Figure 1 in A review on deep molluscan phylogeny: old markers, integrative approaches, persistent problems

Figure 1. Major competing hypotheses on molluscan phylogeny and evolution. Left: Consensus tree from phylogenomics according to Telford and Budd (2011) and Kocot (2013), showing a basal split into Aculifera and Conchifera, and Monoplacophora sister to Cephalopoda; suggesting that worm-like body constructions of aplacophorans are secondary simplifications of a more complex ancestor (Scheltema 1993). Right: Morphocladistic tree from Haszprunar (2000), showing basal paraphyletic aplacophorans, monophyletic Testaria and Conchifera with basal Monoplacophora, implying progressive evolution from worm-molluscs to shell plate-bearing chitons and towards molluscs with true shell (Salvini-Plawen 2006). The taxon Serialia (Giribet et al. 2006) is incompatible with traditional Testaria, Aculifera and Conchifera concepts.