Flo’s Little Brain - The Fossil Chronicles - page 113

Figure 18. The virtual endocast of LB1 from the (A) right side, (B) back,
(C) front, and (D) top. Arrows 1-7 represent advanced features that are dis-
cussed in the topic: (1) protruding occipital lobe; (2) posteriorly located lunate
sulcus (but see discussion); (3) temporal lobe expanded at back; (4) form
of lateral prefrontal cortex, which lacks an apelike fronto-orbital sulcus;
(5) shape of anterior prefrontal cortex; (6) expanded convolutions at front of
brain; (7) expanded bottom of frontal lobe. Created by Kirk Smith, Mallinck-
rodt Institute of Radiology; reproduced from Falk, Hildebolt, et al., “LB1's
virtual endocast, microcephaly,” 2009.
with a displaced, posteriorly located lunate sulcus (which courses near
the front edge of the visual cortex in apes), recent research by John
Allen, of the University of Southern California, and his colleagues sug-
gests that this might not have been the case . 7 Instead, lunate sulci may
simply have disappeared during hominin evolution as brains enlarged
and their connections became internally reorganized . 8 If so, this is a
radical departure from the notion of a posteriorly displaced lunate sul-