Ostracodermi is retained only as a historical navigation grade spanning several jawless stem-gnathostome lineages, so the former 485–359 Ma composite is withheld rather than treated as a clade range.
claim:taxon:ostracodermi:range-boundaryEarly jawless vertebrates and cyclostome origins
Janvier, P.
Year2008
Source rolesystematic-review
DOI / ID10.2108/zsj.25.1045
Fitness and scope
taxonomy · topology · range
Review distinguishes the 358 Ma undoubted lamprey record, probable Late Carboniferous hagfish record and older molecular divergence; it does not identify a direct cyclostome ancestor or exact crown origin.
Claim ledger
Undoubted lampreys are reviewed from about 358 Ma and cyclostomes survive as living lamprey and hagfish lineages, supporting a 358 Ma–present evidence-route window rather than a precise crown origin.
claim:taxon:cyclostomata:range-boundaryThe reviewed record places undoubted fossil lampreys at about 358 Ma and living lampreys at the present, supporting a bounded 358 Ma–present evidence route but not a global order FAD.
claim:taxon:petromyzontida:range-boundary