Dilophosaurus

Dilophosaurus, meaning "two-crested lizard," was named after the two distinct crests that sat atop the dinosaur's head and snout. These crests were likely covered in keratin, the same hardening protein that forms human nails. The keratin covering these crests may have been larger than what the skull fossils indicate, but they were too fragile to help Dilophosaurus in combat. However, the crests may have been colorful and used to attract mates. 

Dilophosaurus' build suggests it was a hunter of small vertebrates. They had a notch in their upper-jaw that would have combined with their long, curved teeth to snatch and hold onto prey. Short, saw-like teeth in the back half of their jaws allowed them to slice into the flesh of their prey. 

Though smaller than T. Rex, Dilophosaurus was one of the largest land carnivores of the Early Jurassic Period. This trait would have made them an apex predator, controlling the populations of smaller animals in its geographic range.