title: Definitions in phylogenetic taxonomy: critique and rationale.
abstract: A general rationale for the formulation and placement of taxonomic definitions in phylogenetic taxonomy is proposed, and commonly used terms such as "crown taxon" or "node-based definition" are more precisely defined. In the formulation of phylogenetic definitions, nested reference taxa stabilize taxonomic content. A definitional configuration termed a node-stem triplet also stabilizes the relationship between the trio of taxa at a branchpoint, in the face of local change in phylogenetic relationships or addition/deletion of taxa. Crown-total taxonomies use survivorship as a criterion for placement of node-stem triplets within a taxonomic hierarchy. Diversity, morphology, and tradition also constitute heuristic criteria for placement of node-stem triplets.
authors.affiliation: Department of Organismal Biology and Anatomy, University of Chicago, 1027 E. 57th Street, Chicago, Illinois 60637, USA. dinosaur@uchicago.edu
authors.forename: P C
authors.initials: PC
authors.lastname: Sereno
mesh_terms: D000818:Animals; D001717:Birds / Q000145:classification; D002965:Classification / Q000379:methods*; D008957:Models, Genetic; D015233:Models, Statistical; D010802:Phylogeny; D015203:Reproducibility of Results; D009626:Terminology as Topic