Pegadas teromorfóides do Triássico Superior (Formação Santa Maria) do Sul do Brasil

Abstract

Resumo Pistas de vertebrados do Triássico são abundantes em todo o mundo, mas apenas recentemente foram encontradas na Formação Santa Maria (Triássico Médio a Superior, Sul do Brasil), apesar do rico registro osteológico presente nessa unidade. O material estudado consiste em amostras contendo pegadas e pistas teromorfóides procedentes do afloramento Predebon (porção superior do Membro Alemoa, Formação Santa Maria), situado no Município de São João do Polêsine, Estado do Rio Grande do Sul. Algumas das pegadas encontradas foram atribuídas a Dicynodontipus isp., ao passo que outras foram descritas como Dicynodontipus protherioides isp. nov. Algumas pegadas associadas a estas não puderam ser identificadas, sendo então classificadas como Incertae sedis. As pegadas estudadas não correspondem a subpegadas (undertracks) e foram produzidas em substrato encharcado e muito plástico, tendo ocorrido um breve período de exposição subaérea levando ao endurecimento da superfície antes do seu soterramento. O animal produtor de Dicynodontipus protherioides isp. nov. era quadrúpede, cursorial, com andar alternado e postura semi-ereta, mas tinha pouca flexão lateral da coluna vertebral; os autopódios eram plantígrados a semiplantígrados, sem garras e com almofadas falangeais e plantares. As pistas foram produzidas com andar caminhado e com a cauda tocando o chão. A distância gleno-acetabular do produtor dessas pegadas foi calculada como 2,68 cm. As pegadas estudadas, incluindo Dicynodontipus protherioides isp. nov. e Dicynodontipus isp., podem ser atribuídas a cinodontes de pequeno porte, cujos esqueletos são encontrados nas formações Santa Maria e Caturrita.Palavras-chave: Dicynodontipus protherioides isp. nov., pegadas teromorfóides, cinodontes, Triássico Superior, Bacia do Paraná. Abstract Theromorphoid footprints from late triassic (Santa Maria formation) of southern Brazil.Tracks of triassic vertebrates are abundant all over the world, but they were discovered only recently in Santa Maria Formation (Middle-Late Triassic, Southern Brazil), despite the rich osteological record in this unit. The studied material consists of rock samples containing theromorphoid footprints and tracks from Predebon outcrop (upper portion of Alemoa Member, Santa Maria Formation), located in the municipality of São João do Polêsine, Rio Grande do Sul State. Some of the footprints had been attributed to Dicynodontipus isp., while others had been described as Dicynodontipus protherioides isp. nov. Some footprints associated to these could not have been identified, being classified as Incertae sedis. The studied footprints do not correspond to undertracks and were produced in wet and very plastic substrate. After their production, a brief period of subaerial exposure leads to the hardening of the surface before its burial. The trackmaker of Dicynodontipus protherioides isp. nov. was quadrupedal, cursorial, with alternate pace and half-erect gait, but with little lateral movement of the vertebral column; the autopodia were plantigrade to semiplantigrade...

Tetrapod tracks in Permo–Triassic eolian beds of southern Brazil (Paraná Basin)

“…Some years later, Haubold (1971a , 1971b ) reinterpreted both materials as D. geinitzi . Since then, several authors (e.g., Conti et al, 1977 ; Retallack, 1996 ; Melchor & de Valais, 2006 ; Silva et al, 2008 ; Silva, Sedor & Fernandes, 2012 ; Marchetti, Voigt & Klein, 2017 , among others) have followed Haubold’s (1971a , 1971b ) assignment, using D. geinitzi as the type-ichnospecies of Dicynodontipus. However, this is contrary to the Paragraph 61.1.3. of the Article 61 of the International Code of Zoological Nomenclature ( ICZN, 1999 ), which claims that “the name-bearing type of any nominal taxon, once fixed in conformity with the provisions of the Code, is not subject to change.” Therefore, D. hildburghausensis must be considered the type-material of the ichnogenus Dicynodontipus , even if the name D. geinitzi is considered a senior synonym.…”

“…This record was later revisited by Silva, Sedor & Fernandes (2012) , who proposed a new ichnospecies: D. penugnu . Silva et al (2008) described D. protherioides from the Upper Triassic deposits of the Alemoa Member of the Santa Maria Formation ( Hyperodapedon Assemblage Zone; Candelária Sequence) of the Rio Grande do Sul State, in southern Brazil. But these materials were reinterpreted by Klein, Lucas & Voigt (2015) as belonging to Procolophonichnium.…”

Possible eucynodont (Synapsida: Cynodontia) tracks from a lacustrine facies in the Lower Jurassic Moenave Formation of southwestern Utah

“…, Conti et al, 1977 ; Retallack, 1996 ; Rühle von Lilienstern, 1944 ), Dicynodontipus tracks likely were made by cynodont therapsids ( e.g. , Da Silva et al, 2008 ; Haubold, 1971 ; Haubold, 1984 ; Marsicano et al, 2004 ). If correct, and if all tracks referred to this ichnogenus truly belong in it, then the temporal extent of this ichnogenus suggests that cynodont manus and pedes were evolutionarily rather conservative from the Permian through the Triassic.…”

A new herrerasaurid dinosaur record from southern BrazilL (Upper Triassic) and its faunal association

“…Besides the ichnofossils, the remaining fossils for the Predebon Site correspond to rhynchosaur elements, some of which were assigned to Hyperodapedon sp., based on cranial traits, by Baó et al (2016). Silva et al (2022) proposed that some rhyncosaur specimens can be referred to Hyperodapedon mariensis (Tupi-Caldas, 1933). In addition to rhynchosaurs, isolated teeth of archosauriforms and postcranial elements of indeterminate dinosaurs are also found, as well as the vertebrae attributed here to Herrerasauridae.…”