Heterochronic changes and ancestral developmental sequences for major malacostracan nodes. Simplified phylogram of Malacostraca with ancestral developmental sequences from the PGi superconsensus tree. Sequences are shown as columns of downward pointing arrows. Each arrow represents a different semaphoront containing a single event or a group of simultaneous events (abbreviations listed in Table 1). The position of Leptostraca is indicated by a dotted line. Ancestral ontogenetic sequences of the branchiopod/malacostracan, the eumalacostracan, the caridoid, and the decapod LCA are shown. Events are color-coded corresponding to Figures 3 and 10a. Heterochronic changes are indicated by horizontal arrows that use the same color code as the respective events. The egg nauplius phase is indicated by brackets. A symbolic nauplius drawing marks the terminal taxa, which develop nauplius larvae. Arrows with a ‘plus sign’ mark events that are interpreted as new evolutionary acquisitions on the respective branch. Arrows with a ‘minus sign’ indicate evolutionary loss of a feature. Abbreviations: ENP
egg nauplius phase. Event abbreviations are listed in Table 1.