Abstract:
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A site in the western flank of Jabal Ja’alan
(Oman Mountains) reveals an exceptional succession across
the Cretaceous–Palaeogene boundary. The sampled interval
comprises a series of carbonates deposited in shallow-water
platform environments and belonging to the Murka Formation,
which lies between the Simsima and Abat formations
of latest Cretaceous and Thanetian age, respectively.
The larger foraminifera recovered from this interval belong
essentially to the group of larger rotaliids (Rotaliidae). Two
new genera and two new species are here described,
Praelockhartia neoakbari gen. et sp. nov. and Rotaliidium
parvum gen. et sp. nov. The former shows a very characteristic
architecture of an umbilicus with strong piles and
two types of umbilical cavities, while the latter has characteristic
dorsal supplementary chamberlets. Other species
such as Rotalia cf. jacobi, Rotorbinella hensoni, Rotospirella
conica and Lockhartia sp. complete the rotaliid assemblage.
The entire assemblage can be considered to be of late
Danian age and to belong to shallow benthic zone SBZ 2.
The larger rotaliids appear to have recovered and diversified
earlier than any other larger benthic foraminifera in
the region after the K–Pg crisis. The rotaliids from the
Murka Formation also appear to be linked to the Lockhartiinae
and to play a special role in improving our understanding
of subsequent diversification in the Lockhartia
Sea. A new subfamily, Praelockhartiinae, is erected to
accommodate all primitive forms that are architecturally
close to lockhartiines.
Key words: Foraminifera, Rotaliidae, Maastrichtian,
Danian, Paleocene. |