1
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Ezcurra MD. Exploring the effects of weighting against homoplasy in genealogies of palaeontological phylogenetic matrices. Cladistics 2024; 40:242-281. [PMID: 38728134 DOI: 10.1111/cla.12581] [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: 01/11/2024] [Revised: 04/15/2024] [Accepted: 04/16/2024] [Indexed: 05/12/2024] Open
Abstract
Although simulations have shown that implied weighting (IW) outperforms equal weighting (EW) in phylogenetic parsimony analyses, weighting against homoplasy lacks extensive usage in palaeontology. Iterative modifications of several phylogenetic matrices in the last decades resulted in extensive genealogies of datasets that allow the evaluation of differences in the stability of results for alternative character weighting methods directly on empirical data. Each generation was compared against the most recent generation in each genealogy because it is assumed that it is the most comprehensive (higher sampling), revised (fewer misscorings) and complete (lower amount of missing data) matrix of the genealogy. The analyses were conducted on six different genealogies under EW and IW and extended implied weighting (EIW) with a range of concavity constant values (k) between 3 and 30. Pairwise comparisons between trees were conducted using Robinson-Foulds distances normalized by the total number of groups, distortion coefficient, subtree pruning and regrafting moves, and the proportional sum of group dissimilarities. The results consistently show that IW and EIW produce results more similar to those of the last dataset than EW in the vast majority of genealogies and for all comparative measures. This is significant because almost all of these matrices were originally analysed only under EW. Implied weighting and EIW do not outperform each other unambiguously. Euclidean distances based on a principal components analysis of the comparative measures show that different ranges of k-values retrieve the most similar results to the last generation in different genealogies. There is a significant positive linear correlation between the optimal k-values and the number of terminals of the last generations. This could be employed to inform about the range of k-values to be used in phylogenetic analyses based on matrix size but with the caveat that this emergent relationship still relies on a low sample size of genealogies.
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Affiliation(s)
- Martín D Ezcurra
- Sección Paleontología de Vertebrados, CONICET-Museo Argentino de Ciencias Naturales, Ángel Gallardo 470, C1405DJR, Ciudad Autónoma de Buenos Aires, Argentina
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, B15 2TT, Birmingham, UK
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2
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Tse YT, Miller CV, Pittman M. Morphological disparity and structural performance of the dromaeosaurid skull informs ecology and evolutionary history. BMC Ecol Evol 2024; 24:39. [PMID: 38622512 PMCID: PMC11020771 DOI: 10.1186/s12862-024-02222-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 03/11/2024] [Indexed: 04/17/2024] Open
Abstract
Non-avialan theropod dinosaurs had diverse ecologies and varied skull morphologies. Previous studies of theropod cranial morphology mostly focused on higher-level taxa or characteristics associated with herbivory. To better understand morphological disparity and function within carnivorous theropod families, here we focus on the Dromaeosauridae, 'raptors' traditionally seen as agile carnivorous hunters.We applied 2D geometric morphometrics to quantify skull shape, performed mechanical advantage analysis to assess the efficiency of bite force transfer, and performed finite element analysis to examine strain distribution in the skull during biting. We find that dromaeosaurid skull morphology was less disparate than most non-avialan theropod groups. Their skulls show a continuum of form between those that are tall and short and those that are flat and long. We hypothesise that this narrower morphological disparity indicates developmental constraint on skull shape, as observed in some mammalian families. Mechanical advantage indicates that Dromaeosaurus albertensis and Deinonychus antirrhopus were adapted for relatively high bite forces, while Halszkaraptor escuilliei was adapted for high bite speed, and other dromaeosaurids for intermediate bite forces and speeds. Finite element analysis indicates regions of high strain are consistent within dromaeosaurid families but differ between them. Average strain levels do not follow any phylogenetic pattern, possibly due to ecological convergence between distantly-related taxa.Combining our new morphofunctional data with a re-evaluation of previous evidence, we find piscivorous reconstructions of Halszkaraptor escuilliei to be unlikely, and instead suggest an invertivorous diet and possible adaptations for feeding in murky water or other low-visibility conditions. We support Deinonychus antirrhopus as being adapted for taking large vertebrate prey, but we find that its skull is relatively less resistant to bite forces than other dromaeosaurids. Given the recovery of high bite force resistance for Velociraptor mongoliensis, which is believed to have regularly engaged in scavenging behaviour, we suggest that higher bite force resistance in a dromaeosaurid taxon may reflect a greater reliance on scavenging rather than fresh kills.Comparisons to the troodontid Gobivenator mongoliensis suggest that a gracile rostrum like that of Velociraptor mongoliensis is ancestral to their closest common ancestor (Deinonychosauria) and the robust rostra of Dromaeosaurus albertensis and Deinonychus antirrhopus are a derived condition. Gobivenator mongoliensis also displays a higher jaw mechanical advantage and lower resistance to bite force than the examined dromaeosaurids, but given the hypothesised ecological divergence of troodontids from dromaeosaurids it is unclear which group, if either, represents the ancestral condition. Future work extending sampling to troodontids would therefore be invaluable and provide much needed context to the origin of skull form and function in early birds. This study illustrates how skull shape and functional metrics can discern non-avialan theropod ecology at lower taxonomic levels and identify variants of carnivorous feeding.
