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Meade LE, Pittman M, Balanoff A, Lautenschlager S. Cranial functional specialisation for strength precedes morphological evolution in Oviraptorosauria. Commun Biol 2024; 7:436. [PMID: 38600295 PMCID: PMC11006937 DOI: 10.1038/s42003-024-06137-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 04/02/2024] [Indexed: 04/12/2024] Open
Abstract
Oviraptorosaurians were a theropod dinosaur group that reached high diversity in the Late Cretaceous. Within oviraptorosaurians, the later diverging oviraptorids evolved distinctive crania which were extensively pneumatised, short and tall, and had a robust toothless beak, interpreted as providing a powerful bite for their herbivorous to omnivorous diet. The present study explores the ability of oviraptorid crania to resist large mechanical stresses compared with other theropods and where this adaptation originated within oviraptorosaurians. Digital 3D cranial models were constructed for the earliest diverging oviraptorosaurian, Incisivosaurus gauthieri, and three oviraptorids, Citipati osmolskae, Conchoraptor gracilis, and Khaan mckennai. Finite element analyses indicate oviraptorosaurian crania were stronger than those of other herbivorous theropods (Erlikosaurus and Ornithomimus) and were more comparable to the large, carnivorous Allosaurus. The cranial biomechanics of Incisivosaurus align with oviraptorids, indicating an early establishment of distinctive strengthened cranial biomechanics in Oviraptorosauria, even before the highly modified oviraptorid cranial morphology. Bite modelling, using estimated muscle forces, suggests oviraptorid crania may have functioned closer to structural safety limits. Low mechanical stresses around the beaks of oviraptorids suggest a convergently evolved, functionally distinct rhamphotheca, serving as a cropping/feeding tool rather than for stress reduction, when compared with other herbivorous theropods.
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Affiliation(s)
- Luke E Meade
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK.
| | - Michael Pittman
- School of Life Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Amy Balanoff
- Center for Functional Anatomy and Evolution, Johns Hopkins University School of Medicine, Baltimore, USA
| | - Stephan Lautenschlager
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
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2
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Atkins-Weltman KL, Simon DJ, Woodward HN, Funston GF, Snively E. A new oviraptorosaur (Dinosauria: Theropoda) from the end-Maastrichtian Hell Creek Formation of North America. PLoS One 2024; 19:e0294901. [PMID: 38266012 PMCID: PMC10807829 DOI: 10.1371/journal.pone.0294901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 11/08/2023] [Indexed: 01/26/2024] Open
Abstract
Caenagnathidae is a clade of derived, Late Cretaceous oviraptorosaurian theropods from Asia and North America. Because their remains are rare and often fragmentary, caenagnathid diversity is poorly understood. Anzu wyliei is the only caenagnathid species currently described from the late Maastrichtian Hell Creek Formation of the USA and is also among the largest and most completely preserved North American caenagnathids. Smaller, less complete caenagnathid material has long been known from the Hell Creek Formation, but it is unclear whether these are juvenile representatives of Anzu or if they represent distinct, unnamed taxa. Here, we describe a relatively small caenagnathid hindlimb from the Hell Creek Formation, and conduct osteohistological analysis to assess its maturity. Histological data and morphological differences from Anzu wyliei and other caenagnathids allow us to conclude that this specimen represents a new species of caenagnathid from the Hell Creek Formation, with a smaller adult body size than Anzu. This new taxon is also distinct from other small caenagnathid material previously described from the area, potentially indicating the coexistence of three distinct caenagnathid species in the Hell Creek Formation. These results show that caenagnathid diversity in the Hell Creek ecosystem has been underestimated.
