Jovan Hadži theories of animal evolution. He devised a system of classification in which he divided the animal kingdom into six phyla: Protozoa, Parazoa, "Ameria" (animals with no segments), "Oligomeria" (animals with few segments), "Polymeria" (animals with many segments) and Chordata. His choice of characters important for classification was generally discredited by his contemporaries, and the system was never accepted by zoologists. However, due to its simplicity, the system was widely used in science education in former Yugoslavia. His other major theory was that of the origin of metazoa - he developed an existing hypothesis stating that the first multicellular animals resembling
Bacterial phyla WYO, ZB3, and Zixibacteria). Despite the unclear branching order for most bacterial phyla, several groups of phyla have clear clustering and are referred to as superphyla. The FCB group (now called Sphingobacteria) includes Bacteroidetes, the unplaced genus "Caldithrix", Chlorobi, candidate phylum Cloacimonetes, Fibrobacteres, Gemmatimonadates, candidate phylum Ignavibacteriae, candidate phylum Latescibacteria, candidate phylum Marinimicrobia, and candidate phylum Zixibacteria. The PVC group (now called Planctobacteria) includes Chlamydiae, Lentisphaerae, candidate phylum Omnitrophica, Planctomycetes, candidate phylum Poribacteria, and Verrucomicrobia. The proposed superphylum, Patescibacteria, includes candidate phyla Gracilibacteria, Microgenomates, Parcubacteria, and Saccharibacteria and possibly Dependentiae. These same candidate phyla, along with candidate phyla Berkelbacteria, CPR2,