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Figure 17 | EvoDevo

Figure 17

From: Embryonic neurogenesis in Pseudopallene sp. (Arthropoda, Pycnogonida) includes two subsequent phases with similarities to different arthropod groups

Figure 17

Two scenarios on the evolution of arthropod neurogenesis. Both scenarios are set against the backbone of the Chelicerata (Pycnogonida + Euchelicerata) and the Mandibulata (Myriapoda + Tetraconata) hypotheses. Onychophora are taken as the out-group but do not help significantly in the establishment of the arthropod stem species pattern. Colour code of characteristic features: green = apomorphic, red = plesiomorphic, black = apomorphic vs. plesiomorphic unclear, grey = in need of verification. Grey box at the bottom shows the reconstructed features in the arthropod stem lineage. (A) Convergent evolution of pycnogonid NSCs and tetraconate NBs. (B) Common origin of pycnogonid NSCs and tetraconate NBs from an ancestral NSC type with subsequent lineage-specific evolution of the latter. The critical assumption in this scenario is the occurrence of NSCs in myriapods.

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ISSN: 2041-9139