Conodonts are an enigmatic group of spikey toothlike microfossils that occur in marine rocks that range in age from Cambrian to Triassic. Their phylogenetic affinity has been the subject of debate for over a century, largely because the only clue to their affinity were the microscopic teeth, which show vague similarities to structures in a broad range of organisms. With the discovery of remains of the otherwise entirely soft-bodied organism, conodont palaeobiology has experienced something of a renaissance. Conodonts are now widely regarded to be primitive vertebrates or invertebrate chordates, possibly providing the earliest evidence of skeletonization within vertebrate phylogeny.

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Left to right: a range of conodont elements mounted on a pin head for scale (Purnell et al 1995), a thin section through an element of Cordylodus (Donoghue 1998), and a model of the feeding apparatus of Idiognathodus (Purnell and Donoghue 1997).

Phil has been integrally involved in recent efforts to uncover the evolutionary relationships of conodonts and of the intrarelationships of the group, as well as functional morphology, histology and growth of the conodont skeleton. Current research is focussed on the evolutionary relationships of paraconodonts and euconodonts, as well as the development of a phylogenetically-based scheme of systematics for the group.