A new Xenacanthiformes shark (Chondrichthyes, Elasmobranchii) from the Late Paleozoic Rio do Rasto Formation (Paraná Basin), Southern Brazil

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 semispherical 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.

El Miembro Taquaral, Formación Irati (Cuenca del Paraná, Pérmico): síntesis de estudios paleontológicos

“…The Taquaralodus albuquerquei also is known only in the Taquaral sandy facies of the State of São Paulo, without any similar fossils, being later replaced by Xenacanthidae of the genera Xenacanthus and Triodus in more recent units, Corumbataí, Teresina and Rio do Rasto formations (Würdig-Maciel, 1975;Ragonha, 1984;Pauliv et al, 2014;2017).…”

A new short-snouted rhinesuchid from the Permian of southern Brazil

“…The vertebrate fossil record of the Morro Pelado Member include fishes, temnospondyls, pareiasaurs, anomodonts, dicynodonts, dinocephalians and vertebrate ichnofossils (e.g. Barberena & Araújo, 1975;Araújo, 1984;Ragonha, 1989;Barberena, 1998;Barberena & Dias, 1998;Richter & Langer, 1998;Langer, 2000;Vega-Dias et al, 2000;Dias & Barberena, 2001;Leonardi et al, 2002;Malabarba et al, 2003;Laurini et al, 2009;Cisneros et al, 2005Cisneros et al, , 2011Cisneros et al, , 2012Silva et al, 2012;Pauliv et al, 2012Pauliv et al, , 2014Strapasson et al, 2015;Boss et al, 2016;Pacheco et al, 2016;Francischini et al, 2018).…”

The São Jerônimo da Serra Site, Rio do Rasto Formation (Middle/Upper Permian), Paraná Basin, Brazil: faciological and taphonomic context

“…The fossiliferous outcrops of the Rio do Rasto Formation provide some of the most important continental records of the Middle/Late Permian in South America ). Among vertebrates, temnospondyl amphibians (Barberena & Daemon 1974, Barberena 1998, Barberena & Dias 1998, Dias & Barberena 2001, Dias & Kroeff 2002, Dias & Schultz 2003, Malabarba et al 2003, Ramos & Vega 2011, Souza & Vega 2011, Azevedo et al 2012, Strapasson et al 2015, Eltink et al 2016, Pacheco et al 2017), a pareiasaur (Araújo 1985a, 1985b, Lee 1997, Malabarba et al 2003, Cisneros et al 2005, a basal anomodont , two dicynodonts (Barberena & Araújo 1975, Boos et al 2013, Boos et al 2016, carnivore and herbivores dinocephalians (Langer 1998, 2000, Boos et al 2015 and fishes (Richter & Langer 1998, Malabarba et al 2003, Pauliv et al 2012, Pauliv et al 2014) have been reported. Invertebrates and plants, besides ichnofossils (tetrapod tracks) and coprolites, have also been reported (Rohn 1994, Rohn & Rösler 2000, Ferreira-Oliveira 2007, Leonardi et al 2002, Silva et al 2012, Dentzien-Dias et al 2012.…”