Sussex Zoo welcomes the arrival of world's tiniest monkey

The tiny tot is a pygmy marmoset which was discovered by keepers at Drusillas Zoo Park in Alfriston on August 5, a micro ball of fur clinging to mum Rosie’s back.

Pygmy marmoset newborns measure around 3cm, roughly the size of a human thumb. They reach around 12 to 15cm in length and 100g in weight when fully grown.

Mum Rosie arrived at the zoo on January 30 and keepers were hopeful that her pairing with resident male Ben would result in successful breeding efforts.

Keepers observed that Ben appeared to be "smitten" with Rosie from the moment she arrived, and it seems she reciprocated his feelings as the baby must have been conceived about six weeks after their union.

The new arrival with mum, Rosie (Image: Drusillas Park Zoo) Until now, Drusillas had not welcomed a pygmy marmoset baby in over a decade and the news represents a tiny but crucial boost for the species.

Drusillas is now asking people to suggest a name for the mini monkey.

Zoo manager Mark Kenward said: “We had been hoping for the arrival of a pygmy infant for a long time so it’s wonderful news to announce. We’re always particularly proud when we welcome the birth of a species at risk of extinction and it’s a privilege to play our part in conservation.

“Pygmy marmosets are typically quite shy but Rosie has always been more confident in her nature, coming over to investigate what’s going on, which has made it easier for us to carry out observations on the infant who is doing brilliantly.”

Pygmy marmosets are the smallest true monkey and one of the smallest primates in the world, native to the rainforests of South America. The species is classified as vulnerable on the ICUN Red List of threatened species due to habitat loss and the exotic pet trade where they have become popularly known as "finger monkeys", a worrying trend seeing marmosets taken prematurely from their mothers and sold as "cute" accessories.