Geoscience Reference
In-Depth Information
fables, would have been more interested in consuming warm hearts. So far, though,
no one has noted any trace fossil evidence of storks preying on or scavenging
H. floresiensis
, such as beak marks on bones or coprolites holding the remains
of furry feet. More likely menu items for these storks would have been rodents of
unusual size, such as the Flores giant rat (
Papagomys armandvillei
), which was
more than double the length of the biggest urban rats.
However, Pleistocene trace fossils from South Africa do show evidence of a
bird attacking a small hominin. These consist of holes in the skull of the “Taung
child,”whichbelongedtoajuvenile
Australopithecus africanus
.Atfirstinterpreted
as leopard toothmarks, these holes are now regarded as beak and talon marks from
an eagle, neatly matching traces left on modern monkey bones by African crowned
eagles (
Stephanoaetus coronatus
). Some paleoanthropologists even speculate that
frequenteagleattackswouldhaveselectedformorecooperativebehaviorandlarger
body size in hominins, thus deterring these predators and contributing to greater
stature.
As one might have figured out by now, islands do funny things with the evol-
ution of birds, especially related to body size. Paleontologists and biologists have
noted two seemingly opposite trends: smaller animals that colonize islands tend to
get larger over time, whereas larger animals get smaller. Both can be summarized
as the “island rule,” although this can be split into “island gigantism” and “island
dwarfism,” respectively. Given the right ecological conditions and enough time,
natural selection on an island can drive an animal's lineage down either path. For
instance,ifwhatwewouldconsidertodayas“normal”-sizedswans,ducks,pigeons,
or owls had flown to islands during the Pleistocene, were genetically isolated from
others of their species over several hundred generations, had no natural predators,
andplenty toeat, thentheir descendants might havebecome muchlarger.However,
with great size came great responsibility: to gravity, that is. Part of this natural se-
lection toward gigantism in birds would have reduced any energetically expensive
