About Klingons...

[Catty-the-spy]

When did they get the foreheads?
I thought of it while watching "The Trouble with Tribbles", because they have normal foreheads there. When did the extension happen and why?

[Oni]

I think they got the foreheads in 'The Motion Picture.' because they had more money and where able to do that kind of Makeup.

[Catty-the-spy]

Did they ever give an explanation?

[Oni]

Most people thought that they it was just money and they did not think much about it.
But they did explain it in ST:ENT as it as some sort of experimental genetics thing that made them to look human, but a cure was made it just took time to cure.

[spookyfbi]

The explanation in the DS9 episode Trials and Tribble-ulations was "it is something we do not talk about." Lol, funny episode.