Carbonaceous nervous tissues test whether neuroanatomical and appendicular signals tell the same stem-chelicerate history.
Represented range508.1–505 Ma
RegionsBurgess Shale, British Columbia, Canada
CladesMollisonia symmetrica · Chelicerata
Claim ledger
topology · contested
Carbonaceous films in Mollisonia symmetrica specimens MCZ 1811 and USNM 305093 preserve optic nerves, a possible compact cephalic synganglion and a segmental ventral nerve cord; incomplete preservation and conflicting appendicular signal make ancestral organization and stem placement contested.