Feast your eyes on what a group of scientists call the Holy Grail of human evolution.

A team of researchers Tuesday unveiled an almost perfectly intact fossil of a 47 million-year-old primate they say represents the long-sought missing link between humans and apes.

Officially known as Darwinius masillae, the fossil of the lemur-like creature dubbed Ida shows it had opposable thumbs like humans and fingernails instead of claws.

Scientists say the cat-sized animal's hind legs offer evidence of evolutionary changes that led to primates standing upright - a breakthrough that could finally confirm Charles Darwin's theory of evolution.

"This specimen is like finding the Lost Ark for archeologists," lead scientist Jorn Hurum said at a ceremony at the American Museum of Natural History.

"It is the scientific equivalent of the Holy Grail. This fossil will probably be the one that will be pictured in all textbooks for the next 100 years."