PHILADELPHIA (CBS) – The Philadelphia Zoo has some new arrivals in its Rare Animal Conservation Center.

A set of pied tamarin twins are now on display.

Lead keeper Anna Halko-Angemi says they were born on November 3rd to mom “Twiggy” and dad “Socks.”

(Closeup: baby tamarin rides on mother's back at Philadelphia Zoo.)

The arrival of the twins is good news to the zoo.  Pied tamarins are natives of the Amazon rainforest, and Halko-Angemi says there are not many left.

“They are endangered,” she explains.  “And it is also exciting for the Philadelphia Zoo because we are the first zoo in North America to breed this species.”

(Durham:)  “What is like taking care of them?”

(Halko-Angemi:)  “It’s very exciting.  You never know what you are going to come into, day by day.  For example, we walked in here one morning and there were twins on the mother’s back — very exciting!”

The twins have white fur on their heads and cheeks but will eventually lose it as they mature. Their gender is not yet known, so they have not been named yet.

Reported by Michelle Durham, KYW Newsradio 1060.