A revision of the Early Palaeogene nummulitids (Foraminifera) from northern Oman, with implications for their classification
J. R. Haynes, A. Racey, J. E. Whittaker, 2010. "A revision of the Early Palaeogene nummulitids (Foraminifera) from northern Oman, with implications for their classification", Micropalaeontology, Sedimentary Environments and Stratigraphy: a Tribute to Dennis Curry (1912–2001), John E. Whittaker, Malcolm B. Hart
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Fifteen nummulitid species are described from the Late Paleocene and Early Eocene of northern Oman. These comprise Operculina (five species), Assilina (one), Planocamerinoides (two), Ranikothalia (one), Nummulitoides (three), Palaeonummulites (one) and Chordoperculi-noides (two). The taxa Nummulitoides margaretae, Chordoperculinoides bermudezi, Palaeonum-mulites thalicus gwynae, Assilina ranikoti and Operculina libyca are recorded from the Middle East for the first time. Operculina canalifera and O. inaequilateralis are reassigned to Nummuli-toides; Operculina jiwani and Assilina dandotica are transferred to Planocamerinoides, and Rani-kothalia sahnii is placed in Chordoperculinoides. Some revisions to the generic classification are proposed, with these simple forms being removed to the Palaeonumulitinae, new subfamily herein, genera with lateral chamberlets being confined to the Nummulitinae, and genera with subdivided equatorial chambers being assigned to the Heterostegininae. Enrollment of the lamina and height of the coil (opening rate) is taken into account, as well as the presence or absence of vertical canals and the thickness of the marginal cord. On these grounds, a new genus, Caudrina (type species C. soldadensis), is formally described to include sub-evolute descendants of involute Chordoperculinoides. Trabeculae and trabecular canals are redefined and the problem of their mis-identification in terms of presence/absence as a criterion in the systematics of the Nummulitidae is discussed.
The biostratigraphical and palaeobiogeographical implications of this early nummulitid fauna are significant. The presence of Chordoperculinoides bermudezi in Oman is considered to be of particular importance, since it has previously been considered to be restricted to the Caribbean faunal province. The occurrence also of Ranikothalia nuttalli kohatica extends the geographical distribution of this taxon, which hitherto was only known from NW Pakistan, while Nummulitoides was previously only recorded with certainty from West Africa, Libya, Pakistan, the Pyrenees and from off western Ireland. Other taxa such as Assilina ranikoti and Palaeonummulites thalicus gwynae, and Operculina libyca, were previously only known from Pakistan and Libya, respectively. The fauna therefore shows a marked mixing of taxa from the Indian Subcontinent, the Mediterranean/North Atlantic and West African regions, as well as including a taxon previously considered endemic to the Caribbean.
Forms with a massive marginal cord such as Chordoperculinoides, Ranikothalia and Nummuli-toides indicate an age close to the Paleocene-Eocene boundary (nannoplankton zones NP8– NP10) with Nummulitoides possibly ranging as high as top NP11. Assilina, Palaeonummulites and Planocamerinoides have a first occurrence in the latest Paleocene (within NP9/P5a). Most of the genera studied first appear in the Late Thanetian (NP8/P4b-c) and were probably derived from a tightly coiled ancestor of Palaeonummulites earlier in the Paleocene. Possible lines of descent between these genera are also discussed.
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Micropalaeontology, Sedimentary Environments and Stratigraphy: a Tribute to Dennis Curry (1912–2001)
Dennis Curry was a remarkable polymath and philanthropist, leading a double-life as one of the UK's most gifted amateur geologists, whilst at the same time being an extremely successful businessman (as Managing Director of Currys Ltd). This Festschrift, authored by friends and specialists from Britain and France, pays tribute to his often seminal research as well as exhibiting the wide range of his geological interest. It contains 12 chapters and covers several differing aspects of micropalaeontology (pteropods, diatoms and especially foraminifera), Strontium Isotope Stratigraphy, Hampshire Basin stratigraphy and palaeogeography, as well as major contributions on English Channel sedimentology and the great faunal turnover affecting mammals at the Eocene-Oligocene boundary. A scientific appreciation of Dennis Curry, ‘the professional amateur’, with recollections of former colleagues at University College, London (where he was Visiting Professor), together with an assessment of the valuable collections he established and donated to The Natural History Museum, are also included. Copiously illustrated, this book is a must for all geologists.