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Affiliation(s)
| | - D. Jade Simon
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | | | | | - Eric Snively
- Oklahoma State University, Tahlequah, OK, United States of America
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3
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Kubo K, Kobayashi Y, Chinzorig T, Tsogtbaatar K. A new alvarezsaurid dinosaur (Theropoda, Alvarezsauria) from the Upper Cretaceous Baruungoyot Formation of Mongolia provides insights for bird-like sleeping behavior in non-avian dinosaurs. PLoS One 2023; 18:e0293801. [PMID: 37967055 PMCID: PMC10651048 DOI: 10.1371/journal.pone.0293801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 10/19/2023] [Indexed: 11/17/2023] Open
Abstract
Alvarezsauria is a group of early-branching maniraptoran theropods that are distributed globally from the Late Jurassic to the latest Cretaceous. Despite recent increases in the fossil record of this group, the scarcity of complete specimens still restricts interpreting their detailed anatomy, ecology, and evolution. Here, we report a new taxon of derived alvarezsaur, Jaculinykus yaruui gen. et sp. nov., from the Late Cretaceous of Mongolia, which represents a nearly complete and articulated skeleton. Our phylogenetic analysis reveals that Jaculinykus belongs to the sub-clade of Alvarezsauridae, Parvicursorinae, and forms a mononphyletic group with Mononykus and Shuvuuia. Its well-preserved manus has only two fingers, composed of a hypertrophied digit I and greatly reduced digit II, which implies an intermediate condition between the tridactyl manus of Shuvuuia and monodactyl manus of Linhenykus. This highlights a previously unrecognized variation in specialization of alvarezsaurid manus. Notably, the preserved posture of the specimen exhibits a stereotypical avian-like sleeping position seen in the troodontids Mei and Sinornithoides. Evidence of this behavior in the alvarezsaur Jaculinykus suggests that stereotypically avian sleeping postures are a maniraptoran synapomorphy, providing more evidence of bird-like traits being distributed broadly among avian ancestors.
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Affiliation(s)
- Kohta Kubo
- Department of Natural History and Planetary Sciences, Hokkaido University, Kita-ku, Sapporo, Hokkaido, Japan
| | | | - Tsogtbaatar Chinzorig
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, United States of America
- Institute of Paleontology, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia
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4
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Wang S, Ma Y, Wu Q, Wang M, Hu D, Sullivan C, Xu X. Digital restoration of the pectoral girdles of two Early Cretaceous birds, and implications for early flight evolution. eLife 2022; 11:76086. [PMID: 35356889 PMCID: PMC9023055 DOI: 10.7554/elife.76086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 03/30/2022] [Indexed: 11/30/2022] Open
Abstract
The morphology of the pectoral girdle, the skeletal structure connecting the wing to the body, is a key determinant of flight capability, but in some respects is poorly known among stem birds. Here, the pectoral girdles of the Early Cretaceous birds Sapeornis and Piscivorenantiornis are reconstructed for the first time based on computed tomography and three-dimensional visualization, revealing key morphological details that are important for our understanding of early-flight evolution. Sapeornis exhibits a double articulation system (widely present in non-enantiornithine pennaraptoran theropods including crown birds), which involves, alongside the main scapula-coracoid joint, a small subsidiary joint, though variation exists with respect to the shape and size of the main and subsidiary articular contacts in non-enantiornithine pennaraptorans. This double articulation system contrasts with Piscivorenantiornis in which a spatially restricted scapula-coracoid joint is formed by a single set of opposing articular surfaces, a feature also present in other members of Enantiornithines, a major clade of stem birds known only from the Cretaceous. The unique single articulation system may reflect correspondingly unique flight behavior in enantiornithine birds, but this hypothesis requires further investigation from a functional perspective. Our renderings indicate that both Sapeornis and Piscivorenantiornis had a partially closed triosseal canal (a passage for muscle tendon that plays a key role in raising the wing), and our study suggests that this type of triosseal canal occurred in all known non-euornithine birds except Archaeopteryx, representing a transitional stage in flight apparatus evolution before the appearance of a fully closed bony triosseal canal as in modern birds. Our study reveals additional lineage-specific variations in pectoral girdle anatomy, as well as significant modification of the pectoral girdle along the line to crown birds. These modifications produced diverse pectoral girdle morphologies among Mesozoic birds, which allowed a commensurate range of capability levels and styles to emerge during the early evolution of flight.
