Quote:Is there any evidence that the Romans already used lateen sails?
Yessir!
For the use of Lateen sails in the Roman period cp.
Casson, L., 1985, Ships and Semanship in the Ancient World, Baltimore/London, 224f. 286f., fig. 190-182.
Viereck, W., 1975, Die Römische Flotte. Classis Romana, Herford, 300f., fig. 58/9.
The traces for the use of lateeners in the principate are scarce, but we have got more evidence for the late Roman period:
1.) Bishop Synesios probably once travelled in a lateener (there's a short appendix in Casson on this subject, however, Casson's ideas on this matter have already come under attack)
2.) the flagship of Belisarius in the Vandal expedition in 533 AD (Robert, don't kick me if the year's wrong!) was most likely a lateener according to Procopius, who wrote that the upper corners of the sails were painted red, so the numerous other vessels would know where the flagship was. Painting the upper corners red makes much more sense for lateen sails, than for square sails.
3.) the so called Malaga Dromon shows what is most likely a late Roman warship. According to
Alertz, U., 1995, Ein Graffito aus Malaga-ein Dromon Leos VI?, in: Das Logbuch 31, 60-66
the ship was a Byzantine one from the late 9th century. However, I am far from being convinced, since
a) by the 9th century Malaga had ceased to be a part of the Byzantine empire long ago
b) the vessel depicted is clearly a triacontere (30 oars ship). Alertz produced some reconstructional drawings with two rows of oars on each side, but this is nonsense, since the image from Malaga clearly shows one row of oars, and 15 oarports! Since triaconteres seem to have been the standard warships in the late Roman period, I fail to see why the Malaga image should not show one.
I hope to be able to add images of the Malaga dromon - if it doesn't work I'll try later.