(^120) MALCOLM B. HART, MELISSA J. OXFORD & WENDY HUDSON
Fig. 5. Distribution of planktonic foraminifera in the Oxfordian.
described by Fuchs (1967) and which have been
seen by the senior author in The Natural History
Museum. This species appears to be a disaster or
opportunist taxon, according to the definition of
Harries et al. (1996). These more inflated forms
of O. quadrilobata are found in the UK,
Germany and France (Hylton 2000), while the
associated fauna of Praegubkinella spp. is only
known from Switzerland (Wernli 1995) at the
present time.
Our more inflated specimens of O. quadrilo-
bata are probably still benthonic forms as the
apertural side remains relatively flat. It is clear,
however, that chamber inflation has occurred
and it is impossible to deny the possibility that,
in mature specimens, some degree of 'floating'
Fig. 6. Distribution of planktonic foraminifera in the Valanginian.