THE CLASSIFICATION OF ATHYRIDID BRACHIOPODS

Phylogenetic relationships among higher taxa of articulate brachiopods that developed a spiralium as mineralized support for the lophophore, and the resulting classifications, are not universally agreed upon du e to the complex pattern of character evolution within the phylum. Our results, using phylogenetic methodology in conjunction with tradition al methods, showed a more complete and easily testable picture of this evolution than either method used alone. A detailed working hypothesi s of athyridide phylogeny and the supporting evidence on character dis tribution is given, and a new classification of the impunctate and pun ctate athyrids sensu late is presented with diagnoses to subfamily. Ag reement between the stratigraphical first appearance of athyridid subf amilies and their cladistic rank was quite good (except for the koninc kinoids), suggesting that both outgroup and traditional paleontologica l methods indicate a similar direction of character polarity in the ev olution of the group. The classification is proposed based on a mix of external and internal characters which persisted during unbroken line ages. New taxa are the families Parazygidae and Triathyrididae; the su bfamilies Whitfieldellinae, Triathyridinae, Septathyridinae, Cleiothyr idininae, Ochotathyridinae and Plectospirinae, and the genera Brimethy ris, Carteridina, Tetraloba and Cooperispira. We studied the gear morp hological diversity among the athyridids. Their complete stratigraphic al ranges help in building phyletic lineages.