KOOBI FOKA (INCLUDES EAST TUKKANA, ILERET) 143
ER 1590G. LP‘. Paracone and metacone b/l com-
pressed and marginalized; a distinct crest runs between
their apices, delineating fairly large, deep anterior fovea
and larger, deeper posterior fovea. Crown continuously
crested in a ring that incorporates the two cusps.
Enamel quite thickly crenulated.
ER 1590H. RP’. Surface more weathered than G,
but morphologically identical.
ER 15901. LP2. Slightly smaller and with less
complex wrinkling than J, but quite similar.ER 1590J. RP2. Very deeply, thickly crenulated
enamel. Protocone and paracone broadly separated
and apices peripheral. Thick preprotocrista runs from
protocone to side of paracone. Thick postcingulum
from side of metacone to base of hypocone encircles a
fairly wide basin.
ER 159015. RM’. Very weathered. Much smaller
and more square than ER 1590M. Enamel was much
less crenulated. Precingulum ran from small parastyle
and partially lingually around base of protocone.
Paraconule present rather than preprotocrista and
there is either a short postprotocrista or a subdivided
metaconule. Postcingulum arcs gently between apices
of metacone and hypocone, enclosing, internal to it, a
moderately wide, narrow fovea.
ER 1590M. LM’ crown. Surface enamel deeply and
thickly crenulated. Beaded cingulum around lingual side
of large protocone extends buccally beyond midline of
tooth. Preprotocrista stout; courses lingually around
compressed paracone. Short postprotocrista goes to
metacone. Thick postcingulum arcs out gently from
apex of metacone to join large, d/l bulbous hypocone.
Deep basin courses internal to postcingulum and
parallel with it. Apices of buccal cusps more marginally
placed than lingual ones (lingual side has longer slope).
KNM-ER 1801. Very weathered L jaw corpus with
alveoli for I1 and 2, roots of C, P1, and M2, and very
severely eroded crowns of P2, Ml, and M3. P1 was
small, apparently single rooted; did not articulate with
distolingual corner of C. Appears there was a
continuous curve from back of tooth row to symphysis.
Jaw quite gracile, deep but quite narrow from side to
side. P2 was not long m/d but was broad b/l. P1 was
probably much smaller and morphologically different
from P2. M1-M3 were subrectangular and slightly
longer m/d than wide b/l. Not much (if any) posterior
molar increase in size.
KNM-ER 3733. Fairly complete cranium with most
of orbits and lower face preserved; orbital floor, medial
wall, and most of nasal fossa missing. Matrix obscures
roof and back of orbit. Neurocranium extensively
cracked but mostly undistorted; postorbital region
possibly distorted significantly on the L; most of
basicranial detail missing.
In profile, cranium moderately tall and long; face
somewhat flat and fairly vertical. In profile, the relatively
tall, backwardly curving frontal rises moderately steeply
from well behind a fairly long postglabellar sulcus.
Supraorbital margins project superiorly rather than an-
teriorly, and create an anterior wall to the sulcus behind.
Skull reaches maximum height at the bulging prebreg-
matic region, behind which the somewhat steeply
downwardly sloping profile is very long. Neurocranium
is distended posteriorly primarily by a bulbous “external
occipital protuberance” incorporated into a low,
mounded, horizontal “keel.” Posterior part of braincase
seems curiously compressed compared to the more ele-
vated anterior portion. Long, almost horizontal nuchal
plane turns in from its somewhat rounded juncture with
occipital plane. From above, postorbital constriction is
fairly marked and the toral-glabellar complex is fairly
straight across the middle (with slight depression due to
damage), retreating only laterally. Neurocranium is
widest across supramastoid regions. From front, neuro-
cranium is not appreciably narrower than superior or-
bital region. Face broadens out more noticeably toward
inferior extents of zygomas. From behind, the relatively
tall and straight side walls of braincase tilt gently in
from laterally undistended supramastoid regions. High
up, they curve fairly strongly and shallowly in toward
the midline, which is almost flat across.
A distinct, keel-like prebregmatic bulge appears to
have been confined to frontal bone. Region of bregma
itself was not elevated; no sign of elevation posteriorly
along sagittal suture or laterally along coronal suture.
Posttoral sulcus delineated bilaterally by steeply rising
frontal behind and by upward-sloping supraorbital
tori in front. Tori arched over orbits and separated by
a slight depression in glabellar region. Depression de-
fined on either side by a distinct medial margin to
each torus. Tori are quite thin, rounded anteriorly, and
form distinct angle with orbital roofs. Allowing for a
medially placed wide, shallow notch inferiorly on each
supraorbital margin, tori uniformly thick from side to
side. Notches are not restricted to inferior margins of
tori. Viewed from above, notches also appear as
distinct concavities in the frontal profile. Tori project