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there were still significant gaps in the faunal record. He further concluded that times
of step-function change in climate and habitat coincided with changes in the hominid
record, as well as with the emergence of
Homo
at around 1.8 Ma, reviewed in the
following chapter (
Chapter 17
).
In contrast to the coarse resolution faunal analysis of deMenocal (
2004
), Macken
et al. (
2012
) were able to provide a much finer resolution analysis for the Late
Pleistocene vertebrate fossils preserved in Victoria Fossil Cave at Naracoorte in semi-
arid South Australia. They found that although certain species reacted to changes
from warm moist to cooler drier regional climatic conditions in much the same way
as they had in the past, others showed a more complex response that was vari-
able and individual through time. They concluded that large fossil samples were
needed in order to demonstrate how particular species had responded to past climatic
changes.
Ambrose et al. (
2007a
) provide a comprehensive analysis of the late Miocene
fossil fauna at the site of Lemudong'o in semi-arid southern Kenya. They were able
to demonstrate changes in habitat at a lakeshore site within a mosaic of riparian
forests, open woodlands and wooded grasslands. At another site, they were also able
to show that an accumulation of carcasses demonstrated significant carnivore damage
on the bones, probably caused by several avian and small mammalian carnivores. As
a prelude to the analysis of the fossil fauna, Ambrose et al. (
2003
;
2007b
) carried out
a thorough study of the geology, geochemistry and stratigraphy of the Lemudong'o
Formation within which the fossils were found, and dated certain widespread tephra
marker beds. Such studies are a vital prerequisite to the analysis of any fossil vertebrate
assemblage, because they can show whether disturbance by running water, mass
movement or tectonic activity needs to be taken into account.
An earlier study of Miocene habitats in East Africa suggested that the progressive
fragmentation of a relatively homogeneous lowland tropical rainforest as a result of
rifting and climatic change led to dispersal out of the forest by some species, extinction
of others and retreat to the forest remnants by others (Malone,
1987
). The dispersal
of Miocene hominoids (see
Chapter 17
) was suggested to be one such response to
habitat change, as was the emergence of hominid bipedalism.
16.4 Invertebrate fossils
16.4.1 Marine foraminifera
Foraminifera are single-celled and mostly marine planktonic animals with a mod-
erately resistant shell of calcium carbonate. Based on the first and last appearances
of particular species of foraminifera, marine geologists have been able to provide a
detailed time scale for the entire Cenozoic and to identify global and regional warming
and cooling events (Zachos et al.,
2001
; McGowran et al.,
2004
;McGowran,
2005
).
Figure 3.4
in
Chapter 3
shows some of the major global environmental changes
