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Ornithodira, Dinosauromorpha New Dinosauriform (Ornithodira, Dinosauromorpha) Record from the Upper Triassic of Southern Brazil Author(s): Rodrigo Temp Müller , Max Cardoso Langer , Alex Sandro Schiller Aires and Sérgio Dias-da- silva Source: Paleontological Research, 18(2):118-121. 2014. Published By: The Palaeontological Society of Japan DOI: http://dx.doi.org/10.2517/2014PR012 URL: http://www.bioone.org/doi/full/10.2517/2014PR012 BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. 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Paleontological Research, vol. 18, no. 2, pp. 118–121, April 1, 2014 © by the Palaeontological Society of Japan doi:10.2517/2014PR012 New dinosauriform (Ornithodira, Dinosauromorpha) record from the Upper Triassic of Southern Brazil 1 2 3 RODRIGO TEMP MÜLLER , MAX CARDOSO LANGER , ALEX SANDRO SCHILLER AIRES AND SÉRGIO DIAS-DA-SILVA1 1Laboratório de Paleobiologia, Campus de São Gabriel, Universidade Federal do Pampa, Avenida Antônio Trilha, 1847, Bairro Centro, CEP 97.300-000, São Gabriel, Rio Grande do Sul, Brazil (e-mail: [email protected]) 2Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo (USP), Av. Bandeirantes, 3900, CEP 14040-901, Ribeirão Preto, São Paulo, Brazil 3Universidade Regional Integrada do Alto Uruguai e das Missões (URI) - Campus de Frederico Westphalen, Rio Grande do Sul, Brazil Received September 13, 2013; Revised manuscript accepted November 19, 2013 Key words: Carnian, Non-dinosaur dinosauriform, Paraná Basin, Santa Maria Formation, silesaurid Introduction silesaurid affinity. Institutional abbreviations.—UNIPAMPA, Universi- Dinosauriformes includes the most recent common dade Federal do Pampa, São Gabriel, Brazil. ancestor of Marasuchus lilloensis and Dinosauria, and all taxa stemming from it (Novas, 1992). The origin of this Systematic palaeontology group and its diversification have been the subject of extensive studies in recent years (Langer et al., 2010; Archosauria Cope, 1869 Langer et al., 2013), especially because it includes the Ornithodira Gauthier, 1986 dinosaur lineage, one of the most diverse groups of Dinosauromorpha Benton, 1985 Mesozoic tetrapods (Irmis, 2011; Novas et al., 2011). The Dinosauriformes Novas, 1992 oldest Dinosauriformes came from the upper Anisian of Figure 1 Tanzania (Nesbitt et al., 2010) and the Ladinian of Argentina (Romer, 1972a, b; Arcucci, 1987; Sereno and Material.—UNIPAMPA-0632, partial left femur. Arcucci, 1993) and recent studies demonstrated that non- Locality and Horizon.—Janner Site, 2 km west of dinosaur dinosauriforms shared environments with dino- Agudo, Rio Grande do Sul, Brazil. Upper portion of the saurs until the end of the Triassic (Novas and Ezcurra, Hyperodapedon Assemblage Zone (sensu Langer et al., 2005; Ezcurra, 2006; Nesbitt et al., 2010; Langer et al., 2007), upper Carnian of the Paraná Basin. 2013). Yet, the small number of available specimens Description.—The partial left femur is 110 mm long regarded as early members or possible ancestors of and sigmoid in cranial and lateral views. The proximal Dinosauria still brings great uncertainty regarding both extremity is missing, and only the distal portion of the origins and phylogenetic relationships of the group. “crest-like” fourth trochanter is preserved (Figure 1B-C). In the present contribution, we report the occurrence of The ‘lesser trochanter’ (Musculus iliofemuralis cranialis a new non-dinosaur dinosauriform specimen from the insertion) is seen on the lateral surface of the proximal Santa Maria Formation, a stratigraphic unit that congre- half of the bone as a slight proximodistally elongated gates the oldest unequivocal dinosauriform records from prominence that is completely connected to the shaft Brazil (Colbert, 1970; Langer et al., 1999; Kischlat, (Figure 1B and E). This condition differs from the knob- 1999; Da-Rosa et al., 2006; Cabreira et al., 2011), all of like ‘lesser trochanter’ of Pampadromaeus barberenai which are included within Dinosauria. One exception is (Cabreira et al., 2011), Saturnalia tupiniquim (Langer et the problematic Teyuwasu barberenai (Kischlat, 1999), al., 1999), and Sacisaurus agudoesis (Ferigolo and considered nomen dubium by Langer (2004) and revised Langer, 2007), in which the proximal portion is separated recently by Ezcurra (2012), which tentatively suggests a from