OLDUVAI GORGE 201
grooved internal surfaces. Apices of protoconid and
metaconid lie essentially opposite each other; base of
latter somewhat longer m/d. Apex of hypoconid lies
mesial to slightly smaller entoconid. Hypoconulid
very small; lies buccal to midline, but not as far
buccally as hypoconid. Paraconid shelf between bases
of protoconid and metaconid slightly grooved,
moderately thick. Hypocristid between hypoconulid
and entoconid much more extensive, shelf-like. Slight
traces of cingulid around protoconid give faint hint of
protostylid. On lingual side is a faint hint of
metastylid. Buccal cusps even more internally placed
than internally placed lingual cusps, giving distinct
slope to buccal side of crown and creating long,
narrow talonid basin.
OH 9 Morph
OH 9. Adult. Partial calvaria missing much of vault
roof and area around foramen magnum. Reconstructed
from numerous fragments, with extensive plaster
restoration, especially superiorly.
Very thick-boned skull, with thick inner and outer
tables as well as an expansive diploe. In side view,
frontal is somewhat domed and rises fairly steeply from
fairly far behind anteriorly projecting supraorbital tori.
Posttoral plane long; curves gently up into frontal rise.
Roof of vault missing; in profile was almost certainly
quite rounded, descending at rear into a somewhat flat
occipital plane, which forms an obtuse angle with the
steep, forwardly angled nuchal plane. Viewed from
above, glabella strongly indented; each supraorbital
torus slopes gently back toward sides. As seen on the L,
postorbital constriction marked (but not extremely so).
Seen from behind, cranium very wide across mastoid
processes; preserved L side angles gently inward as it
rises, curving medially high above porion.
Supraorbital surfaces massive, being both tall s/i
and forwardly projecting. Large tori are separated by a
vertical indentation at glabella; each torus curves su-
perolaterally out and up from frontonasal suture. Tori
thickest toward midline, thinning somewhat lateral to
quite medially placed supraorbital notches. From
these notches laterally, tori are uniformly thick.
Orbital roofs somewhat concave superiorly; flow
smoothly onto supraorbital surfaces. Interorbital re-
gion quite broad. Nasal bones probably extended only
slightly higher than frontal processes of maxillae,
which they slightly overlap. Nasal bones broken ca.
1.5 cm below nasion. In profile, preserved nasals quitestrongly inclined posteriorly; show no firm evidence
of any anterior flexion (implying at least a rather flat
nasal region). On the L, posterior lacrimal crest is pre-
served; does not curve around to close off top of
lacrimal fossa. Orbital cones were long, deep. As seen
on the L, frontal lobes extended long way over orbital
cone, but terminated far from its front, at base of
(external) frontal rise.
As seen on the L, temporal line distinct but quite
low at sides of supraorbital tori. As line curves onto
posttoral plane, it begins to form a marked border
between the somewhat bulging lateral vault wall be-
low and the lower-lying surface medial to it. (This is
not a ridge along a uniform surface, but a demarcation
between two distinct surfaces.) Temporal line arcs
quite far superiorly, but stays on side of skull. Posteri-
orly, temporal line descends quite steeply and a bit
anteriorly, to bifurcate slightly just above parietal
notch into two low lines. One line descends to poste-
rior portion of bulky mastoid process; the other turns
forward to flow into the very poorly developed
supramastoid-suprameatal “crest.” On the L, edge
of squamosal suture damaged; possible that anterior
squamosal suture angled in to meet deeply concave
greater wing of sphenoid (thereby creating anterior
and posterior temporal fossae). Impossible to know
whether temporal and infratemporal fossae were de-
lineated. Squamosal itself was apparently very long,
low, poorly arced. Parietal notch shallow; essentially
no parietomastoid suture behind. Posterior root of
zygomatic arch better preserved on the R, it is angled
down quite strongly, and appears to have been quite
shelf-like and laterally projecting. On both sides,
auditory meatus tall s/i, narrow, ovoid. Bone of tall,
rather vertical tubular ectotympanic moderately thick
anteriorly, thicker inferiorly. As seen on the L, tubular
ectotympanic did not extend laterally to side of vault;
tube forms an angle with the thin, anteriorly directed
body of petrosal. Tube closely appressed to anterior
face of mastoid process on both sides.
Mastoid processes broken at bases (projection
undeterminable). On both sides, mastoid bases in-
vaded by quite large air cells and have broad, flat pos-
terolateral surfaces that are delineated medially by
relatively well-developed digastric fossae. R digastric
fossa more deeply incised than the L; fossae do not
extend posteriorly beyond immediate area of mastoid
processes. In front of fossae, mastoid notches appear
to have been very thin, shallow. On the L, a low crest
parallels digastric fossa well lateral to occipitomastoid