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Affiliation(s)
- Shiying Wang
- Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| | - Yubo Ma
- University of Alberta, Edmonton, Canada
| | - Qian Wu
- Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| | - Min Wang
- Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| | - Dongyu Hu
- Paleontological Museum of Liaoning, Shenyang Normal University, Shenyang, China
| | | | - Xing Xu
- Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
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5
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Xing L, Niu K, Ma W, Zelenitsky DK, Yang TR, Brusatte SL. An exquisitely preserved in-ovo theropod dinosaur embryo sheds light on avian-like prehatching postures. iScience 2022; 25:103516. [PMID: 35106456 PMCID: PMC8786642 DOI: 10.1016/j.isci.2021.103516] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 11/14/2021] [Accepted: 11/22/2021] [Indexed: 11/20/2022] Open
Abstract
Despite the discovery of many dinosaur eggs and nests over the past 100 years, articulated in-ovo embryos are remarkably rare. Here we report an exceptionally preserved, articulated oviraptorid embryo inside an elongatoolithid egg, from the Late Cretaceous Hekou Formation of southern China. The head lies ventral to the body, with the feet on either side, and the back curled along the blunt pole of the egg, in a posture previously unrecognized in a non-avian dinosaur, but reminiscent of a late-stage modern bird embryo. Comparison to other late-stage oviraptorid embryos suggests that prehatch oviraptorids developed avian-like postures late in incubation, which in modern birds are related to coordinated embryonic movements associated with tucking - a behavior controlled by the central nervous system, critical for hatching success. We propose that such pre-hatching behavior, previously considered unique to birds, may have originated among non-avian theropods, which can be further investigated with additional discoveries of embryo fossils.
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Affiliation(s)
- Lida Xing
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China
- School of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China
- Yingliang Stone Nature History Museum, Nan'an 362300, China
| | - Kecheng Niu
- Yingliang Stone Nature History Museum, Nan'an 362300, China
| | - Waisum Ma
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
| | | | - Tzu-Ruei Yang
- Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
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6
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Bi S, Amiot R, Peyre de Fabrègues C, Pittman M, Lamanna MC, Yu Y, Yu C, Yang T, Zhang S, Zhao Q, Xu X. An oviraptorid preserved atop an embryo-bearing egg clutch sheds light on the reproductive biology of non-avialan theropod dinosaurs. Sci Bull (Beijing) 2021; 66:947-954. [PMID: 36654242 DOI: 10.1016/j.scib.2020.12.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 12/02/2020] [Accepted: 12/03/2020] [Indexed: 01/20/2023]
Abstract
Recent studies demonstrate that many avialan features evolved incrementally prior to the origin of the group, but the presence of some of these features, such as bird-like brooding behaviours, remains contentious in non-avialan dinosaurs. Here we report the first non-avialan dinosaur fossil known to preserve an adult skeleton atop an egg clutch that contains embryonic remains. The preserved positional relationship of the adult to the clutch, coupled with the advanced growth stages of the embryos and their high estimated incubation temperatures, provides strong support for the brooding hypothesis. Furthermore, embryos in the clutch are at different developmental stages, suggesting the presence of asynchronous hatching-a derived feature even among crown-group birds-in non-avialan theropods. These findings demonstrate that the evolution of reproductive biology along bird-line archosaurs was a complex rather than a linear and incremental process, and suggest that some aspects of non-avialan theropod reproduction were unique to these dinosaurs.
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Affiliation(s)
- Shundong Bi
- Centre for Vertebrate Evolutionary Biology, Institute of Palaeontology, Yunnan University, Kunming 650091, China; Department of Biology, Indiana University of Pennsylvania, Indiana, PA 15705, USA.
