First cladistic analysis of the trilobite family Olenidae from the Furongian and Ordovician

VIVIANA A. CONFALONIERI; DANIELA S. MONTI

LETHAIA

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2019 vol. 52 p. 304 - 322

0024-1164

The Olenidae stands out for its abundance and biostratigraphical importance, especiallyin the Lower Palaeozoic rocks of northwestern Argentina. Their phylogeneticrelationships have been traditionally determined stratigraphically and by direct morphologicalcomparison. This study reports the first formal phylogenetic analysis of olenids.Eighty‐six characters (24 quantitative and 62 qualitative) were coded for 65 taxa(58 olenids). Quantitative characters were treated both as discrete and as continuousvariables. To explore the best way of character coding for this group, continuous characterswere coded as: median, log‐median, normalized and rescaled. Maximum parsimonyand implied weighting were used as optimality criteria. A phylogenetichypothesis more consistent with traditional taxonomy was reconstructed with bothquantitative and qualitative partitions. All the trees obtained with quantitative characterscoded as continuous and rescaled are better resolved, and those topologies weremore similar among them. This treatment also reflects more effectively the behaviourof the original variables. Olenidae is not a monophyletic clade: Andrarina costata andAphelaspis australis are included within the ingroup, as sister clade of Olenus gibbosus.Also, the results suggest that members of the Hypermecaspidinae constitute a newfamily within the Order Olenida. The traditional taxonomic scheme at subfamily levelis partially supported. Triarthrinae and ?pelturinds? are recovered as monophyleticclades, but Oleninae is polyphyletic. This study proves, through a formal cladistic analysis,that characters disregarded by traditional taxonomy can be uncovered. Finally,this is the first step towards achieving a classification of the Olenidae taking intoaccount the evolutionary process involved in its diversification history.