Distribution of echinoids in Jandaíra Formation

This paper discuss the occurrence of the regular echinoid species Goniopygus durandi, Rosadosoma riograndensis(Maury 1924), Phymosoma major(Coquand 1862), and the irregular echinoids Petalobrissus setifensis (Cotteau 1866), P. cubensis (Weisbord 1934), Mecaster fourneli (Agassiz & Desor 1847), M. texanus (Roemer 1852) and Mecastersp in Camurim-01, Gangorrinha-2, Gov. Dix-Sept Rosado-2, Gov. Dix-Sept Rosado-6, Estreito-1 and Frei Antonio-3, which are fossiliferous localities of Jandaíra Formation, Potiguar Basin. The sample comprises 228 specimens that were collected in 2003 and 2011. Regarding the relative abundance of the echinoid species present in Jandaíra Formation limestones, it was observed that irregular echinoids appear in a large number compared to the regular ones. Camurim-1 and Gangorrinha-2 localities stood out for having the largest abundance of species, both endocyclic and exocyclic. In Gov. Dix-Sept Rosado-2 and Gov. Dix-Sept Rosado-6 the specimens of genus Mecasterwere the only ones observed. Estreito-1 and Frei Antonio-3 had the smallest occurrence, where in the former the occurrence of regular species was observed and in the latter the occurrence of irregular ones. This occurrence pattern could be related to paleoenvironmental conditions and the species' lifestyle, because the localities with the largest biodiversity and abundance are deposited near the edge of the basin, such as Camurim-1 and Gangorrinha-2.