| | - Romain Amiot
- Univ Lyon, Univ Lyon 1, ENSL, CNRS, LGL-TPE, Villeurbanne, F-69622, France
| | - Claire Peyre de Fabrègues
- Centre for Vertebrate Evolutionary Biology, Institute of Palaeontology, Yunnan University, Kunming 650091, China
| | - Michael Pittman
- Vertebrate Palaeontology Laboratory, Division of Earth and Planetary Science, The University of Hong Kong, Hong Kong, China
| | - Matthew C Lamanna
- Section of Vertebrate Paleontology, Carnegie Museum of Natural History, Pittsburgh, PA 15213, USA
| | - Yilun Yu
- Yuanpei College, Peking University, Beijing 100871, China
| | - Congyu Yu
- Division of Paleontology, American Museum of Natural History, New York, NY 10024, USA
| | - Tzuruei Yang
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China; Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing 100044, China
| | - Shukang Zhang
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China; Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing 100044, China
| | - Qi Zhao
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China; Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing 100044, China
| | - Xing Xu
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China; Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing 100044, China.
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7
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Cuesta E, Vidal D, Ortega F, Shibata M, Sanz JL. Pelecanimimus (Theropoda: Ornithomimosauria) postcranial anatomy and the evolution of the specialized manus in Ornithomimosaurs and sternum in maniraptoriforms. Zool J Linn Soc 2021. [DOI: 10.1093/zoolinnean/zlab013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
Pelecanimimus polyodon was discovered in 1993 in the Spanish Barremian fossil site of Las Hoyas, being the first ornithomimosaur described from Europe. So far, there has been no detailed description of the holotype of Pelecanimimus, which is composed of the anterior-half of an articulated skeleton. Here we report a new, detailed, revised and more accurate osteological description of its postcranial skeleton, comparing this new data to information about Ornithomimosauria from the last three decades. This osteological and phylogenetic analysis of Pelecanimimus shows several ornithomimosaur synapomorphies and a unique combination of characters that emend its original diagnosis. Pelecanimimus diverged early in Ornithomimosauria and reveals an enlargement trend of the manus, shared with derived ornithomimosaurians, due to a long metacarpal I and elongated distal phalanges. This evolutionary novelty, and other synapomorphies, has led to the definition of a new clade, Macrocheiriformes, including Pelecanimimus and more derived ornithomimosaurs. Pelecanimimus has the only ossified sternal plates among ornithomimosaurs and the first evidence of uncinate processes in a non-maniraptoran theropod, indicating a convergent appearance of these structures in Coelurosauria. The character combination in an early-diverging ornithomimosaur like Pelecanimimus found in this analysis provides a key step in the evolution of the manus and pectoral girdle in Ornithomimosauria.
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Affiliation(s)
- Elena Cuesta
- Institute of Dinosaur Research, Fukui Prefectural University, Kenjojima, Matsuoka, Eiheiji-Cho, 910-119, Fukui, Japan
- Bayerische Staatssammlung für Paläontologie und Geologie, Richard-Wagner-Straße 10, 80333 Munich, Germany
| | - Daniel Vidal
- Grupo de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional de Educación a Distancia, Paseo Senda del Rey 9, 28040 Madrid, Spain
| | - Francisco Ortega
- Grupo de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional de Educación a Distancia, Paseo Senda del Rey 9, 28040 Madrid, Spain
| | - Masateru Shibata
- Institute of Dinosaur Research, Fukui Prefectural University, Kenjojima, Matsuoka, Eiheiji-Cho, 910-119, Fukui, Japan
- Fukui Prefectural Dinosaur Museum, Muroko, Terao, Katsuyama, 911-8601, Fukui, Japan
| | - José L Sanz
- Real Academia de Ciencias Exactas, Fisicas y Naturales, Calle de Valverde, 24, 28004 Madrid, Spain
- Unidad de Paleontología, Departamento de Biología, Universidad Autónoma de Madrid, Calle Darwin, 2, 28049, Madrid, Spain
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8
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Funston GF, Chinzorig T, Tsogtbaatar K, Kobayashi Y, Sullivan C, Currie PJ. A new two-fingered dinosaur sheds light on the radiation of Oviraptorosauria. ROYAL SOCIETY OPEN SCIENCE 2020; 7:201184. [PMID: 33204472 PMCID: PMC7657903 DOI: 10.1098/rsos.201184] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 09/07/2020] [Indexed: 06/11/2023]
Abstract
Late Cretaceous trends in Asian dinosaur diversity are poorly understood, but recent discoveries have documented a radiation of oviraptorosaur theropods in China and Mongolia. However, little work has addressed the factors that facilitated this diversification. A new oviraptorid from the Late Cretaceous of Mongolia sheds light on the evolution of the forelimb, which appears to have played a role in the radiation of oviraptorosaurs. Surprisingly, the reduced arm has only two functional digits, highlighting a previously unrecognized occurrence of digit loss in theropods. Phylogenetic analysis shows that the onset of this reduction coincides with the radiation of heyuannine oviraptorids, following dispersal from southern China into the Gobi region. This suggests expansion into a new niche in the Gobi region, which relied less on the elongate, grasping forelimbs inherited by oviraptorosaurs. Variation in forelimb length and manus morphology provides another example of niche partitioning in oviraptorosaurs, which may have made possible their incredible diversity in the latest Cretaceous of Asia.
