Another primary consideration in introduction & eventual disappearance of Segmentata?

[Nathan Ross]

Do you doubt that source we have for 2,000 people dying per day in Rome at the plague's height, out of a city of one million?

It's probably true that this number could have died, on any number of days. But there are no accurate statistics for this period, so all we have is hearsay. Does this source tell us for how many days this level of mortality continued?

Again, I don't dispute the severity of the plague - nobody really does - but it's very hard to gauge accurately what kind of effect it might have had in subsequent decades.

Would armour, made out of metal, not continue to survive for ten to twenty years after it's production? Wouldn't some of the smiths who produced it, or their sons and apprentices, continue their work for a while? Also isn't it true that the latest examples of segmentata show simplification and worsening quality?

Why would it not survive? Technology wasn't just forgotten - if something ceased to be produced, there was either some reason why it could not be produced (lack of infrastructure, as seems to be the case sometimes in the 5th century) or it was obsolete. Since the Roman state had the capability to produce large quantities of good quality armour in the 4th century, we must assume that the segmentata was obsolete by this date.

The segmentata finds from Leon in Spain, dating to the later 3rd century, include both Corbridge and Newstead style fittings and do not, as far as I'm aware, show any decline in quality from earlier production.

Did literacy NOT drop during some time during the Roman period

As I've said, it probably did yes - although again it's very hard to gauge accurately. There was a decline in epigraphy from the 3rd century onward, and those later inscriptions we have (particularly from frontier areas) are often comparatively crude and incorporate spelling or grammatical errors. So the change probably happened during the third century some time. Social changes - the Antonine Constitution, and the subsequent incorporation of many part-Romanised provincials into the citizen pool, and the division of society into humiliores and honestiores - may have made widespread education and literacy less of a prized asset in the later era?

(incidentally, literacy in elite circles suffered no decline, as we see from the vast corpus of letters, philosophical works, orations and other documents from the later centuries)