Finding in title is quoted from the abstract in the research paper, https://doi.org/10.1126/sciadv.abq7675

>The orientations of complexes built between 1100 and 750 BCE, in particular, represent the earliest evidence of the use of the 260-day calendar, centuries earlier than its previously known use in textual records.

... and from the linked content by Brian Handwerk, 6 Jan. 2023:

>Newly uncovered ruins along Mexico’s southern Gulf Coast appear to have been designed in alignment with the ancient timekeeping system.

>Aerial surveys using lidar technology revealed that hundreds of architectural complexes were aligned to facilitate timed observations of the rising and setting sun, moon and other celestial objects in line with this 260-day cycle.

>Scientists had suspected that the calendar, which is tied to cycles of maize agriculture and human reproduction, dated back this far.

>But the earliest documented evidence for its use was a glyph depicting “7 Deer,” one of the days in the calendar, as part of a third-century B.C.E. mural in Guatemala.

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>Since these cultures didn’t leave written records from earlier periods, scientists have found it exceedingly difficult to establish proof of prior calendar use—until this new large-scale discovery.

>These monumental assemblages of plazas, pyramids and platforms, some stretching more than half a mile, indicate the 260-day cycle was likely of central importance to the Olmec, Maya and other cultures since at least the key period of time around 1000 B.C.E.—when more widespread maize agriculture began to take hold in the region.

>“It is obvious that the orientations reflect a complex worldview in which astronomical knowledge conditioned by practical concerns was intertwined with religious concepts,” says co-author Ivan Šprajc, who studies Mesoamerican archaeology and archaeoastronomy at the Slovenian Academy of Sciences and Arts.