Heitor Francischini

The oldest archosauromorph from South America: postcranial remains from the Guadalupian (mid-Permian) Rio do Rasto Formation (Paraná Basin), southern Brazil

Abstract In this contribution, we report a distal portion of a left humerus that likely belongs to an indeterminate basal archosauromorph from the Guadalupian (mid-Permian) Rio do Rastro Formation (Paraná Basin) of southern Brazil. A precise taxonomy of the fragmented and isolated humerus UFRGS-PV-0546-P is not warranted at generic nor familiar level but, likely, this specimen belongs to an Archosauromorpha due to the lack of both the entepicondylar and the ectepicondylar foramina. The narrow distal end of the humerus, the rounded radial and ulnar condyles, and the moderately developed supinator process with a shallow ectepicondylar groove (not notched) are features reminiscent of tanystropheids rather than that of other archosauromorphs. This material likely represents the first and oldest Permian archosauromorph from South America and indicates the presence of this lineage before the P/T boundary.

A new actinomycete from a Guadalupian vertebrate coprolite from Brazil

Abstract Coprolites (fossil feces) are important sources of evidence of ancient food webs and ecosystems. Actinomycetes are a fundamental component in the decay of organic matter, and serve as catalysts for nutrient cycles. Recently, gas vesicles filled with numerous verrucose colonies of substrate mycelium of an actinomycete were discovered inside a fossilized spiral amphipolar fish coprolite recovered from mid–Permian deposits of Brazil. These colonies are composed of masses of substrate hyphae, some of which are undergoing segmentation. Arising from the colonies are chains of spores separated by narrow, elongate connectives. The fossil actinomycete is described below as Palaeostromatus diairetus gen. et sp. nov. and represents the oldest known actinomycete associated with vertebrate deposits. Since the colonies occur only inside the coprolite, either Palaeostromatus diairetus gen. et sp. nov. was part of the gut flora or it was acquired from a food source. The only other remains in the coprolite are eighteen paleoniscoid fish scales, which suggests that the producer was a carnivorous/omnivorous fish. This is the oldest record of a direct interaction between vertebrates and actinomycetes.

New dinosaur remains and the tetrapod fauna from the Upper Cretaceous of Mato Grosso State, central Brazil

Abstract Mato Grosso State is the main area of paleontological investigations in central Brazil, especially regarding Upper Cretaceous beds. Fossil collection in the surroundings of the Morro do Cambambe started as early as late nineteenth century, but prospections and studies are still ongoing. This contribution presents new dinosaur specimens recovered from Upper Cretaceous outcrops of the southeastern portion of Mato Grosso State. These remains enabled the first report of a megaraptoran theropod based on a vertebral centrum and the description of abelisaurid (a fragmentary tooth) and titanosaur remains (a tooth and a fragment of a dorsal vertebra). Based on the amount of compiled reports of tetrapod remains from Mato Grosso, mainly from meeting abstracts and technical reports, the evidence at hand indicates a diverse Upper Cretaceous tetrapod assemblage still poorly explored in comparison to other Upper Cretaceous units of Brazil and Gondwana, in general.

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

Tetrapod tracks in eolianites are widespread in the fossil record since the late Paleozoic. Among these ichnofaunas, the ichnogenus Chelichnus is the most representative of the Permian tetrapod ichnological record of eolian deposits of Europe, North America and South America, where the Chelichnus Ichnofacies often occurs. In this contribution, we describe five sets of tracks (one of which is preserved in cross-section), representing the first occurrence of Dicynodontipus and Chelichnus in the “Pirambóia Formation” of southern Brazil. This unit represents a humid desert in southwestern Pangea and its lower and upper contacts lead us to consider its age as Lopingian–Induan. The five sets of tracks studied were compared with several ichnotaxa and body fossils with appendicular elements preserved, allowing us to attribute these tracks to dicynodonts and other indeterminate therapsids. Even though the “Pirambóia Formation” track record is sparse and sub-optimally preserved, it is an important key to better understand the occupation of arid environments by tetrapods across the Permo–Triassic boundary.

A MIDDLE PERMIAN (ROADIAN) LUNGFISH AESTIVATION BURROW FROM THE RIO DO RASTO FORMATION (PARANÁ BASIN, BRAZIL) AND ASSOCIATED U-Pb DATING

Abstract The Permian Rio do Rasto Formation (Paraná Basin) crops out in southern Brazil and was deposited under fluvio-lacustrine settings. A singular outcrop located in the Aceguá municipality (Rio Grande do Sul State) represents a sequence of three distinct levels of paleosols in which rhizoliths and a single vertebrate burrow were recovered. The latter has a sub-vertical orientation, a slightly curved shape and a gross morphology and simple architecture that are consistent with aestivation burrows produced by lungfishes. The occurrence of this structure, in association with the features of the paleosols, indicates a seasonal climate with drought events. Additionally, a tonstein layer is interbedded in the paleosol sequence, indicating the influence of volcanic ash falls in the paleoenvironment. Zircons were collected from this level and dated using U-Pb techniques and the obtained age is 270.61 +1.76/-3.27 Ma (Roadian). The paleoenvironmental context of this outcrop is in accordance with a dry, seasonal climate of southwestern Pangaea during the early Guadalupian.

