The historical Acanthodii navigation grade begins at the approximately 439 Ma Fanjingshania dermoskeletal sample, which the cited analysis places on the chondrichthyan stem; the 252 Ma younger edge is a rounded legacy composite, not evidence that Acanthodii is monophyletic or that Fanjingshania is a direct ancestor or global first occurrence. This navigation entry is not a phylogeny or a complete taxon dossier.
Represented range439–252 Ma
Content packageearly-fishes
PBDBtxn:34849
Evidence boundary
Automated checks cover structure, identifiers, translations and links only; maintainer and external expert review are not complete.
Claim ledger
fossil-range · medium
The historical Acanthodii navigation grade begins at the approximately 439 Ma Fanjingshania dermoskeletal sample, which the cited analysis places on the chondrichthyan stem; the 252 Ma younger edge is a rounded legacy composite, not evidence that Acanthodii is monophyletic or that Fanjingshania is a direct ancestor or global first occurrence.
claim:taxon:acanthodii:fossil-range
Known limits
A missing branch or fossil occurrence does not imply biological absence. Internal nodes are not calibrated divergence estimates.