[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: The Future is Wild



David Marjanovic wrote-

> You won't like it that much. Looks like the authors
> assume quite some directionality in evolution and aren't too keen on
design
> constraints. Terrestrial vertebrates die out, what happens? Squid evolve
> internal skeletons and walk the earth.

I don't see what your problem with this is.  Assuming terrestrial
vertebrates went extinct (and what an extinction that would be), something
would recolonize land.  It's not that evolution shows a direction towards
terrestriality, it's just that environments tend to become filled unless
they are extremely hazardous (eg. no atmosphere in space, very high
temperatures deep enough underground).  Though I could picture annelids,
arthropods or any number of other invertebrate phyla becoming the main clade
of large terrestrial animals, cephalopods do seem well equipped for the job
(octopuses already have cartilaginous braincases after all).  Sure, you
could have fish turn terrestrial again (through mudskippers, lungfish, or
what have you), but I would think the resulting "paratetrapods" would
suggest more directionality than these cephalopods do.  As for design
constraints, who could have guessed Pikaia would be the ancestor of reptiles
200 million years after it existed?  Compared to the changes involved there,
squibbons and megasquid are too conservative if anything.

Mickey Mortimer