Comparisons of the skull fossil with those of related species suggest the creature measured up to 40 feet (12 meters) in length.
"The skull bone of Sauroniops is very broad and particularly thick: This suggests an animal as big as Tyrannosaurus [rex]," Cau said. But without more fossils, "a more precise estimation of its size is currently impossible," the paleontologist added. (See "Meat-Eating Dinosaur Was Bigger Than T. Rex.")
The fossil also revealed that the dinosaur had a distinctive bump on its forehead, which sets Sauroniops apart from other carcharodontosaurs, according to the study, published recently in the journal Acta Palaeontologica Polonica.
This lumpy growth may have been used for head-butting clashes during male mating displays, the team speculates.
Though these top predators may have given each other the evil eye, it's quite possible they targeted different prey and weren't direct competitors, Cau said.
"Sauroniops lived along the banks of a large delta, under a hot and warm climate, very rich of fishes and crocodiles," he added. "The abundance of food may explain the abundance of predatory dinosaurs."