Pantera is groove metal, man.

I mean, Vulgar Display wasn't a groove metal album, but Pantera was a groove metal band. At the core, groove metal was bands doing what thrash bands did with an ear for doom metal. Take a heavy riff that makes you want to flail around and get the tempo down to where you can stomp with it. Make something that sounds mean sound heavy. Drive the riff right into their fucking skulls. That's what Pantera did, and they were the first to do it.

If you google "groove metal" Pantera is the first band to show up, haha. I think you need to rethink what you said.