Title: New Paleocene Sepiid Coleoids (Cephalopoda) from Egypt: Evolutionary Significance and Origin of the Sepiid 'Rostrum'
Authors: Kostak, Martin ×
Jagt, John W. M.
Speijer, Robert
Stassen, Peter
Steurbaut, Etienne #
Issue Date: Dec-2013
Publisher: Public Library of Sciene
Series Title: PLoS One vol:8 issue:11
Article number: e81180
Abstract: New coleoid cephalopods, assignable to the order Sepiida, are recorded from the Selandian/Thanetian boundary
interval (Middle to Upper Paleocene transition, c. 59.2 Ma) along the southeastern margin (Toshka Lakes) of the
Western Desert in Egypt. The two genera recognised, Aegyptosaepia n. gen. and ?Anomalosaepia Weaver and
Ciampaglio, are placed in the families Belosaepiidae and ?Anomalosaepiidae, respectively. They constitute the
oldest record to date of sepiids with a ‘rostrum-like’ prong. In addition, a third, generically and specifically
indeterminate coleoid is represented by a single rostrum-like find. The taxonomic assignment of the material is based
on apical parts (as preserved), i.e., guard, apical prong (or ‘rostrum-like’ structure), phragmocone and (remains of)
protoconch, plus shell mineralogy. We here confirm the shell of early sepiids to have been bimineralic, i.e., composed
of both calcite and aragonite. Aegyptosaepia lugeri n. gen., n. sp. reveals some similarities to later species of
Belosaepia, in particular the possession of a distinct prong. General features of the phragmocone and protoconch of
the new form are similar to both Belocurta (Middle Danian [Lower Paleocene]) and Belosaepia (Eocene). However,
breviconic coiling and the presence of a longer ventral conotheca indicate closer ties with late Maastrichtian–Middle
Danian Ceratisepia. In this respect, Aegyptosaepia n. gen. constitutes a link between Ceratisepia and the Eocene
Belosaepia. The occurrence of the new genus near the Selandian/Thanetian boundary suggests an earlier origin of
belosaepiids, during the early to Middle Paleocene. These earliest known belosaepiids may have originated in the
Tethyan Realm. From northeast Africa, they subsequently spread to western India, the Arabian Plate and, probably
via the Mediterranean region, to Europe and North America.
ISSN: 1932-6203
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Division of Geology
× corresponding author
# (joint) last author

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