Conodonts & their presumed relatives come known from either a Cambrian to the Late Triassic. A earliest forms come identified when protoconodonts, followed by paraconodonts, followed by euconodonts (or even "true conodonts").

Charted a discovery of eleven person fossils inside Scotland and South Africa, most paleontologists think conodonts — which turn out to own fins by owning fin rays, chevron molded muscles, the stiffening chord that is the precursor of the backbone, & eyes — come in the phylum Chordata. There are a great deal of opinions just about in which a conodonts belong amongst a chordates/vertebrates. Virtually all palaeontologist (charted Szaniawski) place a protoconodonts within a phylum along using the chaetognath worms, indicating that they are non close relatives of the avowedly conodonts. Complete fossils come uncommon, however a eleven imprints that stand been witnessed indicate an eel-rather animal sustaining Fifteen or even, further seldom, Xix elements forming the bilaterally symmetric array upstairs, comprising a feeding apparatus radically different from either the jaws of modern animate being.

Cladistic analyses by Donoghue et. al (1998, 2000) indicate that conodonts come craniate. A paraconodonts (known exclusively from either dentition) come thought to become related, however a relationship is unreadable. Based on data from Donoghue, protoconodonts are non related the rest.