H A 1) A K 89
and back, with drop (stepping down) from posterior
pole to floor of nasal cavity. More laterally, floor of
nasal cavity is essentially continuous, descending quite
smoothly from front to back. Posterior to incisive fos-
sae, on both sides, lateral wall of nasal cavity appears
to curve in quite strongly, level with a thick strut that
runs internally across floor of capacious maxillary
sinus. Base of vomer partially preserved and fades out
anteriorly at orifice of incisive fossa.
Nasoalveolar clivus relatively long and flat across,
and very slightly sunken below lateral nasal margins.
In profile, clivus somewhat prognathic; it curves down
slightly, coincident with the curvature of long anterior
tooth roots. No “pillar” above C roots. On R, bone
swells over P1 root. Anterior root of zygomatic arch
pervaded by maxillary sinus that swells out broadly,
high above region of M1 and 2.
Palate not broken perfectly down midline so
that, anteriorly, L portion retains part of alveolar
wall of RI1 and posteriorly part of R palate, and also
the cross-section of R palate, which seems to thin
markedly posteriorly from the taller section that is
overridden by the nasoalveolar clivus. On L, how-
ever, thinning much less pronounced. On both
sides, nasoalveolar clivus appears to be relatively
uniformly thick. Clivus separated from palate below
by modest but well-defined incisive canal. Canal
continues out onto palate as groove that runs to just
behind I1 region. When both halves of palate are
approximated, incisive foramen is moderate in size
and fans out anteriorly in a long, broad gutter that
runs to behind Is. Palate itself is relatively narrow
and very shallow anteriorly, deepening modestly and
smoothly toward back. Walls of palate are somewhat
outwardly sloping. Cheektooth rows relatively
elongate, fairly close together, slightly bowed, and
converge slightly posteriorly.
Maxillary sinuses capacious, divided into anterior
and larger posterior portions by a thickened strut of
bone that runs laterally and slightly backward. As bet-
ter preserved on R, sinus did not extend fully up wall
of nasal aperture, at least anteriorly, where a horizon-
tal ledge of bone truncates it. Superior surface of bony
ledge is concave (as expected if it were floor of sinus
above). Behind ledge, maxillary sinus continues supe-
riorly to flow into superior surface of the ledge. On
the R and more faintly on the L is a groove for greater
palatine nerve and artery.
I1 alveoli only modestly larger than I~s, although
slightly broader m/d. Preserved L12 greatly worn but
would have been quite flared laterally. Lingually is a
well-developed tubercle, from which extend thick
margocristae defined internally by deep creases. Bro-
ken LC preserves very long, stout root; crown would
have been relatively short, broadly triangular in pro-
file, with longer distal than mesial slope. Internally, is
a very mesially placed vertical pillar that ran from
apex of tooth to its base, which is not very swollen.
Small, moderately deep fovea lies mesial to pillar, and
is bounded mesially by thick margocrista. Distal to
pillar was a very broad but shallow fovea bounded by a
margocrista. As judged by R side, P1 somewhat b/l
broader than P2. P1 slightly longer m/d buccally than
lingually, and P2 the reverse. P1 buccal surface some-
what swollen, more so than on P2; parastylar region
also much more strongly developed. On P1 and 2,
paracone centrally placed; protocone lies medially and
somewhat lower. On P2, d/l portion of tooth more
prominent than in P1; although worn, it seems there
was horizontal crease on midline between bases of
protocone and paracone, with very small foveae at
each end of crease. At least on P2, there is evidence
for a stout but short postprotocrista running to meta-
cone base.
Best preserved molars are RM1 and LM2. Ml
not notably large compared to Ps, but of similar b/l
width. M2 somewhat larger in all dimensions than
M1. In both Ms, buccal roots separate very close to
crown; very worn protocone was huge, its apex
probably quite centrally shifted. Hypocone very large
and swells out crown, especially distally. Very stout
postcingulum runs from hypocone to lateral side of
metacone; metacone noticeably smaller than paracone.
On Ml, but much more so in M2, mesiobuccal
portion of crown is emphasized.REFERENCESKimbel, W. et al. 1997. Systematic assessment of a maxilla
of Homo from Hadar, Ethiopia. Am. J. Phys. Anthropol.Walter, R. 1989. Applications and limitations of fission-
track geochronology to quaternary tephras. Quat Int. 1:103: 235-262.35-46.Repository
National Museum of Ethiopia, PO Box 76, Addis Ababa,
Ethiopia.