger on average if they lived at the same time.so pick one. either dinosaurs lived with humans, or gravity was less. one crackpot theory at a time.

Most of the literature I've read classifies it as bird and not dinosaur, but it's sufficiently transitional that there's no simple way to choose where to put it.That, of course, is the strongest argument for evolution, and also the strongest argument against Redwolf's position - either Archaeopteryx is a bird who lacks many of the features RW claims birds couldn't survive without, or it's a non-bird with many of the features RW claimed would be survival liabilities in a non-bird.

exactly.

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you have a picture of an ica stone on the top of your page. look for the thread on those here... they're known forgeries.

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The ica stones are not forgeries. The original discovery involved several tens of thousands of the things; nobody ever did that much work on the off chance that gringos might be willing to buy all of them, i.e. on pure speculation. Carving one of those things would take weeks and God knows what it would take to carve one and then try to make it appear ancient as they all do.

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you also have a link to the hava supai pictograph, which looks nothing like any dinosaur that ever lived, but vaguely like an 19th century mangling of an iguanodon skeleton.

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To most people it looks like a sauropod dinosaur. The web site also links to other images of known dinosaur types, such as the sauropod dinosaur at the state park in Utah: edited to fix page width - The QueenThis message has been edited by AdminAsgara, 07-16-2004 11:17 AM

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So not alone are you very ignorant of Evolution; rather simple physics concepts also escapes you. Should I conclude that you really don't know ANY science?

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Don't act surprised when you find your comments being ignored...