Crown-group asteroid phylogeny: An enduring quandary

The phylogeny of crown-group asteroids has been problematic since the Mortensen-MacBride debate of the 1920s in spite of the availability of many lines of evidence. Understanding has not been clarified by recent molecular approaches. The fossil record is too scanty to provide more than timing, ideas on trends, and infrequent "jackpot" fossils. Development and comparative anatomy of soft parts has been neglected in recent years. Skeletal data, especially that of the ambulacral column, continues to be promising. Ossicular variation at all levels must be addressed, probably using computer-imaging techniques accompanied by statistical analyses, as has been done for other phyla. Work to date has focused on family-level exemplars; treatment of all available genera within families and species within genera is needed.