Final answer:
Lucy is a nickname for a fossil specimen belonging to the species Australopithecus afarensis, discovered in 1974 and significant for being one of the most complete australopithecine skeletons.
Step-by-step explanation:
The fossil specimen nicknamed "Lucy" is an example of Australopithecus afarensis. Discovered in the Afar region of Ethiopia by American paleoanthropologist Donald Johanson in 1974, Lucy's fossil was given the identification number KNM-AL-288, denoting the Kenya National Museum and the Afar locality where she was found. Dated to roughly 3.75-2.8 million years ago, this skeleton was significant as it was one of the most complete fossils found for an australopithecine, with about 40 percent of the skeleton recovered. Belonging to a species that demonstrates a reduction in dentition and jaw size, A. afarensis had smaller canines and molars compared to apes, but larger than those of modern humans, and had a brain size roughly equivalent to that of a modern chimpanzee.