Tropylium wrote:The Latin development *-sr- → /-br-/ seems to demonstrate that it has fortified Proto-Italic fricatives, not retained PIE stop values. It doesn't follow though if this was thru *-θr- → *-fr- or *-zr- → *-ðr- → *-vr-.
Don't some Celtic languages have sr > fr?
Yes, it seems, at least word initially.
PIE *sregh- -> Gaul *frogná, OBret fron, MW ffroen, OIr srón
PIE *srew- -> OCo frot, OBret frut, MW ffrwd, OIr sruth
PIE *tem-[esla?] -> Lat tenebrae, OCo. tiwoulgou, OBret. temoel, OW timuil, W tywyll, Olr. temel
Cf. also Gaul.
Phroudis [Hydronym], which is sometimes claimed to show that Gaulish
shared the Brittonic change of *sr- > *fr-.
(All from Leiden's Celtic Etym Dict)