"The Garden of Earthly Delights" (sometimes called "The Millennium") is probably the most famous work by the 15th century painter Hieronymus Bosch. The content of the triptych is open to interpretation but the three panels are generally agreed to follow a temporal progression. Given that the two side panels depict the beginning and the end of time it could be considered a timeline - it's definitely an early example of sequential art. To find more clues I would need to examine the content of those panels up close.
This paining is just one of many great works of art that hang in Madrid's Prado museum. A few years ago, if I wanted to examine it in detail, I had two options: I could purchase a print and hope the reproduction was relatively faithful. Or I could get on a plane and fly to Madrid. There is now a third option. More and more art is being imaged at extremely high resolutions; you may remember I covered Lumiere Technology's high resolution multi-spectral analysis of classic artwork. This imagery can now be viewed using innovative zooming interfaces by anyone with a web browser.