THE LATE PRECAMBRIAN FOSSIL KIMBERELLA IS A MOLLUSK-LIKE BILATERIAN ORGANISM

The fossil Kimberella quadrata was originally described from late Prec ambrian rocks of southern Australia(1), Reconstructed as a jellyfish(2 ), it was later assigned to the cubozoans ('box jellies'), and has bee n cited as a clear instance of an extant animal lineage present before the Cambrian(3-7). Until recently, Kimberella was known only from Aus tralia, with the exception of some questionable north Indian specimens (8), We now have over thirty-five specimens of this fossil from the Wi nter Coast of the White Sea in northern Russia, Our study of the new m aterial does not support a cnidarian affinity, We reconstruct Kimberel la as a bilaterally symmetrical, benthic animal with a non-mineralized , univalved shell, resembling a mollusc in many respects. This is impo rtant evidence for the existence of large triploblastic metazoans in t he Precambrian and indicates that the origin of the higher groups of p rotostomes lies well back in the Precambrian.