Two of the world's smallest monkeys have brought twin bundles of joy - and immense cuteness - into the world at Helensburgh's Symbio Wildlife Park, 45 kilometres south of Sydney.
Pygmy marmosets Pepper and Mateo became first-time parents when their babies were born in March.
The two baby monkeys each weighed less than 15 grams at birth - about the same as a tablespoon of butter, and roughly the size of a thumb.
They will only grow to about 100 grams, with pygmy marmosets being the smallest monkeys on earth.
A female marmoset is pregnant for about 135 to 141 days.
Once born, the babies are carried around on their parents' backs for several weeks.
"Mum will generally carry the babies for a week or so, then Dad will take over," Symbio primate and carnivore keeper and team leader Beth Beckwith said.
Mrs Beckwith said the father tended to be the primary caregiver, but other members of the family would also help carrying the babies on their backs.
The new twins at Symbio were just starting to come off the back now, Mrs Beckwith said, but still spent most of the time getting carried.
She said it would probably be another couple of weeks before they were off completely.
Once that happens, the two monkeys will be microchipped and their sex will be determined, then they will be named.
Mrs Beckwith said Symbio had been breeding pygmy marmosets for several years.
"We've been really successful with our breeding program with our pygmies," she said.
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In fact, new father Mateo was himself born at Symbio.
Mateo, Pepper and their babies just last week moved into a new exhibit with the endangered golden lion tamarins, in the first mixed monkey exhibit at the zoo.
Mrs Beckwith said the zoo had found that a family of pygmy marmosets usually maxed out at about seven before they started to kick members out, but being in a bigger home a larger family might be possible.
Pygmy marmosets were not endangered but were vulnerable in the wild, she said, with the illegal pet trade one of their biggest threats.
Pygmy marmosets are native to the Amazon in South America, through Peru, Colombia, Ecuador, Brazil and Bolivia.