The Presence of Ankylosaur Tracks in the Guará Formation (Brazil) and Remarks on the Spatial and Temporal Distribution of Late Jurassic Dinosaurs

ABSTRACT The Guará Formation (Paraná Basin, southern Brazil) is an Upper Jurassic unit that yielded a dinosaur ichnoassemblage composed of theropod, ornithopod, and sauropod tracks. A new set of footprints is described herein and its major features are heteropody, paraxony, and both manual and pedal tetradactyly, among others. Using ichnological, osteological, and stratigraphic approaches, we interpret these tracks as produced by an ankylosaur dinosaur. The record of these armored dinosaurs in South America is scarce and restricted to the Cretaceous units of Argentina, Bolivia, and Brazil. Therefore, the presence of these tracks in the Guará Formation provides the oldest evidence of ankylosaurs in western Gondwana and the first uncontroversial record of this group in Brazil. In addition, a comparison between the Guará Formation fossil record and other Kimmeridgian–Tithonian dinosaur-bearing units worldwide indicates that more efforts are needed to better understand the geographical distribution of Late Jurassic dinosaurs.

Bioerosion traces on titanosaurian sauropod bones from the Upper Cretaceous Marília Formation of Brazil

Paes Neto, V.D., Francischini, H., Martinelli, A.G., Marinho, T.S., Ribeiro, L.C.B., Soares, M.B. & Schultz, C.L. May.2018. Bioerosion traces on titanosaurian sauropod bones from the Upper Cretaceous Marília Formation of Brazil. Alcheringa XXX, X–X. ISSN 0311-5518. Bone bioerosions provide an important taphonomic record on fossils from continental deposits dating back to the late Paleozoic. The morphological diversity of bone bioerosions is especially high in vertebrate remains from the Late Cretaceous. Here we describe four morphotypes of bioeroson preserved on titanosaur dinosaur bones collected from the Maastrichtian Marília Formation of Brazil. These traces differ from previously described ichnotaxa, and include branching furrows and surface removal resembling insect bioerosions, channels with semicircular cross-sections consistent with either root etchings or insects, and bite traces left by vertebrates. Taphonomic sequencing shows that time-averaging was an important aspect in the genesis of the Marília Formation taphocoenosis and demonstrates that traces left on bones are significant tools for reconstructing Late Cretaceous ecosystems. Voltaire Dutra Paes Neto [voltairearts@gmail.com] and Heitor Francischini [heitorfrancischini@hotmail.com] Programa de Pós-Graduação em Geociências (PPGGEO), Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, Agronomia, 91540-000, Porto Alegre, RS, Brazil; Agustín Guillermo Martinelli* [agustin_martinelli@yahoo.com.ar], Marina Bento Soares [marina-soares@ufrgs.br] and Cesar Leandro Schultz [cesar.schultz@ufrgs.br] Instituto de Geociências (IGeo), Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, Agronomia, 91540-000, Porto Alegre, RS, Brazil; Thiago da Silva Marinho† [thiago.marinho@uftm.edu.br] Centro de Pesquisas Paleontológicas ‘Llewelyn Ivor Price’ (CPPLIP), Complexo Cultural e Científico Peirópolis (CCCP), Universidade Federal do Triângulo Mineiro (UFTM), R. Estanislau Collenghi 194, 38039-755, Peirópolis, Uberaba, MG, Brazil; Luiz Carlos Borges Ribeiro [lcbrmg@gmail.com] Centro de Pesquisas Paleontológicas ‘Llewelyn Ivor Price’ (CPPLIP), Complexo Cultural e Científico Peirópolis (CCCP), Universidade Federal do Triângulo Mineiro (UFTM), R. Estanislau Collenghi 194, 38039-755, Peirópolis, Uberaba, MG, Brazil. *Also affiliated with: Centro de Pesquisas Paleontológicas ‘Llewelyn Ivor Price’ (CPPLIP), Complexo Cultural e Científico Peirópolis (CCCP), Universidade Federal do Triângulo Mineiro (UFTM), R. Estanislau Collenghi 194, 38039-755, Peirópolis, Uberaba, MG, Brazil. †Also affiliated with: Instituto de Ciências Exatas, Naturais e Educação (ICENE), Universidade Federal do Triângulo Mineiro (UFTM), Av. Randolfo Borges Jr. 1400, Univerdecidade, 38064-200, Uberaba, MG, Brazil.