Squalicorax is a large shark from the Cretaceous.
Walking with Dinosaurs[]
Squalicorax didn't appear in the main series.
Sea Monsters: A Walking with Dinosaurs Trilogy[]
Squalicorax was seen in the final episode in the Cretaceous in a deadly ocean (known as Hell's Aquarium) where a huge cloud of blood was in the sea and a group of Hesperornis were swimming away.
Squalicorax was shown to live alongside Xiphactinus and Halisaurus.