A new specimen of<i>Guaibasaurus candelariensis</i>(basal Saurischia) from the Late Triassic Caturrita Formation of southern Brazil

Bonaparte, José F.; Brea, G.; Schultz, César Leandro; Martinelli, Agustín G.

doi:10.1080/08912960600866862

Cited by 45 publications

(57 citation statements)

References 11 publications

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“…Consequently, the overlaying Caturrita deposits can be regarded as at least Late Carnian to Early Norian in age (Zerfass et al 2003;Martinelli et al 2005). This is also supported by its faunal content (Bonaparte et al , 2003(Bonaparte et al , 2007Martinelli et al 2005). However, new stratigraphic proposals (Muttoni et al 2004;Furin et al 2006;Lehrmann et al 2006;Ovtcharova et al 2006) extends the Norian to 228 Ma, an age corresponding to the Carnian/Ladinian Zerfass et al 2003).…”

Section: Geological Setting and Biostratigraphic Commentsmentioning

confidence: 82%

“…1a,c), with an additional specimen coming from Sesmaria do Pinhal locality. There are several faunal components shared between both localities, including the ictidosaur Riograndia , the advanced probainognathians Brasilodon and Brasilitherium (Bonaparte et al 2003, the sphenodontid Clevosaurus (Bonaparte and Sues 2006;Arantes et al 2009), and the basal saurischian dinosaur Guaibasaurus (Bonaparte et al 1999(Bonaparte et al , 2007. The taxa unique to the Candelária region are the dicynodont Jachaleria (Araújo and Gonzaga 1980), an undetermined phytosaur (Kischlat and Lucas 2003), and an undetermined stereospondyl amphibian (Dias-da-Silva et al 2009).…”

Section: Geological Setting and Biostratigraphic Commentsmentioning

confidence: 97%

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New information about Irajatherium hernandezi Martinelli, Bonaparte, Schultz & Rubert 2005 (Eucynodontia, Tritheledontidae) from the upper triassic (Caturrita Formation, Paraná Basin) of Brazil

Oliveira

Martinelli²,

Soares

2010

Paläontol Z

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In this contribution, new specimens of the tritheledontid eucynodont Irajatherium hernandezi, from the Late Triassic (Caturrita Formation) of southern Brazil, are analyzed. The new material provides significant information about incisor count, canine size and shape, basicranial morphology, and other previously unknown aspects of skull and dentition. A cladistic analysis with inclusion of the new data supports the assignment of Irajatherium to Tritheledontidae, basal to Chalimininae and Pachygenelinae. Previously unknown characters of Irajatherium revealed by the new material include: the presence of three lower incisors; the first lower incisor is enlarged; the presence of large upper and lower canines with deep paracanine fossa on the maxilla; almost complete upper and lower postcanine tooth row with a pattern similar to that of other tritheledontids (e.g. Pachygenelus and Chaliminia); there is a conspicuous crest on the inner surface of the maxilla for the attachment of the inferred maxillary turbinates; partially confluent jugular foramen and fenestra rotunda within the jugular fossa, separated by a finger-like projection of the posterolateral wall of the opisthotic; and hypoglossal foramina located outside the jugular fossa. Irajatherium is a key taxon for understanding the early evolution of ictidosaurs, a group of cynodonts closely related to mammaliaforms, during the cynodont-mammal transition from the Late Triassic to Early Jurassic.

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Section: Geological Setting and Biostratigraphic Commentsmentioning

confidence: 82%

Section: Geological Setting and Biostratigraphic Commentsmentioning

confidence: 97%

New information about Irajatherium hernandezi Martinelli, Bonaparte, Schultz & Rubert 2005 (Eucynodontia, Tritheledontidae) from the upper triassic (Caturrita Formation, Paraná Basin) of Brazil

Oliveira

Martinelli²,

Soares

2010

Paläontol Z

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“…The proximal surface of the femoral head faces dorsally and has a straight profile in posteromedial view (Fig. 9C, D), as in Guaibasaurus (Bonaparte et al, 2006: fig. 8; UFRGS PV 0725T).…”

