Post-mortem contraction of the posterior neck ligaments.
5 seconds sound clip from the Jurassic Park (1993) movie soundboard.
You can hear this line at 00:06:45 in the Blu-ray version of the movie.
Quote context
[...]
- Should bring an immediate return.
- You shoot the radar into the ground, and the bone bounces the image back. Bounces it back...
- It's a little distorted, but I don't think it's the computer.
- Post-mortem contraction of the posterior neck ligaments.
- It's five, six feet high. I'm guessing nine feet long.
- Dr. Grant's not machine-compatible.
- Hell, they've got it in for me.
[...]