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LOS VERTEBRADOS FÓSILES DEL PALEOZOICO Y MESOZOICO DEL ESTADO DE TOCANTINS (BRASIL): PRELIMINAR SÍNTESIS 1 THE FOSSIL VERTEBRATES OF PALEOZOIC AND MESOZOIC FROM TOCANTINS STATE (BRAZIL): A PRELIMINARY SYNTESIS

Caminhos de Geografia 11/2010; 11(36):224-236.

ABSTRACT RESUMO O registro dos vertebrados fósseis deportados no estado do Tocantins (Norte do Brasil), junto ao conhecimento geológico e paleontológico, é escasso em comparado com outros estados brasileiros. Recentemente, as faunas de vertebrados estão começando a serem descritas e analisadas, podendo aumentar a lista de taxa aqui apresentados. Esta fauna provém de cinco localidades fossilíferas, e consiste essencialmente em restos fragmentários (escamas, espinhos, dientes e etc) de paleonisciformes, elasmobranquiomorfos, celatantídeos e de um icnofóssil de Sauropoda. Os níveis sedimentares fossilíferos das rochas pertencem a Formação Pedra de Fogo (Permiano Superior) e Formação Corda (Cretácio Inferior) da Bacia do Parnaíba. ABSTRACT The occurrence of fossil vertebrates in Tocantins (Northern, Brazil) together with its knowledge of geology and paleontology is very poor compared to other states of Brazil. Recently, the vertebrate fauna started to be well described and comprehended. It consists essentially of fragmentary remains (scales, fins, teeth etc.) of paleonisciforms, elasmobranchiomorphs, coelacanthids and Sauropoda ichnofossil from five localities. The fossiliferous tocks belong to the Pedra de Fogo (Late Permian) and Corda formations (Lower Cretaceous), Parnaiba Basin.

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    ABSTRACT: The Brazilian records on Xenacanthiformes include teeth and cephalic spines from the Parnaíba, Amazonas and Paraná basins. This work describes a new species of Xenacanthidae, collected in an outcrop of Serrinha Member of Rio do Rasto Formation (Wordian to Wuchiapingian), Paraná Basin, municipality of Jacarezinho, State of Paraná. The teeth of the new species are two or three-cuspidated and the aboral surface show a smooth concavity and one rounded basal tubercle. The coronal surface presents one semi-spherical and subcircular coronal button, and also two lateral main cusps and one central (when present) with less than one fifth of the size of the lateral cusps in the labial portion. The lateral cusps are asymmetric or symmetric, rounded in transversal section, lanceolate in longitudinal section, devoid of lateral carinae and lateral serrations, and with few smooth cristae of enameloid. In optical microscope the teeth show a trabecular dentine (osteodentine) base, while the cusps are composed by orthodentine, and the pulp cavities are non-obliterated by trabecular dentine. The fossil assemblage in the same stratigraphical level and in the whole Rio do Rasto Formation indicates another freshwater record for xenacanthid sharks.
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May 17, 2014