Analysis of information sources in references of the Wikipedia article "Azilian" in English language version.
The engraving on the Thaïs bone is a non-decorative notational system of considerable complexity. The cumulative nature of the markings together with their numerical arrangement and various other characteristics strongly suggest that the notational sequence on the main face represents a non-arithmetical record of day-by-day lunar and solar observations undertaken over a time period of as much as 3½ years. The markings appear to record the changing appearance of the moon, and in particular its crescent phases and times of invisibility, and the shape of the overall pattern suggests that the sequence was kept in step with the seasons by observations of the solstices. The latter implies that people in the Azilian period were not only aware of the changing appearance of the moon but also of the changing position of the sun, and capable of synchronizing the two. The markings on the Thaïs bone represent the most complex and elaborate time-factored sequence currently known within the corpus of Palaeolithic mobile art. The artefact demonstrates the existence, within Upper Palaeolithic (Azilian) cultures c. 12,000 years ago, of a system of time reckoning based upon observations of the phase cycle of the moon, with the inclusion of a seasonal time factor provided by observations of the solar solstices.
