Big role for 'oz baby.
The rare red titi monkey is 3ins long and weighed 'oz at birth.
Deforestation in its natural habitat of South America, from Colombia to Brazil, Peru and north Paraguay, has led to a dramatic drop in its numbers.
The repopulation of the species is made more difficult because titis are monogamous, mating for life.
The monkey is so small that keepers at Twycross Zoo will have to wait several weeks before discovering its gender.
Zoo spokesman Kim Riley said: "The birth is exciting and we hope it will mark the beginning of a successful breeding programme.
"The red titis are rare and this is the first time this zoo has had one born here."
The zoo, near Atherstone, has the world's largest collection of primates.
HOLDING TIGHT... the rare red titi monkey on its mother's back, the first of its kind to be born in the UK.