A 17‐element conodont apparatus from the Soom Shale Lagerstätte (Upper Ordovician), South Africa

Natural assemblages of a new conodont taxon, Notiodella keblon, from the Upper Ordovician Soom Shale Lagerstatte of South Africa contain 17 elements. This is the first time that a 17-element apparatus plan has been unequivocally demonstrated in conodonts. The apparatus comprises paired P1 ,P 2 ,P 3 ,M , S 1 ,S 2 ,S 3 and S4 ele- ments and an unpaired, axial S0 element and provides a new template for use in the reconstruction of apparatuses from the collections of dispersed elements, particularly for those with icrion-bearing P1 elements and perhaps for other balognathids. The fossil record of conodonts is almost entirely made up of scattered tooth-like skeletal elements that became dispersed in the sediment following the death and decom- position of the animals, or following their ingestion by other organisms. Very occasionally, partial or complete skeletal apparatuses are preserved as fused clusters of ele- ments or as natural assemblages on bedding planes and these provide valuable direct evidence for the composition and architecture of the conodont skeleton. However, only a few localities in the world have produced natural assem- blages or clusters, and only a few conodont genera are rep- resented by completely preserved skeletal apparatuses. For this reason, discoveries of natural assemblages representing additional taxa continue to be of fundamental importance for conodont palaeontology. The assemblages provide the only direct evidence of the number of elements in the skel- eton, and for the orientation and topological position of each element; known assemblages also furnish templates for the reconstruction of the apparatuses of other taxa that are known only from scattered elements. The framework provided by known apparatuses forms the basis of our interpretation of element homologies throughout the conodont clade (Donoghue et al. 2008). To date, described natural assemblages of conodonts with multidenticulate and ⁄ or platform elements fall into two main groups. Apparatuses of 15 elements are the most widely represented and comprise the first group; these con- sist of two pairs of P elements, one pair of M elements and