Occasionally, the authority of the consuls was temporarily superseded by the appointment of a dictator, who held greater "imperium" than that of the consuls. By tradition, these dictators laid down their office upon the completion of the task for which they were nominated, or after a maximum period of six months, and did not continue in office longer than the year for which the nominating consul had been elected. However, in four years at the end of the fourth century BC, dictators are said to have continued in office in the year following their nomination, in place of consuls. Modern scholars are skeptical of these years, which might be due to later editing of the lists of magistrates in order to fill a gap. All known dictators have been included in this table.