Paul Sereno, a resident paleontologist at National Geographic has been scouring the arid regions of the Sahara desert for many years, in search of crocodile fossils. Now his findings of five species of the ferocious creatures that roamed the Earth 100 million years ago, have been used to create an amazing documentary entitled 'Crocs' Eating Dinosaurs"

The remains of the five crocodiles which hung out with the dinosaurs and often hunted them for lunch, were found close to the modern day Niger and Morocco - in the same vicinity where Dr Serano and his team had found 'Supercroc' an 8 ton 40ft long crocodile, believed to be the world's largest crocodile, that lived during the same era.

Unlike modern-day crocodiles, these Dino-crocs were able to walk upright with their hands and legs on their sides like land mammals. They were therefore not only very good swimmers, but also, fast runners.

Based on the bones and teeth of each species, the scientists believe that they all had different diets and behavior patterns, that enabled them to co-exist with each other. The five species of these never or rarely before seen crocodiles have been classified as follows:

Boar Croc (Kaprosuchus saharicus) - Found in the Niger delta, the scientists believe this was the most dangerous one of all - One that probably attacked the dinosaurs. The 20ft. long upright carnivore sported an extra 'armor' on its snout that helped it ram victims and had not one - but three sets of fangs, that resembled boars teeth, for slicing up the meat!

Rat Croc (Araripesuchus rattoides) - A smaller upright crocodile species, believed to be just 3-foot long and an omnivore that survived on grubs and plants.

Pancake Croc (Laganosuchus thaumastos) - Named for its large three-foot long flat head, this 20ft long croc had spike-shaped teeth on its lower jaw. Primarily a fish-eater, this astonishing creature could stand still for hours with its mouth open, waiting for prey to glide in.

Duck Croc (Anatosuchus minor) - A smaller species that hung around mudbanks and shallow water searching for fish and grub, this three-foot long creature had an overhanging snout and a long, sharp nose.

Dog Croc (Araripesuchus wegeneri) - Named because of its soft dog-like nose, this was also a smaller crocodile and an omnivore that lived off grub and fish and was comfortable both on land and in water.

The modern crocodile is believed to have evolved about 80 million years ago, surviving the extinction that wiped dinosaurs out of this world. There are currently believed to be about 23 species crocodilian (alligators, crocodiles and caimans) left in the world and most of them live within 2,600 miles of the Equator! The largest living species is the saltwater crocodile that grows up to 23ft long and can hold its breath underwater, for over an hour!

When Crocs Ate Dinosaurs is scheduled to be aired on the National Geographic Channel on Saturday November 21st at 6.00 pm and 9.00pm - Be sure to watch it!