Gracile Vs Robust
Robust
post-orbital restriction (mod. prognathism) sagital crest low lying braincase very large projecting brow ridges projecting face flared cheek bones (zygomatic arch) large jaw, big molars heavy, gritty vegetation diet (herbivores) heavy facial muscles specialized diet - cannot adapt quickly
Gracile
pronounced prognathism no sagittal crest low lying brain case less sexual dimorphism not as flared cheeks (mod. zygomatic arch) -smaller cheek teeth -not as large teeth fruit based diet -lacked heavy vegetation -frucavores generalized diet adapts quickly
Species of Gracile
A. anamensis (4.0 mya) A. afarensiss (3.5 mya) (Lucy) A. africanus (3.0 mya) (Taung Child) A. garhi (2.5 mya) A. sedeba (2.3 mya)
Species of Robust
A. robustus ( 2.5 mya) A. boisei ( 2.5-1.4 mya) A. aethiopicus (2.5mya)