Corals from the Carboniferous of the central Sahara (Algeria): the collection “Marie Legrand-Blain”

Abstract

The collection “Marie Legrand-Blain” contains a diverse fauna of Carboniferous corals from the marine strata of the Algerian Sahara. Among 96 specimens, there are 34 rugose coral taxa and four tabulate coral taxa. Saharaphrentis tirechouminoidense n. gen., n. sp., ?Amplexizaphrentis illizidensis n. sp. and Haplolasma paraarciferum n. sp. are new. The supposed high coral diversity of the Sahara basins is confirmed by the present study. The interspecific and intraspecific variabilities are hardly known, because the number of specimens is limited; commonly a single or few specimens. Thus populations could not be studied and in some cases only an assignment at generic level is possible. Two main coral associations can be distinguished. Undissepimented solitary rugose corals (“zaphrentids”) and michelinid tabulate corals dominate the shaly environments. Larger and more complex solitary and colonial rugose corals occur mainly in carbonate environments. The Mid-Carboniferous Boundary is an important faunal break. It is characterized by the disappearance of typical Mississippian solitary and colonial taxa. “Colonial aulinid” corals have only been found below and above the boundary level. The new Bashkirian coral stock shows palaeobiogeographic connections to the western United States and the Donets Basin. The studied coral fauna does not support the assignment of a Bashkirian age for strata in the Iliizi Basin and the Ahnet and Reggane basins. The Marie Legrand-Blain collection is a good example of the utility of such old collections for the study of Carboniferous corals from the often remote and hardly accessible Algerian basins.