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Affiliation(s)
- Gregory F. Funston
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Tsogtbaatar Chinzorig
- Hokkaido University Museum, Hokkaido University, Sapporo, Japan
- Institute of Paleontology, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia
| | | | | | - Corwin Sullivan
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Philip J. Currie Dinosaur Museum, Wembley, Alberta, Canada
| | - Philip J. Currie
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
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9
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Norman DB. Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zool J Linn Soc 2020. [DOI: 10.1093/zoolinnean/zlaa061] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Abstract
A layer of keratinous scutes encased the skull of Scelidosaurus. The neurocranium and the associated principal sensory systems of this dinosaur are described. The cranial musculature is reconstructed and a subsequent functional analysis suggests that jaw motion was orthal, allowing pulping of vegetation and some high-angle shearing between opposing teeth. Wishboning of the lower jaw was enabled by transverse displacement of the quadrates, and the long-axis mandibular torsion that occurred during the chewing cycle was permitted by flexibility at the dentary symphysis. Limb proportions and pectoral and pelvic musculature reconstructions suggest that Scelidosaurus was a facultative quadruped of ‘average’ locomotor ability. It retained some anatomical features indicative of a bipedal-cursorial ancestry. Hindlimb motion was oblique-to-parasagittal to accommodate the girth of the abdomen. Scelidosaurus used a combination of costal and abdominally driven aspiration. The hypothesis that respiration was an ‘evolutionary driver’ of opisthopuby in all dinosaurs is overly simplistic. A critical assessment of datasets used to analyse the systematics of ornithischians (and thyreophoran subclades) has led to a revised dataset that positions Scelidosaurus as a stem ankylosaur, rather than a stem thyreophoran. The value of phylogenetic definitions is reconsidered in the light of the new thyreophoran cladogram.
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Affiliation(s)
- David B Norman
- Department of Earth Sciences, University of Cambridge, UK
- Christ’s College, St. Andrew’s Street, Cambridge, UK
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10
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Yang TR, Engler T, Lallensack JN, Samathi A, Makowska M, Schillinger B. Hatching Asynchrony in Oviraptorid Dinosaurs Sheds Light on Their Unique Nesting Biology. Integr Org Biol 2019; 1:obz030. [PMID: 33791544 PMCID: PMC7671163 DOI: 10.1093/iob/obz030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Dinosaur nesting biology has been an intriguing research topic, though dinosaur behaviors were relatively less illuminated because of the constraints of the fossil record. For instance, hatching asynchrony, where eggs in a single clutch hatch at different times, is unique to modern neoavian birds but was also suggested to be present in oviraptorid dinosaurs based on a possible partial clutch of four embryo-containing eggs from Mongolia. Unfortunately, unequivocal evidence for the origination of these eggs from a single clutch is lacking. Here we report a new, better preserved partial oviraptorid clutch with three embryo-containing eggs—a single egg (Egg I) and a pair (Egg II/III)—from the Late Cretaceous Nanxiong Group of Jiangxi Province, China. Geopetal features indicate that the pair of eggs was laid prior to the single egg. Neutron tomographic images in combination with osteological features indicate that the embryo of the single egg is less developed than those of the paired eggs. Eggshell histology suggests that the embryo-induced erosion in the paired eggs is markedly more pronounced than in the single egg, providing a new line of evidence for hatching asynchrony. The inferred hatching asynchrony in combination with previously surmised thermoregulatory incubation and communal nesting behaviors very likely suggests that oviraptorid dinosaurs presented a unique reproductive biology lacking modern analogs, which is contrary to the predominant view that their reproductive biology was intermediate between that of modern crocodiles and birds.
