Editing Roman calendar (section)

===Prehistoric calendar===
The original Roman [[calendar]] is usually believed to have been an [[observational calendar|observational]] [[lunar calendar]]{{sfnp|Mommsen & al.|1864|p=[https://archive.org/stream/historyrome00dickgoog#page/n242/mode/2up 216]}} whose months ended and began from the [[new moon]].{{sfnp|Michels|1949|pp=323–324}}{{sfnp|Grout|2023}} Because a [[lunar phase|lunar cycle]] is about 29.5 days long, such months would have varied between {{nowrap|29 and 30 days}}.<ref name=mommy/> Twelve such months would have fallen {{nowrap|10 or 11 days}} short of the [[solar year]] and, without adjustment, such a year would have quickly rotated out of alignment with the seasons<ref name=mommy/> in the manner of the [[Islamic calendar]]. Given the seasonal aspects of the calendar and its associated [[ancient Roman religion|religious]] [[ancient Roman festivals|festivals]], this was presumably avoided through some form of arbitrary curtailment or intercalation<ref name=mommy/> or through the suspension of the calendar during winter.
Against this, [[Agnes Kirsopp Lake Michels|Michels]] has argued that the early calendars used by Rome and its neighbors were more probably observational of seasonal markers in nature (the [[leafing]] of trees), animal behavior (the [[bird migration|migration]] of birds), and the [[agriculture in ancient Rome|agricultural cycle]] (the ripening of [[Agriculture in ancient Rome#Grains|grain]]) combined with observation of [[star]]s in the [[night sky]].{{sfnp|Michels|1949|p=330}} She considers that this more sensibly accounts for later legends of [[Romulus]]'s [[#Romulus|decimal year]] and the great irregularity in Italian month lengths recorded in [[Censorinus]].{{sfnp|Michels|1949|p=330}}<ref>[[Censorinus]], ''[[De Die Natali|The Natal Day]]'', [https://elfinspell.com/ClassicalTexts/Maude/Censorinus/DeDieNatale-Part2.html#topref94 Ch. XXII].</ref> Roman works on agriculture including those of [[Cato the Elder|Cato]],<ref>[[Cato the Elder|Cato]], ''[[De Agri Cultura|On Agriculture]]''.</ref> [[Varro]],<ref>[[Varro]], ''[[Res Rusticae|Farming]]''.</ref> [[Vergil]],<ref>[[Vergil]], ''[[Georgics]]''.</ref> [[Columella]],<ref>[[Columella]], ''[[De Re Rustica (Columella)|On Farming]]''.</ref> and [[Pliny the Elder|Pliny]]<ref>[[Pliny the Elder|Pliny]], ''[[Natural History (Pliny)|Natural History]]''.</ref> invariably date their practices based on suitable conditions or upon the [[rising of stars]], with only occasional supplementary mention of the [[#Republican calendar|civil calendar]] of their times{{sfnp|Michels|1949|p=330}} until the 4th or 5th century author [[Rutilius Taurus Aemilianus Palladius|Palladius]].<ref>[[Rutilius Taurus Aemilianus Palladius|Palladius]], ''[[De Re Rustica (Palladius)|On Farming]]''.</ref> [[Augury]], formal Roman [[ornithomancy]], continued to be the focus of a [[augur|prestigious dedicated priesthood]] until at least the end of the 4th century.{{sfnp|Wissowa|1896}} Although most Roman festivals in the historical record were closely tied to the [[nundinal cycle]] of the [[#Numa|later calendar]],{{sfnp|Michels|1949|p=322}} there remained several [[moveable feasts]] ({{lang|la|[[feriae conceptivae]]}}, "proclaimed festivals") like the [[Sementivae]] that were dependent on local conditions.{{sfnp|Michels|1949|p=331}} Michels suggests this was the original state of all ancient festivals, marking divisions between the seasons and occasions within them.{{sfnp|Michels|1949|p=331}}

{{anchor|Romulus|Romulan calendar|Calendar of Romulus}}