 These surnames were initially characteristic of patrician families, but over time cognomina were also acquired by the plebeians.However, a number of distinguished plebeian gentes, such as the Antonii and the Marii, were never divided into different branches, and in these families cognomina were the exception rather than the rule.Cognomina are known from the beginning of the Republic, but were long regarded as informal names, and omitted from most official records before the second century BC.