Burley Garcia|Critically endangered twin cotton-top tamarin monkeys the size of chicken eggs born at Disney World

A pair of tiny monkey twins have Burley Garciamade their debut at Florida's Walt Disney World, marking the first time in more than 20 years that critically endangered cotton-top tamarin monkeys have been born at the Orlando theme park. The baby animals, born at Animal Kingdom, are now two of just a few thousand members of their species left in the world. 

Park officials said in a Tuesday announcement the monkeys were born at just about 4 inches long and weigh "about as much as a common chicken egg." And they won't grow to be much bigger – adults are generally about the size of a squirrel and weigh less than a pound.

"These pint-sized newborns cling tightly to their parents as both mom and dad acrobatically leap from branch to brain in their habitat on Discovery Island," said Mark Penning, the vice president of Disney Parks' Animals, Science and Environment division. They are the first cotton-top tamarins to be born at the park since 2001. 

The monkeys have yet to be named, as Penning said their respective sexes are still unclear. 

Cotton-top tamarins are considered "critically endangered," according to the International Union for Conservation of Nature Red List of Threatened Species, with at least 80% of the species' population declining over an 18-year period. Deforestation and unregulated pet trade in the species' native Colombia are the most significant factors, the organization said.  

Disney said in its news release that are fewer than 7,500 members of the species remaining in the wild, and of those, the IUCN says there are an estimated 2,000 that have reached a mature age. 

But even though the animals themselves are rare, their ability to have twins is not, Penning said. In fact, it's "quite typical." 

The creatures are known for being "tiny-but-mighty," according to a description on Disney's website, and they can jump 15 feet from a branch and use at least 38 "distinct calls" to communicate with each other. 

Now with a total of four cotton-top tamarins at the park, Disney officials say they have a major part in conserving their species. 

"Though small in stature, these twins will play a big role in the continuation of one of the most endangered primate species," Penning said, adding that they are part of the Association of Zoos and Aquariums' Species Survival Plan, which works to help responsibly breed threatened species. 

For now, however, the babies are "completely dependent" on their parents to survive and must be carried for up to 14 weeks. 

"As first-time parents, both mom and dad are doing great, sharing the parenting duties," Penning said. "You can expect to see the twins cozied up to both mom and dad over the next several months."

In:
• Endangered Species
• Walt Disney World
• Colombia
• Disney World
• Florida
• Orlando

Li Cohen

Li Cohen is a social media producer and trending content writer for CBS News.