LAETOLI (NGALOBA) 165
to this, profile curves smoothly down to region of ex-
ternal occipital protuberance. More inferiorly, fairly
vertical nuchal plane undercuts occipital plane. From
above, sides of vault taper steadily from widest point
(which lies behind mastoid region) anteriorly to a very
shallow postorbital constriction. Seen from behind,
braincase forms a smoothly rounded curve up and
around between mastoid processes (i.e., quite “en
bombe”) that is only mildly broken by swelling of tem-
poral lines. As best followed on the R, low temporal
lines come right off the lateral portions of the supraor-
bital tori, stay low on parietals, and curve smoothly
down to mastoid region. On L parietal (near lambdoid
suture) is small circular depression (probably of patho-
logical origin). Supraorbital margins are relatively thick
s/i, tapering slightly laterally. Shallow grooves course
on both sides laterally up and away from shallow supra-
orbital notches. These grooves delineate a broad glabel-
lar butterfly undercut by a thick lateral plate. This divi-
sion is also visible from above, emphasizing the
essentially bipartite nature of the brow despite thick
lateral margins. Also seen from above, the region of
glabella shallowly indented with the brows angling
gently back from it. Lateral to the supraorbital notch,
the bone angles smoothly from orbital roof to anterior
surface of supraorbital torus. Supraorbital foramen lies
lateral to each supraorbital notch. Interorbital region is
quite broad; preserved down to just below level of na-
sion. R and L frontal sinuses well separated from one
another; do not expand laterally beyond supraorbital
notch or posteriorly beyond supraorbital thickening.
Large central chamber, confined to region below and
behind glabella, lies between lateral sinus chambers.
Frontonasal suture was fairly high up and probably ran
quite straight across. Internally, frontal lobes extended
well over orbital cones and were separated by a long,
moderately thick, relatively low frontal crest.
Temporal bones show smooth transition from
anterior squamosal into temporal fossa. Temporal and
infratemporal fossae separated by an angle in the
alisphenoid. Squamous portion of temporal was quite
high and arced, terminating posteriorly in a vertical,
right-angled parietal notch. Parietomastoid suture
short; angles slightly upward. Articular fossae broad
mil, bounded anteriorly by a steep wall that does not
form an eminence (profile in front is flat). Fossae deep-
est anteriorly; posterior surface formed by the back-
wardly angling anterior surface of tubular ectotympanic
(no postglenoid process). As seen on the L, fossa not
closed off medially. On both sides, tympanic plate quite
thickened, appressed to a distinct, slightly anteriorly
pointing, not very projecting, m/l narrow mastoid
process. Vaginal process rises as a low peak around what
would have been a relatively thick, medially placed sty-
loid process; as seen on the R, vaginal process continues
right to meatus of short ectotympanic tube as a low
crest that remains well separated from mastoid process.
Stylomastoid foramina relatively large; lie well behind
and lateral to regions of styloid processes. Carotid
foramina lie quite medial to styloid processes; probably
pointed down. Foramen spinosum relatively large; is
contained within sphenoid and well separated from
quite small, round foramen ovale.
Posterior root of zygomatic arch takes origin ante-
rior to and slightly above auditory meatus; is confluent
with low suprameatal crest that expands into an anteri-
orly placed supramastoid swelling (not crest). Beginning
medial to mastoid process and running behind it is the
mastoid notch, which terminates in a distinct &gastric
fossa. Notch and fossa deeper and broader on R than on
L. Region of occipitomastoid suture (on R) not as down-
wardly projecting as mastoid process, and bears no crest.
Lambdoid suture rises steeply from asterion and
appears to curve relatively smoothly across lambda.
Occipital plane appears “bunned” (because nuchal
plane undercuts it strongly), but there is no clearly de-
fined occipital torus. Nuchal markings very faint. No
well-defined external occipital protuberance. External
occipital crest low, broad, and barely distinguishable
from surrounding bone.
Internally, on the L and especially the R, is a well-
defined, dome-shaped arcuate eminence. On the L
(region is broken on R) is a trace of a thin superior
petrous sinus running along most of length of pet-
rosal. On both sides, subarcuate fossa not entirely
filled in. Superior sagittal sinus faintly preserved in
places. R transverse sinus diverges above level of thick,
swollen internal occipital protuberance, from which
the more clearly defined horizontal L transverse sinus
emerges. L occipital lobe larger, more deeply im-
pressed than R reverse for cerebellar lobes. On both
sides, a broad sigmoid sinus arcs behind petrosal; on
the L, this continues forward and inferiorly as well.
On the L, a portion of sphenoid sinus preserved; it is
not expansive posteriorly.Maxilla
Includes frontal process and anterior root of zygo-
matic arch on the L; neither is penetrated deeply by