Fig. 8 in A new Late Ordovician bubble-headed trilobite species from South West Wales and its implications for biostratigraphy

Fig. 8. Graph showing the number of lateral denticles on librigenae of various Staurocephalus species through time. Circle represents the mean, vertical lines the range where one was observed in that species. Chatterton and Campbell (1980) described S. struszi as having "twelve (possibly eleven on some specimens)" denticles. Species names in black font represent occurrences in England and Wales, those in red font occur outside Avalonia. Note that Cautleyan and Rawtheyan are regional stages from the AngloWelsh chronostratigraphy and belong in the upper part of the international Katian Stage. The remaining stages are international. The Telychian is approximately twice the length of the other stages (e.g., Ogg et al. 2008: fig. 1.1), hence the wider spacing allocated to it.