The Miocene was the first epoch of the Neogene period (23-2.5 million years ago), followed by the much shorter Pliocene epoch (5-2.6 million years ago); both the Neogene and Miocene are themselves subdivisions of the Cenozoic Era (65 million years ago to the present). Climate and geography.
The dictionary meaning of the word Digress is 'to leave the main subject temporarily in speech or writing.' or simply deviate. As you say,I digress means  I am straying from the main subject right now. . Like in this sentence - 'I need to digress a bit to let the ink dry.'. Hope this helps :)
noun, plural dignities. 1. bearing, conduct, or speech indicative of self-respect or appreciation of the formality or gravity of an occasion or situation. 2. nobility or elevation of character; worthiness: dignity of sentiments. 3. elevated rank, office, station, etc. 4. relative standing; rank.