Apes first appeared in Africa during the Early Miocene 23 – 16 million years ago (mya). The regions of Ethiopia, Kenya, Uganda, and Nambia are littered with the earliest of their remains. The drastic climatic distribution of dry and wet seasons and geographical partitions that dominate east Africa today had not yet taken place and the landscape was probably a mixture of forests and moist woodlands (Stanford, et al.). Environmental changes were drying the landscape, transforming it into open-vegetated woodlands and grasslands. Evidence of land connection between Eurasia and Africa first appeared approximately 17mya allowing early hominoids their first opportunity to emigrate from Africa. By 11mya hominoids were well established throughout Eurasia.
Many researchers feel that the Propliopithecids which is best represented by Aegyptopithecus zuexis are ancestral to the extant apes. A. zuexis possessed the 2:1:2:3 dental formula as do the extant apes, but lack their molar pattern and body plan. Proconsul provides us with the first evidence of divergence from the cercopithecoidal bilophodont molar pattern, believed to be useful for shearing fibrous plant material. Dental apes, as they are referred to, possess the derived Y-5 hominoid molar pattern, but lack the postcranial characteristics seen in their extant cousins. Modern apes are broad-chested with posteriorly attaching shoulder girdles, allowing for an increased range of motion and suspensory capabilities.
The earliest evidence of the modern ape body plan is dated to approximately 15mya and credited to Morotopithecus. The postcranial design of apes is well adapted for increased suspensory activities such as arm hanging and brachiating. According to Stanford, et al., “Arm hanging could have been adaptive to suspending a large primate under a tree limb from which ripe fruit was growing. The limb could not support the primate from above but could easily support its weight from beneath.” Short broad pelvis’, short spinal columns, grasping hands and feet, robust jaws, flattened faces with downward facing nostrils, and a lack of a tail are ape signature characters (Burnie and Wilson).
Early Miocene;17-15 MYA
The Loire Valley, Sanson and Lo Grive, France