A synthesis maps colony form, life cycle and medusa characters onto published hydrozoan phylogenies; the inferred gains and losses are comparative reconstructions rather than directly observed ancestral states.
claim:taxon:hydrozoaCharacter evolution in Hydrozoa (phylum Cnidaria)
Cartwright, P.; Nawrocki, A.M.
Year2010
Source rolesystematic-review
DOI / ID10.1093/icb/icq089
Fitness and scope
taxonomy · topology · morphology
Review mapping hydrozoan life-cycle characters onto published phylogenies; reconstructed transitions are not direct observations of ancestors.
Claim ledger
Hydrozoa has no supported scalar temporal range in the cited evidence: the character-evolution review does not document a diagnostic 520 Ma hydrozoan fossil or crown boundary, so the former 520–0 Ma display is withheld.
claim:taxon:hydrozoa:range-boundary-rc50