Palaeontologia Electronica最新文献

{"title":"Skull osteology of Aetosauroides scagliai Casamiquela, 1960 (Archosauria: Aetosauria) from the Late Triassic of Brazil: New insights into the paleobiology of aetosaurs","authors":"Voltaire D. Paes Neto, J. Desojo, A. C. B. Brust, A. M. Ribeiro, C. Schultz, M. Soares","doi":"10.26879/1120","DOIUrl":"https://doi.org/10.26879/1120","url":null,"abstract":"Aetosauroides scagliai, from the Ischigualasto Formation of Argentina and Santa Maria Supersequence of Brazil (Carnian-Norian), is one of the oldest members of Aetosauria, a diverse clade of armored crocodile-line archosaurs. Aetosauroides scagliai differs from other aetosaurs in having the maxilla excluded from the margin of the external nares, the length/width ratio of the postzygapophyses ≤ 0.75, and other features that place it as one of the earliest-diverging members of the clade. In this paper we provide a detailed description of the skull of A. scagliai based on a new Brazilian specimen, revealing that it lacks a pneumatic cavity on the medial surface of the maxilla and further differs from all other known aetosaurs by the presence of ≥ 12 dentary teeth. However, contra previous studies, the elongated posterior process of the jugal does articulate ventrally with the quadratojugal in A. scagliai, forming the posteroventral corner of the skull as in all other aetosaurs. Aetosauroides scagliai exhibits some characters typical of predatory archosaurs (like the recurved ziphodont teeth and mandibular articulation at the level of the tooth row), but was probably an omnivore, as it also shares several probable adaptations for herbivory with aetosaurs generally (i.e., edentulous anterior premaxilla and dentary) and stagonolepidoids specifically (e.g., shovel-shaped snout). This suggests that there was greater trophic diversity in this clade than usually recognized, at least early in their evolutionary history. Voltaire Dutra Paes Neto. Programa de Pós-Graduação em Geociências. Av. Bento Gonçalves 9500, Prédio 43127, 91540-000, Porto Alegre, Brazil. voltairearts@gmail.com Julia Brenda Desojo. División Paleontología Vertebrados, Museo de La Plata, Paseo del Bosque s/n°, La Plata, B1900FWA, Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET). julideso@fcnym.unlp.edu.ar Ana Carolina Biacchi Brust. Centro de Estudos e Pesquisas em Direito e Internet. Av. Roraima, 1000, 74B (3427), 97105-900, Santa Maria, Brazil. anacarolinabrust@gmail.com Ana Maria Ribeiro. Museu de Ciências Naturais do Rio Grande do Sul – SEMA/RS. Dr. Salvador França, 1427 Jardim Botânico, Porto Alegre RS, 90690-000 amaria_ribeiro@yahoo.com.br PAES NETO ET AL.: AETOSAUROIDES SKULL 2 Cesar Leandro Schultz. Programa de Pós-Graduação em Geociências. Av. Bento Gonçalves 9500, Prédio 43127, 91540-000, Porto Alegre, Brazil. cesar.schultz@ufrgs.br Marina Bento Soares. Museu Nacional, Universidade Federal do Rio de Janeiro. Parque da Quinta da Boa vista s/n 20940-040, Rio de Janeiro, RJ, Brazil. marina.soares@mn.ufrj.br","PeriodicalId":56100,"journal":{"name":"Palaeontologia Electronica","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69147296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Erugomicula, a new genus of Arcellinida (testate lobose amoebae)","authors":"N. Nasser, B. Gregory, D. Singer, R. Patterson, H. Roe","doi":"10.26879/807","DOIUrl":"https://doi.org/10.26879/807","url":null,"abstract":"Testate lobose amoebae of the order Arcellinida are a diverse, cosmopolitan group of shelled protists found in many environments, including freshwater habitats, peatlands, and soils. Their decay-resistant tests make them an important fossil group for reconstructing Quaternary environments. Within the family Difflugidae Stein, 1859 more than 300 species and 200 sub-species have been attributed to the genus Difflugia Leclerc, 1815. Although carried out on only a few taxa, molecular evidence has demonstrated that test morphology is more important than test composition in categorizing distinct taxa within the Arcellinida. The type species of Difflugia, D. proteiformis Lamarck, 1816, is characterized by a terminal aperture and an elongate acuminate test. The morphology of D. proteiformis is vastly different from most species assigned to Difflugia, explaining its polyphyletic status. We reclassify Difflugia bidens Penard, 1902 as type species of Erugomicula, a new genus within the Difflugidae, which is distinguished from other taxa within