Redescription of Macurdablastus and redefinition of Eublastoidea as a clade of Blastoidea (Echinodermata)

Eublastoids are a large clade of blastoids; stemmed blastozoan echinoderms diagnosed by their conservative body plan (three basals, four deltoid plates and five radial plates), lancet plate supporting the ambulacra, and hydrospire respiratory structures. Although Eublastoidea was a highly successful clade in the middle and late Palaeozoic it is absent from early echinoderm radiations seen in the Cambrian and Ordovician record. Here we provide a...