What caused the Super Predators to vanish by the late Cretaceous (excepting T. R

I think it should be of, What caused the super predators in the South to vanish by the L. Cretaceous? In the North, the previous super predators, the allosaurian dinosaurs, were displaced by the tyrannosaurs. When a tyrannosaur moved into the area, it ultimately out-competed every other large predator in the area and became the super predator. The South is a different story. The big tyrannosaurs never reached here. The large predators of the South never seemed to have had one group be the major super predators. It was a constant struggle. Primarily between the allosaurs, spinosaurs, and abelisaurs. For some reason I can't explain, by the L. Cretaceous, the spinosaurs and allosaurs of the south went extinct. Perhaps the abelisaurs survived because, unlike the spinosaurs and the allosaurs, they never achieved super predator status. Either way, with the extinction of the spinosaurs and allosaurs, the door was open for the abelisaurs to take over. The North is easy enough to understand. The ceratosaurs were the super predators, followed by the allosaurs, and finally the tyrannosaurs. The tyrannosaurs were the unrivaled rulers of the North, that's a fact. The South on the other hand, is not so easy. There was never really any progression. It's a mystery that may never be fully understood. Super Predators of the North(Minimum Size= 40 ft, 5 tons) [img]http://www.rareresource.com/photos/dinosaur-gallery/Tarbosaurus89.jpg[/img] Tarbosaurus(36-40 ft, 5-6 tons) [img]http://ichef.bbci.co.uk/naturelibrary/images/ic/credit/640x395/t/ty/tyrannosaurus/tyrannosaurus_1.jpg[/img] Tyrannosaurus(40-50 ft, 7-10 tons) Super Predators of the South(Minimum Size= 40 ft, 5 tons) [img]http://news.bbcimg.co.uk/media/images/55131000/jpg/_55131854_5carcharodontosaurus.jpg[/img] Carcharodontosaurus(40 ft, 5-6 tons) [img]https://upload.wikimedia.org/wikipedia/commons/2/2b/Spinosaurus1DBa.png[/img] Spinosaurus(56 ft long, 5-7 tons) [img]http://members.tripod.com/~Dinosauria/Giganotosaurus.gif[/img] Giganotosaurus(43-46 ft long, 7-8 tons) Sizes based on my estimates

The huge prey died out, making the huge Carnivores die out, only the smaller Carnavors with less if an appetite lived.

The Earth was changing, the living conditions were changing, everything was changing. Those who were unable to adapt, died out. New competition was coming. As Rex Fan said, the Tyrannosaurs basically took over the North.