would seem that more than one author goes for the date 1882 - although whether that is due to this being the date when Sowerby are quoted as having introduced rubine, I don't know - presumably this particular design of bowl was produced over a number of years, in its various guises.
My personal thoughts are that this would have been a late C19 item, rather than C20, but I'm only guessing, and should really look in the Thistlewood CD catalogue and be accurate.
The factory obviously went in for dolphin feet in a big way................ Sheilagh Murray comments that in addition to rubine, the dolphin bowl was produced in black, canary yellow, olive green and malachite colours - with an experimental bowl produced with a crenated (?) edge and different body patterns - plus a gold lustre surface (iridescent glass).
Assuming this last description refers to carnival glass, then the date of that version would have been C20, rather than C19.
Although not mentioned by Murray, the bowl can be found in tricorn shape in Queen's Patent Ivory Ware.
Murray also says that in it's rubine form, bowls show a colour change from amber to red, and says that this was created by re-striking the bowls.
Re-striking amber shades does of course produce deeper reds - see amberina etc., although can't see any mention of re-striking in other books - is it possible that the colour variation might occur depending on the thickness of the glass?? Is pressed glass re-struck?
Hope the op won't object to my posting a dolphin bowl in rubine, plus two other Sowerby bowls which I've always assumed were rubine (they are certainly Sowerby) - although they don't show the colour variation as seen in the dolphin bowl.
Would be interesting to see a picture of the op's bowl, bearing in mind there are several different shapes.