Here is the conclusion, what evidence can we find that supports it?
Unfortunately, I can’t. Sebecids are known almost exclusively from cranial remains. From what I’ve been able to find, we seem to have almost no caudal remains at all, and no trackways seem to be known. However, judging from their apparently long legs, my uneducated guess would be that their tails were carried mostly off the ground, similar to the related baurusuchids. I’d suggest asking someone more knowledgeable on pseudosuchians than I, such as Darren Naish at Tetrapod Zoology.