the shaft by a cleft. The ‘trochanteric shelf’ is New dinosauriform femur from Brazil 119 Figure 1. Photographs and illustrations of specimen UNIPAMPA-0632. A, cranial view; B, lateral view; C, caudomedial view; D, distal view, and E, caudolateral view. absent (Figure 1E), as in Sacisaurus and differently from synapomorphies, including a popliteal fossa extending Pampadromaeus and Saturnalia. The popliteal fossa for proximally one-fourth to one-third the length of the extends for one-fourth to one-third of the shaft length femur, as observed in UNIPAMPA-0632. However, both (Figure 1C), as in Asilisaurus kongwe (Nesbitt et al., the composition and phylogenetic position of Silesauridae 2010), Eucoelophysis baldwini (Sullivan and Lucas, have been recently considered uncertain (Langer and 1999), Silesaurus opoloensis (Dzik, 2003), Sacisaurus Ferigolo, 2013), hampering the precise taxonomic attri- and Diodorus scytobrachion (Kammerer et al., 2012). bution of this specimen. Still, the absence of a protruding Some longitudinal grooves can be observed along the ‘lesser trochanter’ suggests a closer affinity to non-dino- cranial surface of the distal portion of the femur, which saur Dinosauriformes, given that all well known Triassic may correspond to points of insertion for the Musculus dinosaurs have that structure (Nesbitt, 2011; Langer and femorotibialis externus (Figure 1A). Ferigolo, 2013). The faunal content of the Janner, or Várzea do Agudo, Discussion and conclusion site resembles that of the Ischigualasto Formation, in northwestern Argentina, which shows a predominance of UNIPAMPA-0632 is assigned to Dinosauriformes due both Exaeretodon (Cabrera, 1943) and Hyperodapedon to the presence of a ‘lesser trochanter’ and a “crest-like” (Huxley in Murchison, 1859; p. 435, 436; Huxley, 1869). fourth trochanter. It does not bear any clear autapomor- [Note: The genus and species name Hyperodapedon gor- phic character, but differs from all previously known doni was introduced by Sir Roderick I. Murchison in dinosauromorphs from the Santa Maria Formation due 1859, in a postscript added in press (see References in the the combination of a ‘lesser trochanter’ completely con- present paper), the fossil having been sent by Murchison nected to the shaft and a longitudinally extensive to T. H. Huxley for identification. Murchison therein popliteal fossa. Therefore, it might represent a still attributed the name to Huxley. Consequently the genus unknown taxon from the upper portion of the Hyperoda- should be cited as Hyperodapedon Huxley in Murchison, pedon Assemblage Zone in Southern Brazil. 1859, and likewise the type species H. gordoni.] This Nesbitt et al. (2010) recognized an unnamed clade allows a direct biostratigraphic correlation and the prop- within Silesauridae, containing Asilisaurus, Eucoelophy- osition of a late Carnian age for the Janner Site (Martinez sis, Sacisaurus, and Silesaurus supported by about five et al., 2011). Because of the predominance of Exaeret- 120 Rodrigo Temp Müller et al. odon specimens, Langer et al. (2007) assigned that local- obiogeography of the earliest know dinosaur assemblages (late ity to the upper portions of the Hyperodapedon Carnian-earliest Norian). Historia Natural, Tercera Serie, vol. 2, Assemblage Zone, whereas the Sacisaurus agudoensis p. 49–71. Ferigolo, J. and Langer, M. C., 2007: A Late Triassic dinosauriform locality (also in the municipality of Agudo) belongs to from south Brazil and the origin of the ornithischian predentary the lower (upper Carnian/lower Norian) Riograndia bone. Historical Biology, vol. 19, p. 23–33. Assemblage Zone (Soares et al., 2011), within the Gauthier, J. A., 1986: Saurischian monophyly and the origin of birds. Caturrita Formation. Accordingly, UNIPAMPA-0632 is Memoirs of the California Academy of Sciences, vol. 8, p. 1–55. probably older than Sacisaurus agudoensis. Indeed, if Huxley, T. H., 1869: On Hyperodapedon. Quarterly Journal of the Geological Society of London, vol. 25, p. 138–152. UNIPAMPA-0632 corresponds to a Silesauridae, it Irmis, R. B., 2011: Evaluating hypotheses for the early diversification extends the occurrence of this clade to the Carnian of of dinosaurs. Earth and Environmental Science Transactions of Brazil. In global terms, the only two other putatively the Royal Society of Edinburgh, vol. 101,
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