Difflugia by its broad, ovoid test, and distinct compression. Based on the compressed morphology of the test, which is not a characteristic of the Difflugiidae, we tentatively assign Erugomicula to the family Hyalospheniidae. Nawaf A. Nasser. Ottawa-Carleton Geoscience Centre and Department of Earth Sciences, Carleton University, Ottawa K1S 5B6, Canada. nawaf.nasser@carleton.ca Braden R.B. Gregory. Ottawa-Carleton Geoscience Centre and Department of Earth Sciences, Carleton University, Ottawa K1S 5B6, Canada. GregorBRB@gmail.com David Singer. Department of Zoology, Institute of Biosciences, University of São Paulo, São Paulo, Brazil and Ottawa-Carleton Geoscience Centre and Department of Earth Sciences, Carleton University, Ottawa K1S 5B6, Canada. david.singer.bio@outlook.com R. Timothy Patterson. Ottawa-Carleton Geoscience Centre and Department of Earth Sciences, Carleton University, Ottawa K1S 5B6, Canada. tim.patterson@carleton.ca Helen M. Roe. School of Natural and Built Environments, Queen’s University Belfast, Belfast, United Kingdom, BT7 1NN. h.roe@qub.ac.uk NASSER ET AL.: Erugomicula, A NEW GENUS OF ARCELLINIDA 2","PeriodicalId":56100,"journal":{"name":"Palaeontologia Electronica","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69156092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Eocene (Duchesnean and earliest Chadronian) brontotheres (Brontotheriidae), Protitanops curryi and cf. Parvicornus occidentalis, from west Texas and Mexico","authors":"Matthew C. Mihlbachler, D. Prothero","doi":"10.26879/944","DOIUrl":"https://doi.org/10.26879/944","url":null,"abstract":"Large horned brontotheres (Brontotheriidae) are abundantly represented in Duchesnean and early Chadronian mammal faunas from the Big Bend Area of West Texas and nearby Mexico. The majority of this material, which until now has never been fully examined, is identified and described. The first brontothere to be named from this region, Menodus bakeri Stovall, 1948, is found to be a nomen dubium. The majority of the fossil material is referrable to Protitanops curryi Stock, 1936. P. curryi, previously only known from a single specimen from the Titus Valley Formation of Southern California, is now recognized in both the Duchesnean and Chadronian land mammal ages of Texas. It occurs in the late Duchesnean Porvenir Local Fauna from the lower part of the Chambers Tuff Formation and from the early Chadronian Little Egypt local fauna from the upper part of the Chambers Tuff Formation and the lower Chisos Formation in the Big Bend National Park Texas. A single specimen from the early Chadronian Rancho Gaitan local fauna of the Prietos Formation of Mexico is also identified as P. curryi. The extensive Protitanops curryi material from Texas and Mexico broadens the biostratigraphic and geographic ranges of this species and provides a more extensive understanding of its morphology and phylogenetic position. Duchesneodus uintensis (Peterson, 1931) has been previously identified with diagnostic material in the Blue Cliff horizon of the lower Chambers Tuff. Duchesneodus was previously identified in the early Duchesnean Skyline Channels of the Devil’s Graveyard Formation, but this material is better identified as cf. Parvicornus occidentalis Mihlbachler and Deméré, 2009. D. uintensis is therefore restricted to the late Duchesnean in Texas. Matthew C. Mihlbachler. Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, New York 11658, USA. mmihlbac@nyit.edu Donald R. Prothero, Department of Vertebrate Paleontology, Natural History Museum of L.A. County, 900 Exposition Blvd., Los Angeles, California 90007, USA. donaldprothero@att.net MIHLBACHLER & PROTHERO: TEXAS BRONTOTHERIIDAE 2","PeriodicalId":56100,"journal":{"name":"Palaeontologia Electronica","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69155891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revisiting horseshoe crab fossils from the Middle Triassic (Anisian) Strelovec Formation Konservat-Lagerstätte of Slovenia","authors":"R. Bicknell, J. Žalohar, Primož Miklavc, B. Celarc, M. Križnar, T. Hitij","doi":"10.26879/1168","DOIUrl":"https://doi.org/10.26879/1168","url":null,"abstract":"Xiphosura are a group of marine euchelicerates with a fossil record spanning the majority of the Phanerozoic. Despite this longevity, horseshoe crab fossils are uncommon. This rarity is a result of their cuticular exoskeleton that limits the preservational potential of xiphosurid