Robotics manufacturer Boston Dynamics has long been developing a quadrupedic, autonomous — and headless — robot for hauling around military gear called the BigDog. But judging by this video, the BigDog is now practically lying submissive and moaning to itself in its crate. Because now the AlphaDog is in town.

On Tuesday, word broke of Boston Dynamics’ upgrade to the BigDog, known as the L3, for Legged Squad Support System. Funded by Darpa, it knew all the BigDog’s tricks — walking on uneven terrain, trotting beside soldiers, taking on heavy loads – but could just do more of them. It hauls up to 400 pounds, 60 more than the BigDog, on its mighty flat metallic back, and can trot around for 20 miles, while the BigDog tires out at 12. No wonder Boston Dynamics called it AlphaDog.

There’s also one big improvement, which you can see on this brand-new video, around the 1:06 mark. The factory prototype of the AlphaDog actually stands up after lying on its side. That’s not something the BigDog could do, though the earlier robot got pretty good at keeping its footing on uneven ground when soldiers cruelly tried to kick him over. Still, this new trick is impressive enough that you want to scratch behind the AlphaDog’s ears — until you remember that he still doesn’t have a head.

Right now, the AlphaDog is just a lab prototype. It’s still going to be a while before soldiers and Marines strap their newest robotic mule — er, dog — with gear and take him off to war. Boston Dynamics, Darpa and the Marine Corps aren’t planning a major test of the AlphaDog until 2012.

But don’t forget about the BigDog. Boston Dynamics also put together this video of his greatest tricks: