Re: Did Lucy have human-like hands and feet?

Susan S. Chin (susansf@netcom.com)
Sat, 10 Aug 1996 03:37:15 GMT

Holly Reeser (reeser@flmnh.ufl.edu) wrote:
: Steve Geller wrote:
: >
: > "Lucy" may be offered as a "missing link", but it's not all that
: > certain. Australopithecines in general are most likely cousins of the
: > human line -- perhaps one small group of them are our ancestors, not
: > neccessarily the Lucy tribe.
: >
: > What Lusy tells us is that hominids begain walking upright as early as
: > 3.5 million years ago. The same story is told by the Laetoli
: > footprints. So upright walking was not a major selector
: > for human evolution.
: >
: > --
: > Steve Geller
: You haev omitted a very important recent find by Maeve Leakey -
: Australopithecus anamensis. Securely dated at 4.4 mya it shows

I hadn't heard that anamensis is now at 4.4mya, what's your source for
the new date? If anamensis is 4.4mya, then it would be contemporaneous
with Ardipithecus ramidus, which sets up an interesting situation. My
information (from Leakey, et al. Nature 376, August 17, 1995) has
anamensis at 3.9-4.2mya.

: nonambiguous evidence of bipedality in its tibia. The tibia's head is
: aligned directly over the shaft indicating bideped stance and locomotion.

Yes, and other features of the tibial condyles (articular surface with
femur) also indicates bipedalism: medial and lateral condyles concave,
and fairly equal in size, and the overall shape of the proximal surface
anteriorly is rectangular and elongated anteroposteriorly. The shaft is
also noted to be very straight, though the middle shaft was not
recovered. Also, the distal articular surface of the tibia, which
articulates with the foot bones, faces directly inferiorly.

: Although I agree that just becaue something is bipedal does not assure
: its place in the direct ancestry for H.S.S's. And because of 50
: morphological characters in common between A.africanus and H. habilis
: and not between H. habilis and A. afarensis ..I find it hard to see A.
: afarensis as being ancestral in any way to H.S.S. They are most likely
: directly ancestral to the robust lineages and possess many more
: synapomorphies (shared-derived characters) with the robusts.

For the sake of discussion, what are some of these characters which
africanus and habilis share, which afarensis does not?

Susan

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                                             susansf@netcom.com