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
Branching order of bacterial phyla (Cavalier-Smith, 2002) Branching order of bacterial phyla (Cavalier-Smith, 2002) There are several models of the Branching order of bacterial phyla, one of these was proposed in 2002 and 2004 by Thomas Cavalier-Smith. In this frame of work, the branching order of the major lineage of bacteria are determined based on some morphological characters, such as cell wall structure, and not based on the molecular evidence (molecular phylogeny). Whereas modern molecular studies point towards the root of the tree of life being between a monophyletic Bacteria and Archaea+Eukarya (Neomura), in the Cavalier-Smith theory, the last common ancestor (cenansestor) was a Gram-negative diderm bacterium