The Family Olenidae (Trilobita, Arthropoda): A synopsis of its taxonomic composition, stratigraphic and paleogeographic distribution

This paper provides a list of all named species in the family Olenidae, along with their geographic and stratigraphic records. It also discusses each of the valid genera in the family and describes the composition of the entire group and its subfamilies in terms of species and generic richness across different periods and geographical areas. The family encompasses 64 genera and 394 species, primarily concentrated in the subfamilies Oleninae and Pelturinae (65.63% of the genera and 58.12% of the species). The Olenidae was first documented during the Guzhangian in Baltica, and subsequently, its range expanded globally to Eastern Gondwana (Australia), South China, and Siberia. The Furongian saw a peak in species diversity (61.88% of the total) and widespread distribution. During the Tremadocian, the number of species declined, yet the geographic range persisted, and this decrease continued for the rest of the Ordovician. Although the family is cosmopolitan, Baltica and Avalonia host almost half of the records (46.71%). Challenges in olenid systematics include species lacking proper illustrations and/or lost type materials, poorly diagnosed genera, and potential polyphyletic larger families. The study emphasizes the importance of precise species and genus delimitation. The dataset presented serves as an initial step in achieving a clearer phylogenetic classification of the family Olenidae.