Editing Australopithecus afarensis (section)

===Lower limbs===
The australopith pelvis is [[pelvis#Caldwell–Moloy classification|platypelloid]] and maintains a relatively wider distance between the [[hip socket]]s and a more oval shape. Despite being much smaller, Lucy's [[pelvic inlet]] is {{cvt|132|mm}} wide, about the same breadth as that of a modern human woman. These were likely adaptations to minimise how far the [[centre of mass]] drops while walking upright in order to compensate for the short legs (rotating the hips may have been more important for ''A. afarensis''). Likewise, later ''Homo'' could reduce relative pelvic inlet size probably due to the elongation of the legs. Pelvic inlet size may not have been due to fetal head size (which would have increased [[birth canal]] and thus pelvic inlet width) as an ''A. afarensis'' newborn would have had a similar or smaller head size compared to that of a newborn chimpanzee.<ref name=Gruss2015/><ref>{{cite journal|first=Y.|last=Rak|year=1991|title=Lucy's pelvic anatomy: its role in bipedal gait|journal=Journal of Human Evolution|volume=20|issue=4|pages=283–290|doi=10.1016/0047-2484(91)90011-J|bibcode=1991JHumE..20..283R }}</ref> It is debated if the platypelloid pelvis provided poorer leverage for the [[hamstring]]s or not.<ref name=Gruss2015>{{cite journal|first1=L. T.|last1=Gruss|first2=D.|last2=Schmitt|year=2015|title=The evolution of the human pelvis: changing adaptations to bipedalism, obstetrics and thermoregulation|journal=Philosophical Transactions of the Royal Society B|volume=370|issue=1663|page=20140063|pmc=4305164|pmid=25602067|doi=10.1098/rstb.2014.0063}}</ref>

[[File:Resti di australopithecus afarensis detto selam, di tre anni circa, da dikika (afar), 3,3 milioni di anni fa.jpg|thumb|upright=1.5|[[DIK-1-1]] skeleton; notice the diverging left big toe bone]]
The [[heel bone]] of ''A. afarensis'' adults and modern humans have the same adaptations for bipedality, indicating a developed grade of walking. The big toe is not dextrous as is in non-human apes (it is adducted), which would make walking more energy efficient at the expense of arboreal locomotion, no longer able to grasp onto tree branches with the feet.<ref name=Latimer&Lovejoy1989>{{cite journal | last1=Latimer | first1=B. | last2=Lovejoy | first2=C. O. | title=The calcaneus of ''Australopithecus afarensis'' and its implications for the evolution of bipedality | journal=American Journal of Physical Anthropology |volume=78 |issue=3 |pages=369–386 |year=1989 |doi=10.1002/ajpa.1330780306 |pmid=2929741 }}</ref> However, the foot of the infantile specimen DIK-1-1 indicates some mobility of the big toe, though not to the degree in non-human primates. This would have reduced walking efficiency, but a partially dextrous foot in the juvenile stage may have been important in climbing activities for food or safety, or made it easier for the infant to cling onto and be carried by an adult.<ref>{{cite journal|first1=J. M.|last1=DeSilva|first2=C. M.|last2=Gill|first3=T. C.|last3=Prang|display-authors=et al.|year=2018|title=A nearly complete foot from Dikika, Ethiopia and its implications for the ontogeny and function of ''Australopithecus afarensis''|journal=Science Advances|volume=4|issue=7|page=eaar7723|doi=10.1126/sciadv.aar7723|pmid=29978043|pmc=6031372|bibcode=2018SciA....4.7723D }}</ref>