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Affiliation(s)
- T-R Yang
- Section of Paleontology, Institute of Geosciences, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 8, 53115 Bonn, Germany.,Division of Geology, National Museum of Natural Science, Guancian Road 1, 40453 Taichung, Taiwan
| | - T Engler
- Section of Paleontology, Institute of Geosciences, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 8, 53115 Bonn, Germany
| | - J N Lallensack
- Section of Paleontology, Institute of Geosciences, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 8, 53115 Bonn, Germany
| | - A Samathi
- Section of Paleontology, Institute of Geosciences, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 8, 53115 Bonn, Germany.,Biodiversity and Conservation Research Unit. Walai Rukhavej Botanical Research Institute, Mahasarakham University, 44150 Maha Sarakham, Thailand
| | - M Makowska
- Photons for Engineering and Manufacturing Group, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - B Schillinger
- Heinz Maier-Leibnitz Zentrum (MLZ), Lichtenbergstraße 1, 85748 Garching, Germany
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11
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Lee S, Lee YN, Chinsamy A, Lü J, Barsbold R, Tsogtbaatar K. A new baby oviraptorid dinosaur (Dinosauria: Theropoda) from the Upper Cretaceous Nemegt Formation of Mongolia. PLoS One 2019; 14:e0210867. [PMID: 30726228 PMCID: PMC6364893 DOI: 10.1371/journal.pone.0210867] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 01/03/2019] [Indexed: 11/18/2022] Open
Abstract
Recent discoveries of new oviraptorosaurs revealed their high diversity from the Cretaceous Period in Asia and North America. Particularly, at the family level, oviraptorids are among the most diverse theropod dinosaurs in the Late Cretaceous of Mongolia and China. A new oviraptorid dinosaur Gobiraptor minutus gen. et sp. nov. from the Upper Cretaceous Nemegt Formation is described here based on a single holotype specimen that includes incomplete cranial and postcranial elements. The most prominent characters of Gobiraptor are its thickened rostrodorsal end of the mandibular symphysis and a rudimentary lingual shelf on each side of the dentary. Each lingual shelf is lined with small occlusal foramina and demarcated by a weakly developed lingual ridge. This mandibular morphology of Gobiraptor is unique among oviraptorids and likely to be linked to a specialized diet that probably included hard materials, such as seeds or bivalves. The osteohistology of the femur of the holotype specimen indicates that the individual was fairly young at the time of its death. Phylogenetic analysis recovers Gobiraptor as a derived oviraptorid close to three taxa from the Ganzhou region in southern China, but rather distantly related to other Nemegt oviraptorids which, as the results of recent studies, are also not closely related to each other. Gobiraptor increases diversity of oviraptorids in the Nemegt Formation and its presence confirms the successful adaptation of oviraptorids to a mesic environment.
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Affiliation(s)
- Sungjin Lee
- School of Earth and Environmental Sciences, Seoul National University, Seoul, South Korea
| | - Yuong-Nam Lee
- School of Earth and Environmental Sciences, Seoul National University, Seoul, South Korea
| | - Anusuya Chinsamy
- Department of Biological Sciences, University of Cape Town, Cape Town, South Africa
| | - Junchang Lü
- Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China
| | - Rinchen Barsbold
- Institute of Paleontology and Geology, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia
| | - Khishigjav Tsogtbaatar
- Institute of Paleontology and Geology, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia
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