Orrorin tugenensis (6 million years ago)*
*Because fossil evidence for Orrorin tugenensis is
scant, a range of dates for when this species lived is not available.
If Orrorin tugenensis is truly a hominid as its
discoverers describe it, the species is by far the oldest-known member of
the family to which humans belong. In fact, at 6 million years old, O.
tugenensis lived near the time when genetic analyses suggest our oldest
hominid ancestor split from the oldest ancestor of the great apes. This
means that there's a chance O. tugenensis could be the proverbial
"missing link" -- or at least one of them.
Certain features, like the teeth
of O. tugenensis, suggest this species could even be more closely
related to Homo sapiens than the many Australopithecus species
it predates. Like our molars, the molars of O. tugenensis were small
compared to any of the australopithecine teeth. Their teeth also had very
thick enamel like ours.
Grooves in the femurs of O. tugenensis,
presumably points where muscles and ligaments attached, suggest that the
species was bipedal. Unfortunately, much about this species, including the
suggested close relationship between it and Homo sapiens, is extremely
speculative and hotly contested.
-> Go to Ardipithecus ramidus