section_path: Evolutionary history/Evolution and classification of living arthropods
section_name: Evolution and classification of living arthropods
paragraph_text: Evolution and classification of living arthropods
  
  The phylum Arthropoda is typically subdivided into four subphyla, of which one is extinct:
  
  The phylogeny of the major extant arthropod groups has been an area of considerable interest and dispute. Recent studies strongly suggest that Crustacea, as traditionally defined, is paraphyletic, with Hexapoda having evolved from within it, so that Crustacea and Hexapoda form a clade, Pancrustacea. The position of Myriapoda, Chelicerata and Pancrustacea remains unclear as of April 2012. In some studies, Myriapoda is grouped with Chelicerata (forming Myriochelata); in other studies, Myriapoda is grouped with Pancrustacea (forming Mandibulata), or Myriapoda may be sister to Chelicerata plus Pancrustacea.
  
  The following cladogram shows the internal relationships between all the living classes of arthropods as of the late 2010s, as well as the estimated timing for some of the clades: