The functional and evolutionary significance of blastoid hydrospires

The supported blastoid record used here extends from the Sandbian Macurdablastus uniplicatus to a Wuchiapingian last occurrence near 255 Ma; a Permian–Triassic boundary endpoint would be an extinction inference rather than the observed last appearance.

The displayed blastoid evidence is restricted to named Sandbian and Wuchiapingian records in its source studies and does not establish a global distribution, origin centre or extinction geography.

The cited systematic and hydrospire studies do not establish a class-wide diet, habitat preference, locomotor performance, body-size distribution or guild for Blastoidea; these fields remain unresolved.

Macurdablastus is a named blastoid with source-described morphology, and hydrospire interpretation is retained as a source-bounded functional-morphology result rather than a class-wide invariant trait.