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Aranciaga Rolando AM, Novas FE, Calvo JO, Porfiri JD, Dos Santos DD, Lamanna MC. Reconstruction of the pectoral girdle and forelimb musculature of Megaraptora (Dinosauria: Theropoda). Anat Rec (Hoboken) 2023. [PMID: 36647300 DOI: 10.1002/ar.25128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 09/18/2022] [Accepted: 11/06/2022] [Indexed: 01/18/2023]
Abstract
Megaraptora is a group of enigmatic, carnivorous non-avian theropod dinosaurs from the Cretaceous of Asia, Australia, and especially South America. Perhaps the most striking aspect of megaraptoran morphology is the large, robustly constructed forelimb that, in derived members of the clade, terminates in a greatly enlarged manus with hypertrophied, raptorial unguals on the medialmost two digits and a substantially smaller ungual on digit III. The unique forelimb anatomy of megaraptorans was presumably associated with distinctive functional specializations; nevertheless, its paleobiological significance has not been extensively explored. Here we draw from observations of the pectoral girdle and forelimb skeletons of Megaraptora and myological assessments of other archosaurian taxa to provide a comprehensive reconstruction of the musculature of this anatomical region in these singular theropods. Many muscle attachment sites on megaraptoran forelimb bones are remarkably well developed, which in turn suggests that the muscles themselves were functionally significant and important to the paleobiology of these theropods. Furthermore, many of these attachments became increasingly pronounced through megaraptoran evolutionary history, being substantially better developed in derived taxa such as Australovenator wintonensis and especially Megaraptor namunhuaiquii than in early branching forms such as Fukuiraptor kitadaniensis. When considered alongside previous range of motion hypotheses for Australovenator, our results indicate that megaraptorans possessed a morphologically and functionally specialized forelimb that was capable of complex movements. Notable among these were extensive extension and flexion, particularly in the highly derived manus, as well as enhanced humeral protraction, attributes that very probably aided in prey capture.
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Affiliation(s)
| | - Fernando E Novas
- Museo Argentino de Ciencias Naturales "Bernardino Rivadavia," CONICET, CABA, Argentina
| | - Jorge O Calvo
- Grupo de Transferencia Proyecto Dino, CIGPat, Facultad de Ingeniería, Departamento de Geología y Petróleo, Universidad Nacional del Comahue, Neuquén, Argentina.,Parque Natural Geo-Paleontológico Proyecto Dino, Grupo de Transferencia Proyecto Dino, Facultad de Ingeniería, Universidad Nacional del Comahue, Neuquén, Argentina.,Facultad de Ciencias Exactas y Naturales, Universidad Nacional de la Pampa, Santa Rosa, La Pampa, Argentina
| | - Juan D Porfiri
- Museo de Ciencias Naturales, Universidad Nacional del Comahue, Neuquén, Argentina.,Cátedra de Reptiles Mesozoicos, Facultad de Ingeniería, Universidad Nacional del Comahue, Neuquén, Argentina.,Museo del Desierto Patagónico de Añelo, Municipalidad de Añelo/Universidad Nacional del Comahue, Neuquén, Argentina
| | - Domenica D Dos Santos
- Museo de Ciencias Naturales, Universidad Nacional del Comahue, Neuquén, Argentina.,Cátedra de Reptiles Mesozoicos, Facultad de Ingeniería, Universidad Nacional del Comahue, Neuquén, Argentina.,Museo del Desierto Patagónico de Añelo, Municipalidad de Añelo/Universidad Nacional del Comahue, Neuquén, Argentina
| | - Matthew C Lamanna
- Section of Vertebrate Paleontology, Carnegie Museum of Natural History, Pittsburgh, Pennsylvania, USA
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Aranciaga Rolando AM, Cerroni MA, Novas FE. Skull Anatomy and Pneumaticity of the Enigmatic Coelurosaurian Theropod Bicentenaria argentina. Anat Rec (Hoboken) 2019; 303:1884-1900. [PMID: 31595689 DOI: 10.1002/ar.24288] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 08/21/2019] [Accepted: 08/28/2019] [Indexed: 11/12/2022]
Abstract
The enigmatic basal coelurosaur Bicentenaria argentina is a small theropod that comes from the Upper Cretaceous of Patagonia. It is constituted by more than 130 elements, including cranial remains. These are represented by an incomplete snout, palate, dermatocranium, and lower jaws still in articulation. The skull material of Bicentenaria was preliminarily studied by previous authors. In this study, we conducted a CT scan of the holotype of Bicentenaria, which allowed us to fully describe all preserved skull bones, including some previously unknown elements. The morphological analysis indicates that Bicentenaria shares many cranial features with other basal coelurosaurs as compsognathids, Ornitholestes, and tyrannosauroids. Otherwise, results of this analysis show that Bicentenaria exhibits a set of traits unique to this taxon. Furthermore, several pneumatic recesses were closely matched with those pneumatic features present in many derived coelurosaurs, particularly tyrannosauroids. This new information, together with future discoveries, will improve our knowledge about the muscular correlates of Bicentenaria and other coelurosaurs, and may shed light about the phylogenetic relationships of this group. Anat Rec, 2019. © 2019 American Association for Anatomy Anat Rec, 303:1884-1900, 2020. © 2019 American Association for Anatomy.
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Affiliation(s)
- Alexis M Aranciaga Rolando
- Laboratorio de Anatomía Comparada y Evolución de los Vertebrados, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Buenos Aires, Argentina
| | - Mauricio A Cerroni
- Laboratorio de Anatomía Comparada y Evolución de los Vertebrados, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Buenos Aires, Argentina
| | - Fernando E Novas
- Laboratorio de Anatomía Comparada y Evolución de los Vertebrados, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Buenos Aires, Argentina
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