Is Haootia quadriformis related to extant Staurozoa (Cnidaria)? Evidence from the muscular system reconsidered

Haootia preserves repeated aligned impressions in a tetraradial body, interpreted as muscle bundles and compared with Staurozoa, but fibre identity and detailed homology have competing primary assessments.

Haootia preserves repeated aligned impressions in one Ediacaran holotype, but muscle identity, orientation and staurozoan comparison have competing primary interpretations; the specimen does not set a Staurozoa or Cnidaria range.

Haootia is displayed at approximately 560 Ma only as the age estimate for its type material used by competing muscular-cnidarian interpretations; it is not a crown-Staurozoa FAD, direct ancestor or global genus duration.

Staurozoa has no supported scalar crown range in the cited evidence: extant systematics does not date the crown and the Haootia comparison is contested, so the former 562–0 Ma display is withheld.

Haootia quadriformis is retained as an Ediacaran cnidarian candidate because the holotype was described in a muscular-cnidarian framework, while later primary studies dispute the staurozoan comparison and keep its precise placement open.

The Haootia holotype preserves a roughly quadrate body impression with repeated aligned internal structures; muscle identity and their orientation remain competing interpretations rather than observed histology.