Peixes fósseis do grupo Santana (cretáceo inferior da bacia do Araripe) da coleção de paleontologia da UERJ: aspectos taxonômicos e tafonômicos

Abstract

AraripeBasin is known worldwide by its fossil record, which allows its classifica-tion as afossillagestätte. Fossil vertebrates recovered from the Lower Cretaceous strata stand out, particularly those from the Crato and Romualdo formations of the Santana Group. Although diversified in terms of Araripe Basin fossil vertebrates, the Collection of Paleontology of the Faculty of Geology of UERJ needs a taxonomic evaluation of its fossil fishes. Furthermore, the large amount of fossil fishes in the collection can be use-ful for several taphonomic analyses. This work presents the results of taxonomic and taphonomic studies on the fossil fishes of the Santana Group (Crato and Romualdo for- mations) housed in the didactic-scientific collection of the Laboratory ofPaleontology (LABPALEO) of Faculty of Geology of UERJ. The collection of fossil fishes is com-posed of 55 specimens and 10 distinct taxa (Dastilbe crandalli, Notelops brama,Parae-lops cearensis, Rhacolepis buccalis, Tharrhias araripis, Vinctifer comptoni, Cal-amopleurus cylindricus, Cladocyclus gardneri, Neoproscinetes penalvai andBranner-ion sp.), and the species Tharrhias araripis(21 of 55 specimens, i.e. 40%) is the most abundant. In general, the specimens are preservedinside thick carbonate nodules, re-flecting high availability of calcium carbonate in the sedimentary environment and/or prolonged necrolysis. Some speciesare tridimensionally preserved, whereas the other remains are bidimensionally preserved. 3D preservation is related to a rapid genesis of the carbonate nodules, possibly influenced by microorganisms. Most of the specimens are associated; someare disarticulated or disassociated. Some fossils are diagenetically fragmented, suggesting lithostatic compression on the nodules during the fossildiagene-sis.