[dragonwriter]

> it seems at least mildly surprising that we've never observed at least similarly structured creatures.

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, since them arising in a species in which they are survival-useful is a matter of chance, as is their preservation.

So, its not surprising that features we haven't seen in other species is continue to be discovered. Its remarkable enough to be newsworthy and interesting, but not something that fundamentally challenges the expectations and understandings we have from basic understanding of evolution.

[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.