The ‘top hat’ look for the figure on f.5v appears to me very like that shown on Seleucid coins. The first example was made for Antiochus I, one of Alexander’s generals and the first ruler of the Seleucid kingdom after the territories taken by Alexander were divided. The obverse shows the Dioscuri seated.
The second example (detail as header) is attributed to the reign of Antiochus VII (138 to 129 BC), known as Euergetes. The image is very crisp and clear, uploaded to a wiki article on Antiochus by ‘Uploadalt’. At the time of writing, wildwinds does not have an example of it. Note the floral emblems to each side. The rose signified the circuit of earth and the ivy or vine-leaf the ways of the sea. The ‘vine-road’ motif survives to appear in western manuscripts of the medieval period, the more relevant instances being those coloured white on blue, or where the motif is made an ornament over a ground of gesso or gold. In local Syrian tradition the Dioscuri are represented only by a pair of baetyls, each sometimes topped by a star.