specimens. Nonetheless, a xiphosurid evolutionary radiation is recorded in Triassic-aged deposits. This event likely reflects the occupation of vacant niches after the end-Permian extinction. Here, we revisit Sloveniolimulus rudkini Bick-nell et al., 2019b—a Middle Triassic horseshoe crab from the Strelovec Formation that was previously known from one specimen—and include newly identified material to explore the validity of the taxon. We demonstrate that unique genal spine morphologies are observed in all specimens, supporting the maintenance of S. rudkini . In documenting this material, we also considered the preservational pathways for horseshoe crabs in limestone and document other metazoan groups from this as-of-yet underex-plored Konservat-Lagerstätte.","PeriodicalId":56100,"journal":{"name":"Palaeontologia Electronica","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69147152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Patagonia’s diverse but homogeneous early Paleocene forests: Angiosperm leaves from the Danian Salamanca and Peñas Coloradas formations, San Jorge Basin, Chubut, Argentina","authors":"A. Iglesias, P. Wilf, E. Stiles, Rebecca Wilf","doi":"10.26879/1124","DOIUrl":"https://doi.org/10.26879/1124","url":null,"abstract":"","PeriodicalId":56100,"journal":{"name":"Palaeontologia Electronica","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69147306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tooth enamel microstructure in North American Phytosauria (Diapsida:Archosauriformes): Implications for biogeography and ecology of a Late Triassic clade of crocodylian-like predators","authors":"Devin K. Hoffman, Jess Miller-Camp, A. Heckert","doi":"10.26879/1162","DOIUrl":"https://doi.org/10.26879/1162","url":null,"abstract":"Teeth can provide important insight into diet and evolution of extinct vertebrates. Tooth enamel microstructure records functional and phylogenetic signals beyond the gross morphology of the dentition. Here , we provide the first systematic sampling of phytosaur tooth enamel to address questions of intra-and interspecific variation, and thus taxonomic identification, biogeographic connectivity, and heterodonty. We sampled 23 phytosaur teeth from five localities throughout the American Southwest and one locality from the Newark Supergroup of North Carolina. These teeth probably represent five heterodont genera and are tentatively assigned to Angistorhinus, Smilosu-chus, Machaeroprosopus, Redondasaurus, and “Rutiodon” . We used scanning electron microscopy to examine their enamel microstructure from transverse, longitudinal, and tangential cross-sections. All sampled teeth are composed of columnar enamel ranging in thickness from 20 to 150 µm, typically 50–100 µm, across all","PeriodicalId":56100,"journal":{"name":"Palaeontologia Electronica","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69147036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paleoecology of the Rhinocerotidae (Mammalia, Perissodactyla) from Béon 1, Montréal-du-Gers (late early Miocene, SW France): Insights from dental microwear texture analysis, mesowear, and enamel hypoplasia","authors":"M. Hullot, Y. Laurent, G. Merceron, P. Antoine","doi":"10.26879/1163","DOIUrl":"https://doi.org/10.26879/1163","url":null,"abstract":"The late early Miocene Béon 1 locality has yielded an abundant vertebrate fauna with more than 5,000 remains assigned to four rhinocerotid species: the stem rhinocerotine Plesiaceratherium mirallesi, the teleoceratines Prosantorhinus douvillei and Brachypotherium brachypus , and the early-diverging elasmotheriine Hispanotherium beonense . Such a profusion of closely related large herbivore species co-occurring raises questions about habitat capacity and niche partitioning. To investigate potential niche partitioning of Béon 1 rhinocerotids, we studied their ecology through texture microwear stress between the low scores suggesting browsing preferences, microwear subtle dietary","PeriodicalId":56100,"journal":{"name":"Palaeontologia Electronica","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69147049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The axial skeleton of Bagualia alba (Dinosauria: Eusauropoda) from the Early Jurassic of Patagonia","authors":"K. Gómez, J. Carballido, D. Pol","doi":"10.26879/1176","DOIUrl":"https://doi.org/10.26879/1176","url":null,"abstract":"Sauropod dinosaurs were the dominant large-bodied herbivores in many