Smilax Bona-Nox

I told you I'd tell you what that thorny vine was, but that scientific name isn't helpful at all I'm guessing.
It's a brier, particularly a Saw (or Cat) Greenbrier. You might have guessed the brier part just by looking at the picture with the dense curtain of old briers making a thorny, nigh impassable, fence. The stems of this vine are tough and wiry with a smattering of spines that look like rose thorns. The leaves vary between heart shaped and triangular and it's 3-5 veins curve to fit the shape of the leaf. While it is not always the case this Greenbrier frequently has white or light green splotches on the leaves. They're about 2-5 inches long and 1-4 inches wide.
The flowers show in Spring they are clumped together and are green with curled back petals. The fruit ripens in fall and are dark purple, they look a lot like grapes - like 1/4 inch diameter grapes.
While other briers may have edible bits, I can find no such information on this particular kind. So the safety mantra goes, "don't eat it!"