the primary purpose of adoption was to preserve the name and status of the adopter, an adopted son would usually assume both the praenomen and nomen of his adoptive father, together with any hereditary cognomina, just as an eldest son would have done. However, adoption did not result in the complete abandonment of the adopted son's birth name. The son's original nomen (or occasionally cognomen) would become the basis of a new surname, formed by adding the derivative suffix -anus or -inus to the stem. Thus, when a son of Lucius Aemilius Paullus was adopted by Publius Cornelius Scipio, he became Publius Cornelius Scipio Aemilianus; in his will, the dictator Gaius Julius Caesar adopted his grandnephew, Gaius Octavius, who became known as Gaius Julius Caesar Octavianus. Filiation Apart from the praenomen, the filiation was the oldest element of the Roman name. Even before the development of the nomen as a hereditary surname, it was customary to use the name of a person's father as a means of distinguishing him or her from others with the same personal name, like a patronymic; thus Lucius, the son of Marcus, would be Lucius, Marci filius; Paulla, the daughter of Quintus, would be Paulla, Quinti filia. Many nomina were derived in the same way, and most praenomina have at least one corresponding nomen, such as Lucilius, Marcius, Publilius, Quinctius, or Servilius. These are known as patronymic surnames, because they are derived from the name of the original bearer's father. Even after the development of the nomen and cognomen, filiation remained a useful means of distinguishing between members of a large family. Filiations were normally written between the nomen and any cognomina, and abbreviated using the typical abbreviations for praenomina, followed by for filius or filia, and sometimes for nepos (grandson) or neptis (granddaughter). Thus, the inscription means "Spurius Postumius Albus Regillensis, of Aulus the son, of Publius the grandson". "Tiberius Aemilius Mamercinus, the son of Lucius and grandson of Mamercus" would be written . The more formal the writing, the more generations might be included; a great-grandchild would be or for pronepos or proneptis, a great-great-grandchild or for abnepos or abneptis, and a great-great-great-grandchild adnepos or adneptis. However, these forms are rarely included as part of a name, except on the grandest of monumental inscriptions. The filiation sometimes included the name of the mother, in which case gnatus would follow the mother's name, instead