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Language Spanish journal of palaeontology. 2024. Vol. 39, no. 2
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- Stable isotope analysis evidences dietary changes in toxodontids (Mammalia, Notoungulata) across the Neogene-Quaternary from Argentina(2024) Sanz-Pérez, Dánae; Tomassini, Rodrigo L.; Montalvo, Claudia I.; Zurita, Alfredo; Hernández Fernández, Manuel; Domingo, LauraToxodontidae was an extinct family of South American notoungulates, widely studied systematically, but not so much from an ecological perspective. This work aims to improve the knowledge about variations in diet and habitats of different representatives of this group in the context of biotic and abiotic events throughout the last 20 My. The tooth enamel carbon isotope composition (δ13C) of 7 genera recorded in 11 localities of Central, West and Northeastern Argentina, from the Early Miocene to the Late Pleistocene, was analyzed. The diet of the toxodontids studied in this work range from mainly C3 resources during the Miocene, mixed C3-C4 in the Pliocene, to a significant consumption of C4 plants during the Pleistocene. Differences in diet during the Late Pleistocene were also recorded, associated with geographic (i.e., Northeastern vs. Central) and temporal (i.e., glacial vs. interglacial periods) variations, evidencing the adaptive capacity of the group under ecological and environmental pressures.
- First record of a mosasaurid (Squamata: Mosasauridae) from the Upper Cretaceous of Ecuador(2024) Garzon, Domenica N.; Arellano, Paul; Toro-Álava, Jorge; Román-Carrión, José Luis; E. Ordoñez, Julián; Andrade, Pamela; Mendoza-Ochoa, Carlos; Ayala, Paula; Oleas, Mateo; Vizcaino, Anthony; Jiménez-Orellana, Nelson MesíasWe report the first Upper Cretaceous marine reptile fossil in Ecuador, identified as an incomplete right maxilla from the Mosasauridae family. The remains were unearthed from marine marlstones and limestones within a karstic cave in the Tamia Yura indigenous community, situated northeast of Tena in the central Subandean Zone of the Ecuadorian Amazon. Morphological analysis reveals seven preserved teeth conical in shape. Stratigraphic analysis suggests the remains belong to the Middle Napo Fm, Oriente basin, indicating a presence from the Turonian to the end of the Coniacian. This discovery offers new insights into the study of Cretaceous marine reptiles in South America.
- Trazas fósiles marinas someras de la Formación Furada, Silúrico-Devónico de Asturias, España(2024) Ornia, Mateo; Buatois, Luis A.; Mángano, M. Gabriela; Thue, Katherine; Fernández-Martínez, Javier; Marcos, AlbertoEn los acantilados entre las playas de Munielles y Bahínas aflora la Formación Areniscas de Furada (Formación Furada), la cual marca el tránsito entre el Silúrico y el Devónico. Estos depósitos se acumularon en un ambiente marino somero afectado por sedimentación episódica, en parte como resultado de tempestades. Sobre la base del estudio de material en colecciones y nuevo trabajo de campo, se identifican, describen e ilustran 36 icnotaxones distintos: Arenicolites isp., Asterosoma ludwigae, Bergaueria hemispherica, Bifungites munizi, Chondrites isp., Cruziana acacencis, Cruziana quadrata, Curvolithus multiplex, Davichnia cantabrica, Dimorphichnus isp., Gordia marina, Halopoa imbricata, Heimdallia chatwini, Helicodromites mobilis, Helminthoidichnites tenuis, Helminthopsis abeli, Imponoglyphus isp., Lockeia siliquaria, Monomorphichnus isp. A, Monomorphichnus? isp., Nereites isp., Palaeophycus tubularis, Phycodes circinatum, Planolites montanus, Protovirgularia dichotoma, Psammichnites implexus, Psammichnites plummeri, Ptychoplasma excelsum, Rusophycus pudicus, Rusophycus isp. A e isp. B, Rosselia socialis, Skolithos isp., Teichichnus rectus, Trichophycus isp., y huellas indeterminadas. Las asociaciones documentan una amplia variedad de categorías etológicas correspondientes a diversos tipos tróficos, aunque con dominio de depositívoros y detritívoros. La asociación en su conjunto registra una diversa comunidad bentónica, si bien las suites muestran individualmente una icnodiversidad moderada a baja. La icnofauna estudiada ilustra un ejemplo silúrico-devónico de la Icnofacies de Cruziana.
