when did cephalopods first appear
Cephalopods include squid, octopus, cuttlefish, nautilus, spirula, and the extinct ammonites and belemnites. Cephalopods first appear in the fossil record nearly 500 million ago during the Ordovician Period. They are all mollusks, members of the same Phylum Mollusca as oysters, conches, and the common garden snail.