which members of the original taxon that we were talking about are consumed by humans?
Crabs, lobsters, shrimp, crawfish, and prawns.
Crustacean
Many crustaceans are consumed by humans, and nearly 10,700,000 tons were produced in 2007; the vast majority of this output is of decapod crustaceans: crabs, lobsters, shrimp, crawfish, and prawns. 
crustacea and hexapoda have what features in common It is now well accepted that the crustacean group is paraphyletic, and comprises all animals in the clade Pancrustacea other than hexapods. what is the first group that you are talking about? It forms a large, diverse arthropod taxon which includes such animals as crabs, lobsters, crayfish, shrimps, prawns, krill, woodlice, and barnacles. can you describe their body? It is composed of segments, which are grouped into three regions: the "cephalon" or head, the "pereon" or thorax, and the "pleon" or abdomen. and where do they generally live? Majority live in either marine or freshwater environments. have their fossils been found? Yes, they have a rich and extensive fossil record. can you name any organism of this taxon whose fossil has been discovered? Yes, "Canadaspis" and "Perspicaris". how is the former classified? It is currently thought to be a member of the group Hymenocarina.
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Crustacean [SEP] Consumption by humans
Many crustaceans are consumed by humans, and nearly 10,700,000 tons were produced in 2007; the vast majority of this output is of decapod crustaceans: crabs, lobsters, shrimp, crawfish, and prawns. Over 60% by weight of all crustaceans caught for consumption are shrimp and prawns, and nearly 80% is produced in Asia, with China alone producing nearly half the world's total. Non-decapod crustaceans are not widely consumed, with only 118,000 tons of krill being caught, despite krill having one of the greatest biomasses on the planet.