Re: Transitional fish

>
> So where does the Darwin Fish fit in all of this? Sorry I couldn't resist
> :)
>
The Darwin Fish is rather like Piltdown Man-mixing elements from different
organisms. In particular, the homocercal tail is characteristic of actively
swimming actinopterygian fish, not of sarcopterygians.

> > Showing some ignorance here probably, but why is this so dramatically
> > different than the mudskippers that live today?
>
Mudskippers are to some extent reinventing the fish-tetrapod transition.
They have two major disadvanatages, however. One is the actinopterygian fin
structure, which is not nearly as suitable for modification into a sturdy
limb than the sarcopterygian lobe fin. Secondly, the tetrapods have over a
300 million year head start. Unless the mudskippers manage to find an
island that lasts for many millions of years without any terrestrial
tetrapods finding it, they're very likely to be outcompeted.

>(I believe "tetrapod" is too general a term, as tardigrades are tetrapods,
are they not, yet hardly derived from fish.)<

No, they're octopods, but tardigrades are not cephalopods, just as squids
and most of the familiar crustaceans are both decapods.

>Are you saying that Greenlander Ichthyostega and Acanthostega, and Latvian
Panderichthys MIGRATED!?<
Greenland is not that far from the the Canadian Arctic, where the new form
was found. In the late Devonian, most of modern Europe and most of modern
North America were a single continent, so the distance between Greenland,
northern Canada, and Latvia was neither as fas as it is today nor broken by
ocean (which would probably be an impassible barrier for these freshwater
animals). Also, note the dates-the organisms have at least a few million
years, if not tens of millions of years, to get from one place to another.
Land animals have had only about 3 million years to have continuous land
connection between North and South America, yet opossums, ground sloths, and
glyptodonts reached most of North America and North American forms such as
cats and dogs reached southern South America.

> --
> Dr. David Campbell
> 425 Scientific Collections
> University of Alabama
> "I think of my happy condition, surrounded by acres of clams"
>
Received on Wed Apr 12 15:12:39 2006