The upper Katian (Ordovician) bryozoans from the Eastern Iberian Chain (NE Spain)

Abstract

The upper Katian (Upper Ordovician) bryozoans from the Iberian Chains (NE Spain) are described. Twenty-three species are identified, five of them are new, seven were already identified in other paleocontinents and Mediterranean localities, four are provisionally referred to other known species, and seven are undetermined species. All of them belong to 22 genera assigned to 14 families, and to one incertae sedis genera. The five Stenolaemata orders (Cryptostomata, Cyclostomata, Cystoporata, Fenestrata and Trepostomata) are represented here, Trepostomata and Cryptostomata being the most abundant and diverse. The trepostome family Halloporidae is the one with the highest diversity, with 4 genera and 5 species described here. The five new species are the cryptostomes <i>Pseudostictoporella iberiensis </i>sp. nov., characterized by the presence of superior hemisepta in the autozooecia, and <i>Prophyllodictya javieri </i>sp. nov., also characterized by the presence of superior hemisepta in the autozooecia and by its small exilazooecia; the cystoporate <i>Ceramoporella inclinata </i>sp. nov., whose main diagnostic character is the constant autozooecial inclination; and the trepostomates <i>Dybowskites ernsti </i>sp. nov., easily recognizable by its large autozooecial and mesozooecial apertures, as well as by its large acanthostyles and <i>Trematopora acanthostylita </i>sp. nov., mainly characterized by the absence of diaphragms in its mesozooecia and numerous, large acanthostyle

New bryozoans from the Upper Ordovician of Morocco and their place in the temperate-to-cool water Mediterranean Province

“…-The arrangement of autozooecial apertures in longitudinal rows separated by prominent ridges; the presence of the central axis with autozooecial rows around it; the shape of autozooecial cross-section both in endozone and exozone; as well as the absence of autozooecial diaphragms and mesozooecia have allowed us to assign this material to Ulrichostylus. These specimens fit well with Ulrichostylus radiatus as was described by Conti (1990) in the Upper Ordovician type material from Sardinia (Italy), by Ernst & Key (2007) in the Upper Ordovician from the Montagne Noire (France) and by Jiménez-Sánchez (2009) in the Upper Ordovician of the Iberian Chains (Spain). The Moroccan material shares with them the absence of autozooecial diaphragms and acanthostyles, as well as a similar number of autozooecial rows and similar autozooecial diameter; consequently these specimens are included in U. radiatus.…”

“…However, it is one area in the whole of North Africa, close to Erfoud in the eastern Anti-Atlas, which displays an extraordinary bryozoan diversity. The on-going studies on bryozoan associations of the late Katian Khabt-el-Hajar Formation have shown a diversity that parallels those of the Iberian Chains (Jiménez- Sánchez 2009Sánchez , 2010) and the Sardinian occurrences (Conti 1990), and it is only surpassed in the Mediterranean Province by the occurrences studied in the Montagne Noire (Ernst & Key 2007).…”

Palaeogeographical patterns in Late Ordovician bryozoan morphology as proxies for temperature

“…Carbonate skeletons of cheilostome bryozoans living in warm waters comprise calcite, aragonite or are bimineralic (with calcite overlain by aragonite), and in those employing calcite the percentage of Mg is often high (Smith et al 2006, Taylor et al 2009). On the other hand, in cold-water, cheilostome species with aragonitic and bimineralic skeletons are rare and the Mg content in the calcite is typically lower (Kuklinski & Taylor 2008, 2009Loxton et al 2012). These mineralogical and chemical differences in bryozoan skeletons have been linked to environmental factors -mainly temperature -because they have also been found to occur within congeneric species that inhabit different temperature habitats.…”

The oldest known bryozoan: Prophyllodictya (Cryptostomata) from the lower Tremadocian (Lower Ordovician) of Liujiachang, south‐western Hubei, central China

“…nov., is here reported from the lowest member of the Nantzinkuan Formation (lower Tremadocian), several millions of years older than the previously oldest known bryozoans from the Fenhsiang Formation, also from central China. Apart from central China, it is worth noting that Prophyllodictya is known from the middle Dapingian Stage of Estonia onwards (Gorjunova and Lavrentjeva , ) and the Katian Stage of Spain (Jiménez‐Sánchez ; Fig. ), indicating dispersion of Prophyllodictya during the Ordovician.…”

“…Taken at face value, the fossil record points to the South China basin as the centre of origin of bryozoans, where the most ancient bryozoans of the Cryptostomata ( Prophyllodictya from the Nantzinkuan Formation) and Trepostomata ( Orbiramus and Nekhorosheviella from the Fenhsiang Formation) first appeared. Bryozoans subsequently invaded the Siberian and Baltoscandian basins during the late Tremadocian and migrated into the North American and Avalonian basins as late as the Dapingian Stage (Middle Ordovician; Koromyslova ) and then into Mediterranean in the Late Ordovician (Katian; Jiménez‐Sánchez ). The dispersion of Prophyllodictya in space and time might also indicate a temperature increase through the Early to Late Ordovician (Jiménez‐Sánchez and Villas ).…”