File:Rsos211134f01.jpg

English: Figure 1. Proposed segmental affinities of stem-group euarthropod appendages and resulting hypotheses of stem euarthropod relationships. (a) Radiodont frontal appendages protocerebral, megacheiran great appendages deutocerebral, fuxianhuiid specialized post-antennal appendages tritocerebral (e.g. [7]). Deuteropods including paraphyletic bivalved euarthropods such as Jugatacaris and fuxianhuiids occupy position immediately crownwards of radiodonts (morphological matrix of e.g. [3,16]). (b) Radiodont frontal appendages protocerebral, megacheirans and Kylinxia great appendages deutocerebral [9]. Kylinxia occupies position immediately crownwards of radiodonts (morphological matrix of [9]). (c) Radiodont frontal appendages and megacheiran great appendages both deutocerebral [17]. Megacheirans occupy position immediately crownwards of radiodonts (morphological matrix of e.g. [17]). (d) Radiodont frontal appendages, megacheiran great appendages and fuxianhuiid specialized post-antennal appendages all protocerebral [18]. Megacheirans occupy position immediately crownwards of radiodonts (phylogenetic support untested). Black dot marks the base of Deuteropoda in all trees. Radiodont frontal appendage (Houcaris saron) redrawn from [19]: figure 1; Jugatacaris redrawn from [20]: figure 14; fuxianhuiid appendage (Alacaris) redrawn from [16]; Kylinxia great appendage redrawn from [9]: figure 3B; megacheiran great appendage (adult Yohoia tenuis) redrawn from [21]: figure 10D. Abbreviations: ant, antennae; ba, biramous appendage; De, Deuteropoda; fa, frontal appendage; ga, great appendage; hyp, hypostome/labrum complex; spa, specialized post-antennal appendage.