Not trying to sound like a jerk - but until you cut the head off a poisonous snake and dispose of it - they are still EXTREMELY DANGEROUS and can still bite. I have a very good friend that nearly died from a timber rattler bite while handling the severed head with about 1" of neck still attached. Head whipped around a bit him in the meaty part of his thumb. Spent 10 days in ICU, 10 vile's of antivenom and a tracheotomy... He's lucky to be alive.
Guy at our club was saying the same thing Saturday. The rattler that was dead in the road was still moving and he said it was still dangerous... I didn't chance it, so I parked on its head and cut the rattles off (it squirmed like hell when I put the knife to it)