A new species of ancient wide-mouthed frog once prey to caveman hunters 100,000 years ago has been unearthed by scientists in Argentina.

Fossil hunters discovered the remains of the amphibian's skull on a routine field trip to San Pedro in Buenos Aires, the country's capital.

Leader Julio Simonini found the fossil when he noticed small bones embedded in a Pleistocene era rock.

The newly discovered amphibian - shown in an artist's model - belongs to the group of escuerzos, carnivorous amphibians.

The group of frogs hunt by movement and can eat any smaller animal that passes by.

The species lived during the Pleistocene era -a historic period that lasted from c. 2.58 million to 11,700 years ago.

Experts are to name the new species after Simonini, who found it.