Question: how do you know that the skeleton of lucy looked like that you only had about half of the skeleton

James Cole answered on 8 Jan 2019:

This is a really good question. You are right that there is only about 40% of Lucy’s fossilised skeleton, however, we do have an idea of how bones connect to each and what shape those bones form. From there we can reconstruct the whole skeletal framework. From there you can then reconstruct muscle attachments and get a reasonable idea of how our ancient ancestors may have looked. This link may also help to explain in more detail the answer to your question about Lucy: https://www.nature.com/scitable/knowledge/library/lucy-a-marvelous-specimen-135716086