Scientists believe that 3.18 million years ago, a relatively young but mature adult female hominin fell from a tree in Africa and perished. Today, much of the world knows that hominin as Lucy, the most famous human ancestor.

The Australopithecus afarensis specimen was discovered in 1974 in Ethiopia. Lucy's bones remain the most complete skeleton of an erect-walking human ancestor yet assembled.

Until recently, researchers were at odds over how Lucy died. Anthropologists at the University of Texas, however, argue new 3D CT scans show fatal injuries sustained during a fall from a tree. The latest evidence is detailed in a new paper in the journal Nature.

"It is ironic that the fossil at the center of a debate about the role of arborealism in human evolution likely died from injuries suffered from a fall out of a tree," lead researcher John Kappelman, a UT Austin anthropology and geological sciences professor, said in a news release.

Lucy's latest scans revealed a fracture scientists hadn't noticed before, a series of fine bone fragments in her right humerus.

"This compressive fracture results when the hand hits the ground during a fall, impacting the elements of the shoulder against one another to create a unique signature on the humerus," Kappelman explained.

Researchers suggest Lucy walked upright on the ground, but still sought food and shelter in trees. The adaptations that allowed Lucy and other early hominins to take to the ground and stand erect came with costs, which likely included a diminished climbing ability.

Lucy's cumulative injuries suggest she fell from a height of more than 40 feet and hit the ground at a speed of at least 35 miles per hour. Her death was likely swift.

As with most scientific theories, there is likely to be dissent. Those who wish to examine the forensic evidence for themselves are free to do so. Scans of Lucy's shoulder and knee injuries have been made publicly available by the Ethiopian National Museum.

"This is the first time 3-D files have been released for any Ethiopian fossil hominin, and the Ethiopian officials are to be commended," Kappelman said. "Lucy is leading the charge for the open sharing of digital data."