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Comment by xerophtye | Hacker News Reader

As amazing as the article is, i have one confusion. What about dinosaurs?

In the eagle part, he said eagles CAN'T be as big as tigers etc. But what about Pterodactyls? How did they manage to be so big?

Oh and weren't all the dinosaurs cold-blooded? So, if I am not mistaken, didn't the author say that we get over the problem of heat loss by being warm-blooded? Or does that just mean that they had to eat ALOT more? (though i suppose due to frequent volcanic eruptions etc maybe the environment was hot enough to sustain them)

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Earth's atmosphere had more oxygen in it back then, which it easier to be big.

The size is not only determined by the underlying physics, but also by the environment. So there can be a arms race of size, the predator needs to be roughly the same size as its pray, so the larger pray has a evolutionary advantage which gives larger predators an evolutionary advantage.

And to stay with the analogy of the article, the same is true for organizations. Some parts of organizations need to be as large as the corresponding parts of competing organizations. For example the legal department and marketing.

I wouldn't say it doesn't depend on the physics. Of course it does. As for my original question, i realize the flying mechanism of an eagle is completely different from that of a Quetzalcoatlus (thank you @sejje). Modern day birds use their feathers to trap air (or somthing like that), no? Where as the Quetzalcoatlus would simply use the surface-area of their leathery wings to glide, like human-made gliders.

Check it out. Six years ago Yahoo! answers had some decent answers:

http://answers.yahoo.com/question/index?qid=20080301144511AA...

Dinosaurs were not cold blooded as it turns out. They live on today as birds.

We don't actually know that. And part of the reason is "dinosaurs" is such a broad term, encompassing so many species of many millions of years. I would think it's mostly likely that some dinosaurs were cold-blooded and some warm-blooded.

I have also attended a talk that suggested that some dinosaurs almost certainly didn't fit the warm-blooded or cold-blooded model, and that despite mechanically being cold-blooded, their large size alone kept them warm. So in many ways those ones were practically warm-blooded.

Pterodactyls were small. They had roughly the same wingspan as the modern bald eagle.

Maybe if bald eagles had 36-foot wingspans: http://en.wikipedia.org/wiki/Quetzalcoatlus

I wasn't intending to be nitpicking or pedantic when I wrote it - it was just something I remembered off the top of my head - but those aren't, strictly speaking, pterodactyls. I hadn't considered that the use was the generic term.

See:

http://en.wikipedia.org/wiki/Pterodactyloidea

http://en.wikipedia.org/wiki/Pterosauria

(Technically correct; the best kind of correct.)

woah! i didnt realize it was a FAMILY of dinosaurs and not just a particular one

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