A new genus and four new species of cladid crinoids from the Carboniferous of Oaxaca State, Mexico

摘要

Eight cladid (Subclass Cladida) crinoids are described from the Carboniferous Ixtaltepec Formation of Oaxaca State, southern Mexico. Most of the material consists of external and internal moulds of cups, arms and the proximal parts of the stem. Ekteinocrinus mixleca sp. nov. is assigned to the Order Dendrocrinida; newly recognized taxa in the Order Poteriocrinida include Stipecrinus splendidus gen. et sp. nov., Hydriocrinus amplus sp. nov. and Aesiocrinus profundus sp. nov. Cosmetocrinus sp., Contocrinus cf. kingi, an indeterminate Scytalocrinidae and a cup probably belonging to the Family Stellarocrinidae are also described. Stipecrinus splendidus sp. nov. and Cosmetocrinus sp. are Middle-Upper Mississippian (Visean-Serpukhovian), the other crinoids being Lower-Middle Pennsylvanian (Bashkirian-Moscovian). The present study reveals a strong similarity, expressed in terms of palaeobiodiversity, between the Oaxaca crinoids and those reported from Mississippian-Pennsylvanian faunas from the central-east region of North America. This similarity is also evident in the composition of the associated non-echinoderm fauna.