Which 2 mollusks were found on the floor of the ocean during the Mesozoic era? What is the significance of each?
a) Ammonites and Belemnites; Ammonites were important index fossils and Belemnites were predators
b) Nautiloids and Trilobites; Nautiloids were ancestors of modern cephalopods and Trilobites were extinct arthropods
c) Gastropods and Bivalves; Gastropods were abundant snails and Bivalves were filter-feeding clams
d) Cephalopods and Crinoids; Cephalopods were squid-like creatures and Crinoids were marine animals resembling plants