- Carboniferous conulariids (Cnidaria: Scyphozoa) from Ukraine(2024) Ohar, Viktor V.; Dernov, Vitaly S.An assemblage of Carboniferous conulariids (Cnidaria) from Ukraine, consisting of Paraconularia inaequicostata (de Koninck, 1883) s.l., P. irregularis (de Koninck, 1843), P. kohli Brew & Beus, 1976, P. quadrisulcata (Sowerby, 1821), P. lata n. sp., P. cf. crustula (White, 1880), ?P. cf. subulata (Hall, 1858), ?Holoconularia rossica Van Iten et al., 2023, and ?H. poletaevi n. sp., is described. Conulariids have been collected from 15 localities, the detailed palaeontological and stratigraphic characteristics of which are summarized here. Nearly all the conulariids were found in the Donets Basin in the Serpukhovian–early Bashkirian and middle–late Moscovian intervals, which are separated from each other by an interval apparently lacking conulariids. Two new species, Paraconularia lata n. sp. and ?Holoconularia poletaevi n. sp., occur in Moscovian strata. The results of the present study confirm the ability of certain conulariids to withstand major environmental perturbations, as there are no significant changes in species composition across the mid-Carboniferous (Mississippian/Pennsylvanian) boundary. Three species, very similar to species in North America, commonly occur in Carboniferous deposits of Ukraine, namely ?Paraconularia subulata (middle Visean), P. kohli, and P. cf. crustula (Moscovian). The discovery of these three species in the Donets Basin of Ukraine underscores the cosmopolitan distribution of at least some conulariids during Carboniferous times.
- Trilobites and other fossils from the Viar River section (Cambrian Series 2, Stage 4), SW Spain(2024) Collantes, LuisThe Marianian (Cambrian Series 2) fossil assemblage of the Viar River section is here reviewed and updated, based on previous collections and new collected specimens. This section is located in southern Badajoz, southwestern Spain, and belongs to the northern branch of the Cambrian outcrops of the Ossa-Morena Zone, southwestern Iberian Massif. Specimens studied occur in the ‘Benalija beds’ of the Viar-Benalija Block. The fossil assemblage from this section is composed of the trilobites Protaldonaia morenica, Triangulaspis fusca Chelediscus garzoni and Serrodiscus bellimarginatus, the brachiopod Sibiria? sp. and the helcionellid mollusc Marocella morenensis. Protaldonaia is revised, and its classification as a subgenus of Protolenus is rejected. The species T. fusca and C. garzoni are here described and illustrated for the first time from this section. Also, new data show that C. garzoni is more broadly distributed throughout the Cambrian of the Ossa-Morena Zone. This fossil assemblages suggests a late Marianian age according to the Iberian regional biostratigraphic scheme, and it can be tentatively correlated with the early Cambrian Stage 4 at international level.
- Evaluating the paleoecology of the Megaraptora (Dinosauria: Theropoda) through biomechanical approaches(2024) Yun, Chan-gyuMegaraptoran theropods represent an enigmatic and unusual lineage of theropod dinosaurs that are characterized by their unique bauplan including a low, elongated skull and robust forelimbs with enlarged claws. Such an unusual morphology has led to speculations that these theropods primarily used forelimbs instead of jaws in prey capture or feeding, but biomechanical studies regarding in-depth evaluations of the functions of their claws or jaws have been scarce. In this work, mandibular force profiles of Australian megaraptoran Australovenator wintonensis are constructed through the principle of beam theory, and mechanical advantages of first manual unguals of various megaraptoran taxa are evaluated using third-class lever model. Mandibular force profiles reveal that the lower jaw of Australovenator wintonensisbehaved as a simple lever, suitable for delivering slashing bites, and likely unable to produce a high bite force. Biomechanical modeling of the first manual unguals of megaraptorans suggests a decrease in Mechanical Advantage in derived taxa, which indicates the claws became more adapted to hook-and-pull function during the course of evolution in this clade. Such results imply megaraptorans like Australovenator wintonensis mainly preyed on relatively small-sized animals, or relied more on their forelimbs to hunt large prey items through hooking the claws onto the victim and pulling them, tearing or slicing the flesh.
- Is palaeoanthropology being built on scientific foundations?(2024) Domíngez-Rodrigo, Manuel; Alcalá, LuisThe comparative method in palaeoanthropology has been predominant over the hypothesis-testing scientific method. Multiple interpretations over the same phenomena commonly co-exist given the relaxation of demarcation criteria. The contingent nature of non-reproducible phenomena in palaeoanthropology and the epistemological limits of the comparative method for addressing structural and more systematic palaeobiological processes have made it difficult to discern the extent to which palaeoanthropology is guided by scientific protocols. The imprint of corporative and neo-liberal policies in academia has found in essentially non-experimental disciplines a good field in which academic dynamics are ruled by patronizing networks of academic elites that produce and maintain trends, paradigms that do not need to be subjected to heuristics, research agendas frequently with specific political content, and control of the discourse of the past. Foucault argued that such a power-implanted structure is not intentional but emergent at the institutional level. This translates into a palaeoanthropological praxis that thrives on fact-collecting, and which produces interpretations that cannot be checked against any demarcation boundary to test their heuristics. This is reflected in the fact that paradigms may emerge and disappear in palaeoanthropology without need to confront them with their empirical content. Some examples are presented that justify this assertion
