[Taxacom] Origin of arthropods

[Kenneth Kinman]

Dear All,      I've catching up on the past few years articles on the origin of arthropods.  I am very happy to see a consensus forming that Euarthropoda are descendants of a paraphyletic group of bivalved arthropods.  That is an extremely important advance.          However, almost all of the cladistic analyses (including Figure 4 in the paper below) continue to assume that these bivalved arthropods evolved from a paraphyletic series of lobopod taxa (tardigrades, onychophorans, Opabinia, and anomalocaridids).  I believe that exactly the opposite is true, and that lobopod taxa evolved from bivalved arthropods through the loss of their bivalves and then the loss of compound eyes and other losses.         If this proves true, the bivalved arthropods should be at the base of such trees, giving rise to increasingly complex forms (Euarthropoda) on the one hand, but also to increasingly "simplified" forms (lobopodans, etc.) on the other hand.  If you assume that lobopods are the outgroups and that assumption is false, it will tend to prevent further progress on determining the real outgroups of these bivalved arthropods (and thus the interrelationships of Arthropoda with other phyla).  Anyway, take a look at Figure 4 in the following paper:  
https://www.researchgate.net/publication/260912145_Frontiers_in_Palaeontology_Origins_and_early_evolution_of_arthropods
                               -----------------------Ken