File:T.Cavalier-Smith (2017) Rstb20150476f01 - CC(BY)4.0.jpg

English: Figure 1. Cell structure divergence in phagotrophic non-amoeboid flagellates provided the basis for evolving animals, fungi, plants and chromists. Pseudopodia evolved secondarily, myosin II providing the basis for pseudopodia in animals, Amoebozoa (and Percolozoa) and muscles. Chloroplasts, originating when the plant ancestor enslaved and modified undigested cyanobacteria, were transferred laterally (red arrow) to make chromists (e.g. brown seaweeds, diatoms, dinoflagellates) whose ancestor modified an enslaved undigested red alga. The most basic eukaryote structural dichotomy contrasts Euglenozoa (parallel centrioles; cilia with paraxonemal rods; cytopharynx for feeding) and excavates (Percolozoa, Eolouka, Neolouka: orthogonal centrioles: no paraxonemal rods; feeding by phagocytosing prey drawn into a ventral groove by posterior ciliary currents). The pre-animal lineage lost excavate groove-feeding by evolving ventral ciliary gliding locomotion to generate Sulcozoa, protozoa with a dorsal proteinaceous pellicle (blue). Irrespective of whether the eukaryote tree is rooted within the protozoan subkingdom Eozoa as shown (most likely) or beside Eolouka-like Reclinomonas with the most primitive mitochondria, the immediate ancestors of animals (Choanozoa) arose by loss of the anterior cilium and sulcozoan dorsal pellicle to make opisthokonts (in red) with a radically simplified, more radially symmetric, microtubular cytoskeleton. Long actin-supported filodigits arose in the ancestor of Filosporidia and choanoflagellates and became a circlet of microvilli to make the choanoflagellate/sponge collar for catching bacteria. Filosporidia comprise Filasterea, Ichthyosporea, Corallochytrea [12]. The four derived kingdoms (e.g. ANIMALIA, PLANTAE) are shown in upper case; all taxa in lower case belong to the basal eukaryotic kingdom Protozoa.