15 September 2011 Last updated at 09:30 ET

Big fossil croc may have competed with giant snake

The ancient environment seems to have been dominated by reptiles

The fossilised remains of 6m (20ft) -long extinct crocodile relatives have been discovered in a mine in Colombia.

The massive croc would have lived at the same time as the world's largest-known snake and may even have competed with it for food.

The remains were discovered in the Cerrejon mine of northern Colombia, one of the world's largest open-pit coal mines.

A US team has described the specimens in the journal Palaeontology.

The freshwater creature, named Acherontisuchus guajiraensis, inhabited an ancient rainforest ecosystem some 60 million years ago, during Palaeocene times.

The environment was dominated by reptiles, including giant snakes, turtles and crocodiles. This is the second crocodile relative excavated from the Cerrejon mine.

Temperatures at this time were much higher than today, and scientists say that studying the diversity of animals in this ecosystem could help them understand the impacts of a warmer climate in the future.

It lived alongside a giant snake known as Titanoboa, which is thought to have grown to about 13m (42ft) in length.

The scientists say that A. guajiraensis was specialised for eating fish, which means it probably would have competed for food with Titanoboa.

"The younger individuals were definitely not safe from Titanoboa, but the biggest of these species would have been a bit much for the [13m] 42-foot snake to handle," said lead author Alex Hastings, from the Florida Museum of Natural History.

The new species belongs to a group of crocs known as dyrosaurids, believed to be primarily ocean-dwelling, coastal reptiles.

The researchers say the new adult specimens challenge previous theories that the animals would only have entered freshwater environments as babies before returning to the sea.

The croc was comparable in size with the largest examples of living crocodiles and alligators today.