Every early bishop of Rome on this site carries a span - Linus 67 to 79, Anacletus 79 to 92 - and those numbers are younger than the men. The Liber Pontificalis gives each of them a reign to the day, so many years, so many months, so many days, and Duchesne's edition showed where the figures come from: its compiler worked outward from the Liberian Catalogue of 354, which itself has firm consular dates only from the middle of the third century, and filled the earlier gaps by arithmetic to make the chain reach the apostles. The lengths are therefore a sixth-century reconstruction of a fourth-century reconstruction, and the days are decoration on both. This project shows the conventional years because a timeline needs somewhere to put a person, and marks the whole early stretch traditional for the same reason it marks the ordinals as a later church's arithmetic. Read the first two centuries of the Rome chain as an order with approximate spacing, not as a chronology. What is firm begins where the consular dates do.
Le Liber pontificalis: texte, introduction et commentaire · Le Liber pontificalis I, introduction, on the sources of the early lives