The skull of a species first recognized in 1927, Carcharodontosaurus saharicus, was found in the Sahara in southeastern Morocco. Its name means "shark-toothed reptile from the Sahara." Before this, only fragmentary remains of this dinosaur have been recovered. The skull measures 5 feet 4 inches and may be larger than the largest skull of T. rex. The brain cavity of C. saharicus appears to be about half the volume of that of T. rex, indicating that T. rex may have been a great deal smarter than C. saharicus.
In Argentina, an entirely new species was unearthed, called Gigantosaurus carolinii, named after its discoverer. The skull of this new species is slightly longer than that of any known tyrannosaur skull. Comparisons of other bones indicate that G. carolinii may have been 3 tons heavier than T. rex. However, scientists note that Tyrannosaurus is still longer limbed and taller than both Carcharodontosaurus and Gigantosaurus. These discoveries of large predatory dinosaurs in South America and Africa are changing current concepts of the evolution of dinosaurs and movement of the continents during the Cretaceous.
Source: "Fossil Is Discovered of a Terror That Dwarfed T. Rex" by John Noble Wilford, New York Times May 17, 1996.