The Tusoteuthis was a giant squid who once lived in the early Late Cretaceous period. Inhabitant to the North America's Western interior seaway, the Tusoteuthis i a carniovre eating almost anything smaller than itself. Things like small Cephalopods and fish. This organism is up to 20 ft. and only 6 meters. Sadly these guys are prey to Mosasaurs and Climolichtys.
Cretoxyrhina
Cretoxyrhina was a medium size shark that was sharp, and have enameled teeth to rip through its prey. (seen in the picture) From the Late Cretaceous seas period and home to the open seas. This organism can live for a long period of time because of its advantage to take down anything that comes it's way. It is 18 ft. and 5 meters wide, the same size of a great white shark! Since it huge and scary, this guy is a predator to mostly all the marine animals in the ocean. Don't mess with this baddie.
Archelon Ischyros
Archelon Ischyros was a sea turtle living in the Late Campanian to early Masstrichtian of the Cretaceous period. This organism was a carnivore; could only eat soft bodied organism. Archelon Ischyros are quite small creatures, measuring up to 4 ft and 4.9 meters wide. This organism had preys lurking from almost anywhere, prey like dinosaurs, primitive seabirds, and pterosaurs. Not quite lucky to be living in this era.
Bananogmius
Bananogmius are quite resemble to a modern fish. It got fins on both the top and bottom of it's body. It lived in the Late Cretaceous period, somewhere in the western seaway. It's a carnivore which mean eating little particles like plankton to live. It about 6 ft. tall and 2 meters wide. These guy is a prey to sharks and to anything bigger than them.
Caproberyx
Caproberyx was a small fish that have the ability to swim good due to his it's size. It 4 inches tall and 10 meters wide. It lived in the Late Cretaceous period. Making home to shallow tropical seas. It diet is quite simple, only eating anything smaller than itself like plankton.
Protostega
The Protostega looks similar to the animal we know as the turtle. It lived in the Late Cretaceous period. Making the seas it's home. Able to live on slow moving organisms, like starfish and jellyfish. Since it is an Omnivore it can eat seaweed and floating carcasses.
Dolichorhynchops
Dolichorhynchops was a short-necked marine reptilethat used long, flippers to fly through the water like a penguin. It also resembles our modern day Dolphin but are not related to them. This marine reptile was quick and agile, able to catch up to it's prey and eating them whole. Their large eyes helped them spot out small prey. The Dolichorhynchops grew 12 to 15 feet long. It was prey to the infamous Tylosaurus.
Protosphyraena
The Protosphyraena isa medium-size predatory fish of the Late Cretaceous seas. Sharing it's looks with the modern day swordfish with bladelike teeth positioned to stab fleeing prey. A fully grown adult Protosphyraena averaged between six and nine feet in length, fairly small compared to other predators of the sea.
Hainosaurus
Hainosaurus was a very large extinct marine reptile related to Tylosaurus. Mosasaurs became top marine predators and dominated the Cretaceous seas. The Hainosaurus was long and looked like a snake. Able to grow up to 40 to 60 ft in length. The Hainosaurus had paddles to move along the water propelling itself similar to how a modern snake moves. The Hainosaurus used its sharp teeth to prey on fish, squid, and other marine animals.
Squalicorax
This smaller shark preyed upon fish, but its serrated teeth were also well-suited to tearing apart carrion of all species. The Squalicorax left so many bite marks fossils including birds, fish, and other sharks. So many Squalicorax teeth are found that scientists believe the species was the most populous shark of its day. Other sharks may have been nudged toward extinction in the Late Cretaceous, but Squalicorax persisted until nearly the end of that period.
Ammonite
These ancient invertebrates were found throughout the Earth's oceans, where they lived as both predator and prey.Ammonoidea first appeared some 240 million years ago and died out when the dinosaurs did about 65 million years ago. These squidlike creatures had tentacles and sharp beaks, but lived in a sheel similar to a hermit crab. Some ammonites grew more than three feet. Ammonite shells contained several air-filled chambers that were used to regulate buoyancy