What about the kamongo? Science hadn't heard about it until a few years ago. The kamongo lived way back in the Devonian age.
7 seconds sound clip from the Creature from the Black Lagoon (1954) movie soundboard.
You can hear this line at 00:40:31.229 in the Blu-ray version of the movie.
Quote context
[...]
- Crazy Goole, everybody called her.
- The unknown always seems unbelievable, Lucas.
- This is no legend, as you'll soon see for yourself.
- Interesting that the fossil I found was out of the same period.
- The kamongo was a fish that breathed air.
- That doesn't prove the possibility of a gill-man.
- I was sure I had him in my finder.
[...]