Mesozoic terrestrial ecosystems. Such predominance took place after a faunal replacement event linked to a global environmental change during the Early Jurassic (Pliensbachian–Toarcian), when the smaller basal sauropodomorphs were replaced by giant forms in the subclade Eusauropoda. Two main characteristics of this latter group are large body size (exceeding 10 tons) and a remarkably long neck. New data is presented on the axial anatomy of one of the earliest known eusauropods, Bagualia alba from the Toarcian levels of the Cañadón Asfalto Formation (Chubut Province, Argentina), which bear on the origins of these characteristics. Optimizing relevant axial characters on sauropodomorph phylogeny highlights important changes in cervical anatomy in the evolution of Sauropoda: a greater elongation of the neck due to both an increase in the vertebral count and the elongation of each cervical vertebra, and the appearance of pneumatic structures, first on the external surface (e.g., pleurocoels, laminae within the pleurocoels, accessory laminae of the neural arch) and subsequently invading the internal body of the vertebrae. These two changes have been considered essentials for body mass increase in Eusauropoda. The Toarcian age of Bagualia indicates that several important modifications in the axial skeleton and especially the neck occurred early in eusauropod evolution. These modifications are of ecomorphological importance and likely influenced the success of the eusauropods during the climatic changes surrounding the Pliensbachian–Toarcian crisis. Kevin Leonel Gomez. Consejo Nacional de Investigaciones Científicas y Técnicas, Museo Paleontológico Egidio Feruglio, Fontana 140, 9100, Trelew, Argentina. kgomez@mef.org.ar Jose Luis Carballido. Consejo Nacional de Investigaciones Científicas y Técnicas, Museo Paleontológico Egidio Feruglio, Fontana 140, 9100, Trelew, Argentina. jcarballido@mef.org.ar Diego Pol. Consejo Nacional de Investigaciones Científicas y Técnicas, Museo Paleontológico Egidio Feruglio, Fontana 140, 9100, Trelew, Argentina. dpol@mef.org.ar","PeriodicalId":56100,"journal":{"name":"Palaeontologia Electronica","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69147447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Late Cretaceous Elopomorpha (Actinopterygii: Teleostei) from the Mahajanga Basin of Madagascar and impacts on paleobiogeography","authors":"Summer Ostrowski","doi":"10.26879/1151","DOIUrl":"https://doi.org/10.26879/1151","url":null,"abstract":",","PeriodicalId":56100,"journal":{"name":"Palaeontologia Electronica","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69146880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geometric morphometrics in ammonoids based on virtual modelling","authors":"D. Morón-Alfonso, R. Hoffmann, Marcela Cichowolski","doi":"10.26879/1157","DOIUrl":"https://doi.org/10.26879/1157","url":null,"abstract":"Linear morphometrics is the most widely applied technique to study the variation of the conch morphology in ammonoids and other ectocochleate cephalopods. However, because this method frequently relies upon a few linear measurements, it lacks the explanatory power to accurately characterize the shape of the whorl cross-section, which is instead discussed solely in descriptive terms, e.g., elliptical, triangular, or sub-quadrate. Here, we introduce a landmark-based geometric morphometric approach to study ammonoid whorl cross-sections, derived from the regularly used morphometric parameters in cephalopods. This new technique uses virtual modelling to generate semilandmark configurations and virtual models of whorl cross-sections. We applied it to study 50 ammonoid specimens belonging to 48 genera exhibiting a wide range of morphologies and ages. Results indicate that this new method is appropriate to describe the shape of ammonoid whorl cross-sections, allowing us to construct a mor-phospace showing several biological patterns (e.g., clustering and homeomorphy), and complex morphological transformations that, in some cases, correlate with evolutionary tendencies described by previous authors. Further, this technique can be used to generate the basic segment required for the elaboration of the virtual models employed in hydrostatic and hydrodynamic studies.","PeriodicalId":56100,"journal":{"name":"Palaeontologia Electronica","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69146979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}