Fossil footprints still are puzzling scientists: Bear or ancient human?

FILE - Dr. Mary D. Leakey, of the National Geographic Society in Washington, Feb. 24, 1978 holds hands near a picture of a footprint found at Laetolil, Tanzania. It is believed the track belongs to a hominid who lived between 34 and 3-¾ million years ago and was about 4-foot tall. rehistoric footprints that have puzzled scientists since the 1970s are getting a second look: Were they left by extinct animals or by human ancestors? When famed paleontologist Mary Leakey first uncovered the footprints in Tanzania 40 years ago, the evidence was ambiguous.( AP Photo/File)