New bryozoans from the Upper Ordovician of Morocco and their place in the temperate-to-cool water Mediterranean Province.
Résumé
A new study of the Upper Ordovician bryozoans belonging to the families Aisenvergiidae, Amplexoporidae,
Arthrostylidae, Enalloporidae, Halloporidae, Heterotrypidae, Mesotrypidae, Ptilodictyidae, Rhinidictyidae and
Trematoporidae from the eastern Anti-Atlas of Morocco is presented here. These bryozoans come from the calcarenitic
levels of the Khabt-el-Hajar Formation, upper Katian, where for the first time the orders Fenestrata and Cryptostomata
are described in this formation. This fauna inhabited an upper offshore environment and represent high-energy deposits,
typical of a shore face environment, as well as storm-induced deposits. A total of 15 species included in 13 genera, 10 of
them only identified in the calcarenitic levels of the Khabt-el-Hajar Formation, and two incertae sedis taxa are described.
A new species, Trematopora vesiculata, is defined. An update of the Upper Ordovician bryozoan presence/absence database,
including the 22 genera described in total in the Khabt-el-Hajar Formation, has been carried out. The augmented
database has been analysed with two multivariate statistical techniques: detrended correspondence analysis (DCA) and
principal coordinate analysis (PCO), in order to assess the palaeogeographic affinity of this fauna, and the results show
that Moroccan bryozoans, in spite of belonging to the fauna developed in the highest latitudes during the upper Katian,
have a clear Mediterranean affinity.