Evolutionary trends and biostratigraphical application of new Cenomanian alveolinoids (Foraminifera) from the Natih Formation of Oman

2016-11-17T11:03:26Z (GMT) by V. Vicedo A. Piuz
<p>An exhaustive sampling of the Cenomanian deposits corresponding to the Natih Formation in the Oman Mountains has been carried out in several field trips. The larger foraminifera representatives of the superfamily Alveolinoidea Ehrenberg, <a href="#cit0006c" target="_blank">1839</a> found in the collected material have been studied in order to more precisely identify and constrain their stratigraphical distribution. The following new taxa are introduced: Decastroinae subfam. nov., Praealveolininae subfam. nov., <i>Reichelia</i> gen. nov., <i>R. magna</i> sp. nov., <i>Decastoria serrakieli</i> sp. nov., <i>D. oblonga</i> sp. nov., <i>D. miaidinensis</i> sp. nov., <i>Praealveolina arabica</i> sp. nov. and <i>P. acuta</i> sp. nov. Other simpler alveolinoids, such as <i>Simplalveolina</i> gr. <i>simplex</i>, have been found together with these forms. The alveolinoids have been found in four successive assemblages. Assemblage I contains <i>Alveocella wernliana</i>, <i>Myriastyla omanensis</i>, <i>M. grelaudae</i> and <i>Cisalveolina nakharensis</i>; assemblage II contains <i>Decastroia serrakieli</i> sp. nov. and <i>Simplalveolina</i> gr. <i>simplex</i>; assemblage III contains <i>D. razini</i>, <i>D. oblonga</i> sp. nov., <i>Reichelia magna</i> gen. et sp. nov., <i>D. miaidinensis</i> sp. nov. and <i>Simplalveolina</i> gr. <i>simplex</i>; and assemblage IV, which is only found in Wadi Mi'Aidin, contains abundant <i>D. miaidinensis</i> sp. nov., <i>Praealveolina arabica</i> sp. nov. and <i>P. acuta</i> sp. nov. The age attributed to assemblage I is lowermost Middle Cenomanian, the age of assemblages II and III is Middle Cenomanian, and assemblage IV is interpreted as Middle Cenomanian to early Late Cenomanian. From a phylogenetic point of view, alveolinoids diversified and evolved in two successive episodes: a lower maturation cycle, corresponding to assemblage I, and an upper cycle, corresponding to assemblages II to IV. Cenomanian alveolinoids are more abundant and diverse than was previously thought and it seems that they split and evolved in parallel lineages, probably from unknown simple alveolinoids of milioline origin.</p> <p><a href="http://zoobank.org/urn:lsid:zoobank.org:pub:B7A96EE3-BEF7-49E9-A3E0-9FE6094FB0A2" target="_blank">http://zoobank.org/urn:lsid:zoobank.org:pub:B7A96EE3-BEF7-49E9-A3E0-9FE6094FB0A2</a></p>