THE LOWER CAMBRIAN FOSSIL ANABARITIDS: AFFINITIES, OCCURRENCES AND SYSTEMATICS

Anabaritics, or angustiochreids, are extinct organisms with mineralised tubular and mostly triradially symmetrical exoskeletons known from Lower Cambrian beds worldwide. They are particularly abundant and diverse on the Siberian Platform, from where their first representatives have been formally described. About 70% of the published species names and all valid genera are known from Siberia, which makes this region particularly important for revision of the group. A few species of anabaritids are also reported from such crustal units as Western Mongolia, Kazakhstan, South and North China, Eastern and Western Gondwana, Avalonia, Laurentia and Baltica. This study is mainly based on the extensive collections available from the Siberian Platform, including material illustrated in publications, and it provides a systematic review of the diversity of the group. The evaluation of taxonomically important features by different authors is assessed in order to find a balance between taxonomic oversplitting of anabaritids, which has resulted in 72 species being named to date, and unsubstantiated lumping. Of the 19 published genera we place 14 in synonymy, on the basis of our analysis of the type material. The genera Anbarites, Combrotubulus, Selindeochreo, Aculeochrea and Mariochrea may be retained. We are inclined to regard anabaritids as diploblastic-grade metazoans similar to, or located within, the Cnidaria. There is, however, no firm evidence for that and they are, therefore, collectively referred to herein as a group incertae sedis.