[Taxacom] Tardigrades ----> to Nematodes

[Kenneth Kinman]

Dear All,
     There is increasing evidence that tardigrades and nematodes are
closely related to one another.  So the temptation will be to view
tardigrades as having evolved from nematodes by developing legs, etc.      
      I think this is backwards.  It is probably more likely that a
primitive tardigrade began to lose it legs because they became
increasingly useless in certain habitats (much like snakes evolving from
a lizard).  Therefore, I am not at all surprised that there have been no
nematode fossils found in the Cambrian, because in my opinion, nematodes
probably had simply not evolved yet.  If they can find fossils of
microscopic animal embryos in the Cambrian of China, then they should
have found nematodes as well (if they did exist in the Cambrian).  
          --------Ken Kinman