[Taxacom] Homo floresiensis phylogeny

John Grehan jgrehan at sciencebuff.org
Wed Nov 12 08:47:28 CST 2008


Some of you may have seen the NOVA program last night outlining the
controversies and evidence over the flores (hobbit) hominid. The
connections implied between humans and australopiths are particularly
interesting, as was the theorized ancestral range between Africa and
Asia. Although it was portrayed in the typical African center of origin
and dispersal model, it is intriguing as to whether all these
connections between humans and orangutans, australopiths and flores,
early Homo in Africa and Asia are all the result of dispersal just from
Africa. Maybe Croizat was right in arguing for an old track between them
across which were continual movements and differentiation without any
particular locality representing the "center of origin". Anyway, below
are some comments and characters listed for the flores material in 2007.
Peter Brown tells me that some are wrong, although he did not specify
which at this time. 

 

John Grehan

 

These some systematics observations made by Jeffrey Schwartz (2007)
regarding some of the enigmatic character affinities shown in the
skeleton from "Defining Hominidae", a chapter in vol 3 Handbook of
Paleoanthropology (Henke and Tattersall eds) under final comments where
he says the combination of morphologies floresiensis would be unexpected
at any time period. He also notes:

 

"...the internal morphologies are odd. The teeth are not necessarily
hominid, the humeral shaft lacks the torque or "twist" characteristic of
large-bodied hominoids (Morwood et al., 2005) and the morphology of the
distal particular region is clearly not hominoid (Schwartz 1986; Morwood
et al, 2005), the tibia is clearly not hominid, the femur is
Orrorin-like, and the partial os coax is somewhat "australopith"-like.
So why is the composite Flores specimen considered a species of Homo
when its affinities to a clade Hominidae are not clear? Largely because
there has been a history of allocating specimens to taxa based more on
their geological age than on their morphology - which in turn, has led
to the general practice of trying to explain away "anomalous"
morphologies in terms of variation. Methodologically, however, before
one even contemplates referring a species to a genus and species, one
should have to defend first why any specimen is a hominid and then a
member of the smaller subclades that subsume that species. But in order
to do so, we must have a working definition of this potential clade that
is open to criticism and revision. In this regard there is still much
work to be done."

 

The character distributions are as follows:

 

*        Moderately globular cranium (some hominids)

*        Somewhat thickened and interiorly (but not superiorly)
protruding but rim like supraorbital margins with no sulcus behind
(australopiths in part and orangutans and their relatives)

*        Tall, ovoid orbits (Pongo, Sivapithecus, some "australopiths")

*        Flat nasal banes (most hominoids, including some "Homo")

*        Forwardly facing and vertical yet superioinferioly short
zygomas (australopiths and orangutans and their relatives)

*        Well-developed mastoid process (some "australopiths" and some
"Homo")

*        Thick frontal with thick diploe (autapomorphic or pathological)

*        No frontal sinus (most primates, including bonobos)

*        Anterior crainial fossa that does not extend fully over orbital
cones (most primates, incuding some "Homo")

*        Clivus that slopes gently away from the dorsum sellae (most
primates, including some "Homo")

*        basion, the bicarotid and biporonic cords in alignment
(juvenile anthropoids, some adults)

*        broad incisive foramen proceeding interiorly as an expanding
grovove (a few "australopiths")

*        marked separation of nsasoalveolar clivus and interiorly think
palate (African apes, some Miocene hominoids, some "australopiths")

*        smooth but narrowly curved mandibular symphyseal region (many
anthropoids)

*        long retromolar space (various "Homo")

*        broadly and smoothly rounded but somewhat truncated gonial
angle (some "Homo")

*        very anterioposteriorly long sigmoid notch (some "Homo")

*        sigmoid notch crest deepest near coronoid process
(autapomorphic)

*        very large cheek teeth and apparently relatively small anterior
teeth (some "australopiths")

*        unusually mesiodistally short upper and lower molars with large
mesial and truncated distal cusps (autapomorphic)

*        relatively long ilium (SK 50)

*        ilium with beaklike anterior superior iliac spine (great apes,
SK50, MLD 7 and 25)

*        poorly defined iliac pillar (australopiths)

*        knoblike anterior inferior iliac spine that lies noticeably
superior to iliac pillar and somewhat back over supracetabular rim
(hominids as discussed in chapter)

*        arcuate line that descends well before reaching region of
acetabulum (some hominids)

*        no ischial spine (most primates)

*        posterior iliac expansion that defines a greater sciatic notch
(hominids as used in chapter)

*        "V" shaped greater sciatic notch (most hominids, but not
Neanderthals)

*        Large femoral head (most primates)

*        Long anterioposteriorly compressed femoral neck (Orrorin,
"australopiths" including BOU-VP-12/1, WT 150000)

*        Well-defined intertrochanteric crest (most primates, but not WT
1500, Orrorin, and most if not all "australopiths"

*        Medially facing lesser trochanter (most primates, not
"australopiths")

*        Weakly developed linea aspera (Orrorin)

*        Femoral "carrying angle" (australopiths" and "Homo")

*        Tibia much shorter than femur (at least apes)

*        Poorly differentiated tibial tubercles (most primates)

*        Medial tibial facet for the femoral condyle lower than the
lateral (at least apes)

*        Convex medial tibial facet (at least apes)

 

 

 

 

 

Dr. John R. Grehan

Director of Science

Buffalo Museum of Science1020 Humboldt Parkway

Buffalo, NY 14211-1193

email: jgrehan at sciencebuff.org

Phone: (716) 896-5200 ext 372

 

Panbiogeography

http://www.sciencebuff.org/biogeography_and_evolutionary_biology.php

Ghost moth research

http://www.sciencebuff.org/systematics_and_evolution_of_hepialdiae.php

Human evolution and the great apes

http://www.sciencebuff.org/human_origin_and_the_great_apes.php

 

 




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