There's a certain amount of thrash of most competent death metal. And as much as I hate to admit it, excellent thrash bands do not merely hail from Baghdad By the Bay...there's Anthrax, Nuclear Assault, and OVERFUCKINGKILL from NY, Flotsam & Jetsam from AZ (a-hah!), Dark Angel from Los Angeles, Torture Squad and Sepultura from South America, and the absurdly awesome host of German thrash bands. And that's just the beginning...
Yeah, anyway, there's some thrash riffage here and there, but they're definitely some kinda death. Melodeath with testicles, I call it.