Ardipithecus Ramidus

<em>Ardipithecus ramidus</em>

Type specimen (ARA-VP-1.129), discovered in 1994 by Tim White.  Photo courtesy of Hefner, Joseph.  Ardi.  January 24, 2017

<em>Ardipithecus ramidus</em>

Aridpithecus ramidus ("Ardi"): a relatively complete skeleton published in 2009 (ARA-VP-6/500)  Photo courtesy of http://ana215fossils.weebly.com/ardipithecus-ramidus.html

 

<em>Ardipithecus ramidus</em>

Artist reconstruction of "Ardi."  Photo courtesy of J.H. Matternes

In 1994, Tim White announced the discovery of a new species based on a juvenile partial mandible.  This was met with a great deal of debate, as juvenile fossils are well known for being morphologically deceptive.  In 2009, the discovery of a large collection of non-juvenile fossils - many of them from a single specimen - validated the initial announcement.  “Ardi,” as this creature has been dubbed, was found with a great deal of other fossil evidence indicative of a heavily forested paleoenvironment.  Astonishingly, it was found with fossilized seeds and wood, as well as several species of non-hominin animals, including monkeys.  This collection paints a vivid picture of heavy woodlands typical of a flood plain.  Ardi has many features that suggest an arboreal lifestyle: long, curved phalanges, a divergent big toe, and a short palm - which points to palm walking rather than the expected knuckle-walking.  This discovery could mean that knuckle-walking is not an ancestral locomotive method, but one that evolved later (and independently) in gorillas and chimps.  Humans appear never to have passed through this long-assumed style of movement.  In contrast to her ape-like arms, Ardi also has less pronounced canines than their predecessors and a more centrally located foramen magnum, which points to bipedalism.  Based on dentition, Ardi appears to have been omnivorous, but did not regularly consume harder substances such as nuts.