title: The evolutionary origin of the vertebrate body plan: the problem of head segmentation.
abstract: The basic body plan of vertebrates, as typified by the complex head structure, evolved from the last common ancestor approximately 530 Mya. In this review, we present a brief overview of historical discussions to disentangle the various concepts and arguments regarding the evolutionary development of the vertebrate body plan. We then explain the historical transition of the arguments about the vertebrate body plan from merely epistemological comparative morphology to comparative embryology as a scientific treatment on this topic. Finally, we review the current progress of molecular evidence regarding the basic vertebrate body plan, focusing on the link between the basic vertebrate body plan and the evolutionarily conserved developmental stages (phylotypic stages).
authors.affiliation: Laboratory for Evolutionary Morphology, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan; email: tonai@cdb.riken.jp , irie@biol.s.u-tokyo.ac.jp , saizo@cdb.riken.jp.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Onai
authors.forename: Naoki
authors.initials: N
authors.lastname: Irie
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kuratani
mesh_terms: D000818:Animals; D005075:Biological Evolution; D019521:Body Patterning / Q000235:genetics; D006257:Head / Q000033:anatomy & histology / Q000254:growth & development*; D008962:Models, Theoretical; D009024:Morphogenesis / Q000235:genetics*; D010802:Phylogeny; D014714:Vertebrates / Q000033:anatomy & histology / Q000254:growth & development*
keywords: head segmentation; hourglass model; recapitulation; vertebrate body plan