The Reckoning of the Realm
From The Regnum Animale by Bishop Vitellus of Oaken:
While the life of the average Fauna may seem like endless cycles, the Church has recorded the passing of years since the days of the Kindling, when Talisid and the Five Companions brought the word of the Undying Flame to the Twelve Clades at Arkhaven. Since that blessed event caused the establishment of the Regnum Animale, the final reign of Fauna over the earth, we mark the passage of years beginning with that date. At the time of this writing, it is 4511 Regnum Animale, or R.A.
Another, more common method of marking the passage of years is from the coronation of the King. When our last great monarch, King Glyndwir the Gold, fell in battle against the Reptilians at Est Izlon, it was the ninteenth year of his reign; thus, it was recorded as XIX Glyndwir. However, it has been three years since Glyndwir's fall, so at the time of this writing we are in the third year of Interregnum (III Interregnum).
It is said that the Avians of High Aquilaria have a far more complex system of marking time's passage, but it is of little use to the purposes of those who do not indulge in the practice of magic. It is indeed complicated, but it may also be more precise a system than our own, taking into account several esoteric factors. However, for the purposes of this record it may be safely omitted. – Benevolus