A reassessed character matrix tests whether trilobites require a long cryptic history before their abrupt fossil appearance.
Represented range521.5–518 Ma
RegionsGlobal lower Cambrian occurrence and morphology sample
CladesTrilobita · Artiopoda
Claim ledger
topology · medium
A reassessed early-arthropod morphology matrix supports a relatively short cryptic interval before the approximately 521 Ma appearance of widespread trilobites; topology and origin time are analytical outputs rather than a Precambrian absence test or a direct fossil date.