A new Peirosauridae (Crocodyliformes Notosuchia) from the Adamantina Formation (Bauru Group, Late Cretaceous), and a new phylogenetic analysis of notosuchians
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2022-03-10
Autores
Queiroz, Marcos Vinicius Lopes
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Universidade Estadual Paulista (Unesp)
Resumo
Dentro da diversidade de fauna encontrada nos depósitos da Bacia Bauru estão os Peirosauridae. Este grupo de Notosuchia se espalha por Gondwana e possui importantes formas descritas para o Brasil. Neste trabalho descrevemos uma nova espécie de Peirosauridae com rostro de proporções platirostral ou aproximadamente tubular, encontrado na Formação Adamantina (Bacia Bauru, Cretaceo Superior). O espécime consiste em um crânio parcialmente preservado com teto craniano, região interorbital do cranio e fragmentos da porção posterior do rostro, incluindo pré-frontal e lacrimal; hemimandíbula esquerda, com 14 alvéolos e 12 dentes; e um fragmento de costela cervical. O espécime pode ser atribuida à Peirosauridae graças à existência de uma abertura ótica fechada posteriormente e em forma de triângulo, com ápice direcionado dorsalmente; à ausência de bordas supratempor ais elevadas e hipertrofiadas; por possuir a superfície lateral do flanco descendente pós-orbital côncava; e um dentário com concavidade lateral para recepção de dente maxilar alargado. O espécime foi reconhecido como uma nova espécie de Peirosauridae baseando-se em uma série de autapomorfias que o distingue de seus táxons mais proximos, tais como dentes com carenas lisas; a sua borda póstero-ventral do quadratojugal que não atinge os côndilos quadrados; as bordas distais do quadrado possuem apenas um plano voltado posteriormente; e o processo paraoccipital que em vista occipital apresenta orientação horizontal. Afim de esclarecer o posicionamento do novo espécime dentro de Peirosauridae, bem como para elucidar a topologia do grupo com a inserção de vários possíveis membros, foi realizada uma análise filogenética que contaneou dados importantes de três matrizes independentes com alta representatividade de Notosuchia, em especial os Peirosauridae. Nossos resultados indicaram para a monofilia de Peirosauridae, formado por suas grandes linhagens de Pepesuchinae e Peirosaurinae, conforme o proposto anteriormente. Paralelo a este resultado encontramos o argentino Colhuehuapisuchus lunai, descrito originalmente como um Peirosauridae, aninhado junto aos Mahajangasuchidae, ampliando assim a distribuição espacial do grupo e o consagrando como mais um grupo de Notosuchia com representatividade Gondwanica.
Peirosauridae is one of the fossil crocodyliform groups found in the Bauru Basin deposits. The fossil record of this group of Notosuchia spans across Gondwana, with important forms described for Brazil. In this work, we describe a new species of Peirosauridae that possesses a rostrum of platyrostral or nearly tubular proportions, found in the Adamantina Formation (Bauru Basin, Late Cretaceous). The specimen consists of a partially preserved skull with a cranial table, interorbital region and fragments of the posterior portion of the rostrum, including the prefrontal and lacrimal; left hemimandible, with 14 alveoli and 12 teeth; and a single cervical rib fragment. The specimen can be attributed to the Peirosauridae clade by the presence of a posteriorly closed optical opening in the form of a triangle, with a dorsally directed apex; the absence of elevated and hypertrophied supratemporal borders; for having a concave post-orbital descending process lateral surface; and a dentary with lateral concavity to receive an enlarged maxillary tooth. The new specimen was assigned to a new taxon based on a series of autapomorphies that distinguish it from its imediate sister taxa, such as teeth with smooth canines; its posteroventral border of the quadratojugal that does not reach the square condyles; the distal edges of the square have only a posteriorly facing plane; and the paraoccipital process that, in the occipital view, presents a horizontal orientation. To clarify the position of the new Peirosauridae, as well as to elucidate the topology of the group with the inclusion of several possible members, a phylogenetic analysis was performed including data from three independent matrices with increased representation of Notosuchia, especially the Peirosauridae. Our results indicated the monophyly of Peirosauridae, formed by two main lineages of Pepesuchinae and Peirosaurinae, as previously proposed. Parallel to this result, we find the Argentinian Colhuehuapisuchus lunai, originally described as a Peirosauridae, nested within the Mahajangasuchidae, thus expanding the spatial distribution of the group as another Notosuchia clade widespread in Gondwana.
Peirosauridae is one of the fossil crocodyliform groups found in the Bauru Basin deposits. The fossil record of this group of Notosuchia spans across Gondwana, with important forms described for Brazil. In this work, we describe a new species of Peirosauridae that possesses a rostrum of platyrostral or nearly tubular proportions, found in the Adamantina Formation (Bauru Basin, Late Cretaceous). The specimen consists of a partially preserved skull with a cranial table, interorbital region and fragments of the posterior portion of the rostrum, including the prefrontal and lacrimal; left hemimandible, with 14 alveoli and 12 teeth; and a single cervical rib fragment. The specimen can be attributed to the Peirosauridae clade by the presence of a posteriorly closed optical opening in the form of a triangle, with a dorsally directed apex; the absence of elevated and hypertrophied supratemporal borders; for having a concave post-orbital descending process lateral surface; and a dentary with lateral concavity to receive an enlarged maxillary tooth. The new specimen was assigned to a new taxon based on a series of autapomorphies that distinguish it from its imediate sister taxa, such as teeth with smooth canines; its posteroventral border of the quadratojugal that does not reach the square condyles; the distal edges of the square have only a posteriorly facing plane; and the paraoccipital process that, in the occipital view, presents a horizontal orientation. To clarify the position of the new Peirosauridae, as well as to elucidate the topology of the group with the inclusion of several possible members, a phylogenetic analysis was performed including data from three independent matrices with increased representation of Notosuchia, especially the Peirosauridae. Our results indicated the monophyly of Peirosauridae, formed by two main lineages of Pepesuchinae and Peirosaurinae, as previously proposed. Parallel to this result, we find the Argentinian Colhuehuapisuchus lunai, originally described as a Peirosauridae, nested within the Mahajangasuchidae, thus expanding the spatial distribution of the group as another Notosuchia clade widespread in Gondwana.
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Sistemática filogenética, Notosuchia, Peirosauridae, Pepesuchinae, Peirosaurinae, Formação Adamantina, Bacia Bauru, Phylogenetic systematics, Adamantina formation, Bauru Basin