^As
adoption was widely practiced by the upper classes, some Roman monarchs were not directly biologically related to their predecessors despite belonging to the same dynasty. For example, the second emperor of the
Julio–Claudian dynasty,
Tiberius, was in fact an adopted son of the dynastic founder,
Augustus.
^The rule of the
Severan dynasty was interrupted between 217 CE and 218 CE.
Caracalla was the last ruler before the interregnum.
Elagabalus was the first ruler after the interregnum.
^The rule of the
Heraclian dynasty was interrupted between 695 CE and 705 CE.
Justinian II was both the last ruler before the interregnum and the first ruler after the interregnum.
^In the aftermath of the
Fourth Crusade, the
Laskarid dynasty of the
empire of Nicaea is traditionally accepted by historians as the legitimate continuation of the Roman Empire, mostly because in 1261 it recovered Constantinople, New Rome.[16] During the period between 1204–1261, however, there were four competing dynasties—aside from the Laskarids in Nicaea, these were the
Latinemperors of the "Flanders dynasty" in Constantinople,[17] the
Komnenodoukai of
Epirus and the
Megalokomnenoi of
Trebizond—equally claiming the east Roman emperorship.