Devonian chitinozoan biozones of Western Gondwana

Yngve Grahn

Abstract


A formal Devonian chitinozoan biozonation for western Gondwana is proposed. This palaeogeographic province corresponds to South America, and was located in medium to high latitudes during the Devonian. Devonian chitinozoans are known from northern Argentina, Bolivia, Brazil and eastern Paraguay. Altogether 230 localities (including wells and outcrops) are included in this study, and 171 species have been encountered. One new species, Angochitina praedensibaculata, is described. A biozonation based on the first occurrence of critical chitinozoan species is introduced. Thirteen biozones are defined: the Angochitina praedensibaculata, Angochitina strigosa, Urochitina loboi, Ramochitina magnifica, Ancyrochitina pachycerata, Ancyrochitina parisi, Alpenachitina eisenacki, Ramocllitina stiphrospinataFungochitina microspinosa - Ancyrochitina taouratinensis, Hoegisphaera glabra, Urochitina bastosi - Sommeroci1itina langei, Fungochitina fenestrata and Fungochitina ultima zones. These biozones are compared with known spore zones from the same area, and chitinozoan biozones on a global basis.


Keywords


Devonian, Western Gondwana, Chitinozoa, Biostratigraphy

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