Section: Comparisonsmentioning

confidence: 97%

Basal sauropodomorphs from the Ischigualasto Formation

Martínez

Apaldetti

Abelín

2012

Journal of Vertebrate Paleontology

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ABSTRACT-Basal sauropodomorphs from the Ischigualasto Formation include Eoraptor lunensis, Panphagia protos, and Chromogisaurus novasi. Few comparisons have been made between these taxa, because Eoraptor was only recently reassessed as a basal sauropodomorph and because Panphagia and Chromogisaurus were described nearly simultaneously. We describe in detail the fully prepared bones of the holotype of Chromogisaurus novasi, examine the evidence for its taxonomic distinction, and analyze the phylogenetic relationships among basal sauropodomorphs. Our results support Chromogisaurus novasi as a valid genus and species and provide weak phylogenetic evidence favoring a series of stem taxa at the base of Sauropodomorpha. The analysis positions Panphagia as the basal-most sauropodomorph, followed by Eoraptor, Pampadromaeus, and a clade that includes Chromogisaurus and Saturnalia. RESUMEN-Los sauropodomorfos basales de la Formación Ischigualasto incluyen Eoraptor lunensis, Panphagia protos yChromogisaurus novasi. Pocas comparaciones se han hecho entre estos taxones, porque Eoraptor fue reevaluado recientemente como sauropodomorfo basal y porque Panphagia y Chromogisaurus se describieron de forma casi simultánea. Describimos en detalle los huesos totalmente preparados del holotipo de Chromogisaurus novasi, examinamos la evidencia de su distinción taxonómica, y analizamos la relación filogenética entre sauropodomorfos basales. Nuestros resultados apoyan a Chromogisaurus novasi como un género y especie válido y proporcionan débil soporte filogenético favoreciendo un arreglo parafilético en la base de Sauropodomorpha. El análisis posiciona a Panphagia como el sauropodomorfo más basal, seguido de Eoraptor, Pampadromaeus y un clado que incluye a Chromogisaurus y Saturnalia.

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“…New material of Chindesaurus from the Hayden Quarry (Irmis et al, 2007a) may help clarify its ambiguous systematic position. Guaibasaurus, from the Caturrita Formation of southern Brazil, is known from three specimens that together preserve most of the skeleton, except for the skull (Bonaparte et al, , 2007. Unfortunately, the articular ends of the bones are poorly preserved; thus, important character states of the femur, tibia, and ankle cannot be scored using available material.…”

Section: Ambiguous Taxa: Eoraptor and Herrerasauridaementioning

confidence: 99%

“…Unfortunately, the articular ends of the bones are poorly preserved; thus, important character states of the femur, tibia, and ankle cannot be scored using available material. Guaibasaurus has been considered either the sister taxon to saurischians (Bonaparte et al, , 2007 or a basal theropod (Langer, 2004;Langer and Benton, 2006;Yates, 2007a,b). Its phylogenetic position is still unresolved, but it can be confidently placed within Saurischia (Langer et al, 2007a,c).…”

Section: Ambiguous Taxa: Eoraptor and Herrerasauridaementioning

confidence: 99%

The origin and early radiation of dinosaurs

Brusatte

Nesbitt

Irmis

et al. 2010

Earth-Science Reviews

236

210

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Dinosaurs were remarkably successful during the Mesozoic and one subgroup, birds, remain an important component of modern ecosystems. Although the extinction of non-avian dinosaurs at the end of the Cretaceous has been the subject of intense debate, comparatively little attention has been given to the origin and early evolution of dinosaurs during the Late Triassic and Early Jurassic, one of the most important evolutionary radiations in earth history. Our understanding of this keystone event has dramatically changed over the past 25 years, thanks to an influx of new fossil discoveries, reinterpretations of long-ignored specimens, and quantitative macroevolutionary analyses that synthesize anatomical and geological data. Here we provide an overview of the first 50 million years of dinosaur history, with a focus on the large-scale patterns that characterize the ascent of dinosaurs from a small, almost marginal group of reptiles in the Late Triassic to the preeminent terrestrial vertebrates of the Jurassic and Cretaceous. We provide both a biological and geological background for early dinosaur history. Dinosaurs are deeply nested among the archosaurian reptiles, diagnosed by only a small number of characters, and are subdivided into a number of major lineages. The first unequivocal dinosaurs are known from the late Carnian of South America, but the presence of their sister group in the Middle Triassic implies that dinosaurs possibly originated much earlier. The three major dinosaur lineages, theropods, sauropodomorphs, and ornithischians, are all known from the Triassic, when continents were joined into the supercontinent Pangaea and global climates were hot and arid. Although many researchers have long suggested that dinosaurs outcompeted other reptile groups during the Triassic, we argue that the ascent of dinosaurs was more of a matter of contingency and opportunism. Dinosaurs were overshadowed in most Late Triassic ecosystems by crocodile-line archosaurs and showed no signs of outcompeting their rivals. Instead, the rise of dinosaurs was a two-stage process, as dinosaurs expanded in taxonomic diversity, morphological disparity, and absolute faunal abundance only after the extinction of most crocodile-line reptiles and other groups.

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A new specimen ofGuaibasaurus candelariensis(basal Saurischia) from the Late Triassic Caturrita Formation of southern Brazil

Cited by 45 publications

References 11 publications

New information about Irajatherium hernandezi Martinelli, Bonaparte, Schultz & Rubert 2005 (Eucynodontia, Tritheledontidae) from the upper triassic (Caturrita Formation, Paraná Basin) of Brazil

New information about Irajatherium hernandezi Martinelli, Bonaparte, Schultz & Rubert 2005 (Eucynodontia, Tritheledontidae) from the upper triassic (Caturrita Formation, Paraná Basin) of Brazil

Basal sauropodomorphs from the Ischigualasto Formation

The origin and early radiation of dinosaurs

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