[jlgreco]

"Its not surprising that some survival-valuable features (especially when they fulfill a function for which there are other mechanisms) arise and are preserved and further developed only once"

Indeed. In fact, what I find more surprising is that some non-trivial adaptations have developed more than once. Flight for instance evolved four separate times (bugs, birds, bats, and now-extinct pterosaurs all fly[flew], but none of them share a common ancestor that could also fly.) I find that simply remarkable. Really drives home the massive timescales that are involved.

[dragonwriter]

> Flight for instance evolved four separate times (bugs, birds, bats, and non-extinct pterosaurs all fly[flew], but none of them share a common ancestor that could also fly.)

Surely, "now-extinct pterosaurs", not "non-extinct pterosaurs", unless I missed some very newsworthy discovery.

[jlgreco]

Whoops, thanks for the correction.