Femur Heads (image) Penn State Share Print E-Mail Caption Two femora, on the left is a large, presumably male specimen and on the right is Lucy. The difference between these two gives the impression of a large size differences between the sexes. However, inclusion of the many intermediately sizes specimens from this species indicates that the size variation is similar to moderately dimorphic humans. Credit Philip Reno, Penn State Usage Restrictions non commercial use only Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.