"I'm fairly sure one of the talking Ravens of the North is referred to at some point in LOTR. To be certain, I'd have to and look it up, but isn't Carc the raven in TH, & Roac, son of Carc mentioned in LOTR?"
I'm now about a third of the way into Return of the King on my sixth or seventh reading, and neither Roac nor Carc has been mentioned. I don't BELIEVE there's even been any mention of ravens so far, unless it was the flocks of birds seen over the fellowship in Hollin.
I'm saving my identification of the animal I mentioned for tomorrow, to leave further time for anyone else to come up with it.