The process whose specific outcome is the progression of the ammon gyrus over time, from its formation to the mature structure. The ammon gyrus, often subdivided into the CA1 and CA3 regions, is one of the two interlocking gyri of the hippocampus that is rich in large pyramidal neurons. [ http://openisbn.com/search.php?q=0838580343&isbn=1/ http://purl.obolibrary.org/obo/go/references/0000021 GOC:cls GOC:jid GOC:dph GOC:dgh ]