Lara and Lucy are emperor tamarin twins born at the Denver Zoo on July 9. Their father died before they were born, and their mother died July 20 of cancer.

So zookeepers and veterinary staffers are stepping in to make sure the girls get the care they need in the nursery.

“It was such a shock to lose Yana (their mother), as she did not show signs of illness. She was a wonderful mother and we are trying to fill her role in every way, providing the best care and nutrition for these twins,” curator of primates and carnivores Beth Jo Schoeberl said in a news release. “So far, they are doing great and we are pleased with their progress.”

Zoo visitors can see the twins being fed daily at 10:30 a.m. and 4:30 p.m.

The twins are fed from a syringe with a nipple. They also get some chilled vegetables to chew on while they are teething. So far, “feedings have gone well and the tamarins continue to gain weight,” the zoo release said.

According to zookeepers, the twins’ older brother, Paddy, has been very attentive to the newborns, as well.

Zoo staffers are doing their best to fill the functions of a mother monkey. They created a “baby bouncer” device to “encourage the twins to hang on to a moving replica of mom,” the release said. The baby monkeys need this for muscle strength and coordination.

In the forests of Central America, the emperor tamarins forage the trees and forest floor for a variety of insects, fruit and nectar. Many other species of the tamarin can be found in Central America.

The monkeys typically live in family groups of three to eight individuals, with the burden of raising the young shared by all the adults.