This most interesting and rare surname is of Old Gaelic origin, and is a patronymic form of the Irish surname Kiernan, which itself is the Anglicized form of the Gaelic "O'Ciarain, O'Ceirin", composed of the Gaelic prefix "O", male descendant of, and a personal name from "ciar", black or dark brown. This sept was originally in possession of the greater part of the present barony of Costello in County Mayo, but during the edieval period their importance diminished, while an influential branch settled in County Clare about 1420. An inquisition in 1609 describes them as erenaghs (holders of church property) of Killaghtee in the diocese of Raphoe, and in the census of 1659 they are located in County Sligo. Today Kieran and O'Kieran are found mainly in County Mayo, where the name is also Anglicized as Kearns, O'Kerin, Kerrane, Kerin and Kearon. Thomas, son of Edward and Hannah Kerrans was christened on December 20th 1734, in Dublin, and Thomas Kerans married Charity Hard on May 21st 1805, in London. The Coat of Arms most associated with the family depicts a silver chevron with three red leopards' faces on a green shield, and the Motto is "Fidens et Constans", translating as "Courageous and Faithful". The first recorded spelling of the family name is shown to be that of Dorby Keran, which was dated April 6th 1654, marriage to Isma Beshell, at St. Michen, Dublin, Ireland, during the reign of Oliver Cromwell, known as "The Great Protector", 1649 - 1658. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.