Metazoan diversification characterized by elevated rates of evolution during the middle Ediacaran to earliest Cambrian.

Molecular and phenotypic evolutionary rates rise through the Ediacaran, peaking in an Ediacaran and earliest Cambrian interval within Opisthokonta before declining afterward.

• Why it matters: The work addresses when and how animal body-plan diversification accelerated, testing hypotheses about developmental evolution and linking evolutionary tempo to major ecological transitions.
• What they did: Rates of molecular and phenotypic evolution were analyzed across the Tonian–Ordovician interval, with phenotypic characters partitioned into development, feeding, fossilization potential, locomotion, and nervous systems.
• The result: Developmental traits in the metazoan stem lineage contribute disproportionately to elevated phenotypic rates, and rate peaks show a temporal lag relative to ecological “revolutions,” largely independent of timescale.

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