This study compares the neck of Carnotaurus to that of Majungasaurus. According to them, Carnotaurus had a much more robust and less S-shaped neck than Majungasaurus.
What bothers me is that they suggest carnotaurines were "scavengers", which doesn´t fit with the recent studies that indicate speed adaptations in Carnotaurus at least. And isn´t it a mistake to begin with, trying to separate "scavengers" and "predators", especially when it comes to such large animals?
If it can hunt, it can certainly scavenge- and even the most devoted scavengers, like vultures, will hunt once in a while...