A small, lemur-like creature may have been an early ancestor of monkeys, apes, and humans. A magnificently preserved fossil dating from 47 million years ago reveals an animal that had, among other things, opposable thumbs, similar to humans’, and unlike those found on other modern mammals. It has fingernails instead of claws. And scientists say they believe there is evidence it was able to walk on its hind legs.
(...) The fossil was first discovered in 1983 in the Messel Shale Pit, an old quarry near Frankfurt, Germany that has long been a World Heritage Site because of its rich fossil beds. The specimen was excavated by private collectors but was then divided into two parts and sold; it was only two years ago that scientists reassembled the complete fossil and began studying it. Described by the Times as the “most complete fossil primate ever discovered,” the specimen is a juvenile female the size of a small monkey. Only the left lower limb is missing, and the preservation is so remarkable that impressions of fur and the soft body outline are still clear. The animal’s last meal, of fruit and leaves, remained in the stomach cavity.
(...) The new research adds to an argument over which of two groups of ancient primates was the evolutionary jumping off point for apes and humans: Was it the tarsidae group, which gave rise to the big-eyed tarsiers found in southeast Asia, or the adapidae group, the precursors of the lemurs found in Madagascar? The latest discovery bolsters the less common position that our ancient ape-like ancestor was an adapid, the believed precursor of lemurs.
Ida (pronounced EE-duh) is the most perfectly preserved primate fossil in the world. Paleontologists, scientists who study fossils, estimate that Ida died 47 million years ago. Ninety-five percent complete, she is the most complete primate fossil ever found. By comparison, the famous “Lucy” fossil, Australopithecus afarensis, is only 40 percent complete.
Ida was a small primate, about 9 months old when she died. From end to end she is only 58 centimeters (23 inches) long, about the size of a small house cat. Her body is 24 centimeters (9 inches) long. Ida's legs were longer than her arms, indicating she was a leaper. X-ray scans show she was a female. Ida’s remains also show she had a broken right wrist. She didn’t die of a broken wrist, but it almost certainly contributed to her early death.
Ida had large eye sockets, which suggests she was nocturnal. Nocturnal animals are active mainly at night. The shape of Ida’s teeth suggests she was a vegetarian. However, scientists didn’t have to guess what she ate. Her last meal—fruit—was still preserved in her gut millions of years after she ate it.
Ida had long fingers and toes, and opposable thumbs. Her hands show she had rounded fingertips with nails, not claws. Rounded fingertips with nails are classic primate features.
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