Maya Calendar Reform? Evidence from Orientations of Specialized Architectural Assemblages

Long before they devised a written calendar, the Maya articulated their seasons by means of an “orientation calendar” that consisted of visual alignments involving their architecture. One specialized set of buildings, Group Eat Uaxactún, Guatemala, in the Petén lowlands, has been regarded as the prototype of such a calendar. We present new data based on precise measurements made in the field at 12 Group E complexes and obtained for a number of additional sites from reliable maps where on-site astronomical fixes were acquired. Statistical analysis of the resulting 99 alignments supports the hypothesis that, at least at some stage of development, certain of these specialized complexes did indeed function astronomically. The earliest version of the orientation calendar seems to have developed in the Petén; it was focused on the solstices. A later orientation calendar seems to have functioned principally during the season leading up to the onset of rain and crop planting. It consisted of a division of the dry season into 20-day months prior to the first annual passage of the sun across the zenith (approximately May 10 in the Christian calendar). We argue that this later orientation calendar was derived from Teotihuacan during the Early Classic period (A.D. 278–593).