After Parker, 1982 and Szaniawski, 2002, 2005
<==o Chaetognatha [incl. †Protoconodonta] (arrow worms; nuolimadot) |?- †Eognathacantha ercainella Chen & Huang, 2002 [assigment doubtful] |--o †Protoconodonta [paraphyletic assemblage of basal chaetognaths?] | |-- †Coelocerodontus Ethington, 1959 | |-- †Protohertzina Missarzhevsky, 1973 | `--o †Phakelodus | |-- †P. tenuis (Müller, 1959) | `-- †P. elongatus (Zhang, in An et al., 1983) `--o Chaetognatha sensu stricto (nuolimadot) |?- †Titerina rokycanensis Kraft & Mergl, 1989 [very dubious] |?- †Paucijaculum samamithion Schram, 1973 |-- †Onesia disjuncta Walcott, 1911 `--o Sagittoidea |?- Archeterokrohnia rubra Casanova, 1986 [Heterokrohniidae] |?-o Heterokrohnia Ritter-Záhony, 1911 | |-- H. longidentata Hagen & Kapp, 1985 | `-- H. longicaudata Hagen & Kapp, 1986 |?-o Paraspadella Salvini Plawen, 1987 | |-- P. getoi | `-- P. schizoptera (Conant, 1895) |?- Serratosagitta Tokioka, 1965 |?- Flaccisagitta Tokioka, 1965 |?- Parasagitta Tokioka, 1965 |?- Tokiokaispadella Kassatkina, 1980 |--o Phragmophora | |--o Spadellidae | | `--o Spadella Langerhans, 1880 | | `-- S. gaetanoi Alvariño, 1978 | `--o Eukrohniidae | `-- Eukrohnia Ritter-Záhony, 1909 `--o Aphragmophora |--o Ctenodontina | |--o Sagittidae | | `-- Sagitta Quoy & Gaimard, 1827 | `-- Pterosagittidae `--o Flabellodontina `-- Krohnittidae
Reference(s):
- Parker, S. P. (ed.), 1982: Synopsis and classification of living organisms. Vols. 1 & 2
–McGrew-Hill Book Company - Szaniawski, H., 2002: New evidence for the protoconodont origin of chaetognaths.
–Acta Palaeontologica Polonica: Vol. 47, #3, pp. 405-419 - Szaniawski, H., 2005: Cambrian chaetognaths recognized in Burgess Shale fossils.
–Acta Palaeontologica Polonica: Vol. 50, #1, pp. 1-8