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Affiliation(s)
- Yuen Ting Tse
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Case Vincent Miller
- Department of Earth Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Michael Pittman
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
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3
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Jasinski SE, Sullivan RM, Carter AM, Johnson EH, Dalman SG, Zariwala J, Currie PJ. Osteology and reassessment of Dineobellator notohesperus, a southern eudromaeosaur (Theropoda: Dromaeosauridae: Eudromaeosauria) from the latest Cretaceous of New Mexico. Anat Rec (Hoboken) 2023; 306:1712-1756. [PMID: 36342817 DOI: 10.1002/ar.25103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 09/11/2022] [Accepted: 09/30/2022] [Indexed: 11/09/2022]
Abstract
Dromaeosaurids (Theropoda: Dromaeosauridae), a group of dynamic, swift predators, have a sparse fossil record, particularly at the end of the Cretaceous Period. The recently described Dineobellator notohesperus, consisting of a partial skeleton from the Upper Cretaceous (Maastrichtian) of New Mexico, is the only diagnostic dromaeosaurid to be recovered from the latest Cretaceous of the southwestern United States. Reinterpreted and newly described material include several caudal vertebrae, portions of the right radius and pubis, and an additional ungual, tentatively inferred to be from manual digit III. Unique features, particularly those of the humerus, unguals, and caudal vertebrae, distinguish D. notohesperus from other known dromaeosaurids. This material indicates different physical attributes among dromaeosaurids, such as use of the forearms, strength in the hands and feet, and mobility of the tail. Several bones in the holotype exhibit abnormal growth and are inferred to be pathologic features resulting from an injury or disease. Similar lengths of the humerus imply Dineobellator and Deinonychus were of similar size, at least regarding length and/or height, although the more gracile nature of the humerus implies Dineobellator was a more lightly built predator. A new phylogenetic analysis recovers D. notohesperus as a dromaeosaurid outside other previously known and named clades. Theropod composition of the Naashoibito Member theropod fauna is like those found in the more northern Late Cretaceous North American ecosystems. Differences in tooth morphologies among recovered theropod teeth from the Naashoibito Member also implies D. notohesperus was not the only dromaeosaurid present in its environment.
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Affiliation(s)
- Steven E Jasinski
- Department of Environmental Science and Sustainability, Harrisburg University, Harrisburg, Pennsylvania, USA
- Don Sundquist Center of Excellence in Paleontology, Johnson City, Tennessee, USA
| | - Robert M Sullivan
- New Mexico Museum of Natural History and Science, Albuquerque, New Mexico, USA
| | - Aja M Carter
- Penn Engineering - GRASP Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Erynn H Johnson
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, USA
- Paleontological Research Institution, Ithaca, New York, USA
| | - Sebastian G Dalman
- New Mexico Museum of Natural History and Science, Albuquerque, New Mexico, USA
| | - Juned Zariwala
- Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, India
| | - Philip J Currie
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
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4
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Li Z, Wang M, Stidham TA, Zhou Z. Decoupling the skull and skeleton in a Cretaceous bird with unique appendicular morphologies. Nat Ecol Evol 2023; 7:20-31. [PMID: 36593291 DOI: 10.1038/s41559-022-01921-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 10/03/2022] [Indexed: 01/03/2023]
Abstract
The Cretaceous is a critical time interval that encompasses explosive diversifications of terrestrial vertebrates, particularly the period when the earliest-branching birds, after divergence from their theropod ancestors, evolved the characteristic avian Bauplan that led eventually to their global radiation. This early phylogenetic diversity is overwhelmed by the Ornithothoraces, consisting of the Enantiornithes and Ornithuromorpha, whose members evolved key derived features of crown birds. This disparity consequently circumscribes a large morphological gap between these derived clades and the oldest bird Archaeopteryx. The non-ornithothoracine pygostylians, with an intermediate phylogenetic position, are key to deciphering those evolutionary transformations, but progress in their study has been hampered by the limited diversity of known fossils. Here we report an Early Cetaceous non-ornithothoracine pygostylian, Cratonavis zhui gen. et sp. nov., that exhibits a unique combination of a non-avialan dinosaurian akinetic skull with an avialan post-cranial skeleton, revealing the key role of evolutionary mosaicism in early bird diversification. The unusually elongated scapular and metatarsal one preserved in Cratonavis highlights a breadth of skeletal plasticity, stemming from their distinct developmental modules and selection for possibly raptorial behaviour. Mapped changes in these two elements across theropod phylogeny demonstrate clade-specific evolutionary lability.
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Affiliation(s)
- Zhiheng Li
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.,Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, China
| | - Min Wang
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China. .,Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, China.
| | - Thomas A Stidham
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.,Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Zhonghe Zhou
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.,Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, China
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5
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Wang M, Stidham TA, O'Connor JK, Zhou Z. Insight into the evolutionary assemblage of cranial kinesis from a Cretaceous bird. eLife 2022; 11:e81337. [PMID: 36469022 PMCID: PMC9721616 DOI: 10.7554/elife.81337] [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: 06/23/2022] [Accepted: 11/28/2022] [Indexed: 12/07/2022] Open
Abstract
The independent movements and flexibility of various parts of the skull, called cranial kinesis, are an evolutionary innovation that is found in living vertebrates only in some squamates and crown birds and is considered to be a major factor underpinning much of the enormous phenotypic and ecological diversity of living birds, the most diverse group of extant amniotes. Compared to the postcranium, our understanding of the evolutionary assemblage of the characteristic modern bird skull has been hampered by sparse fossil records of early cranial materials, with competing hypotheses regarding the evolutionary development of cranial kinesis among early members of the avialans. Here, a detailed three-dimensional reconstruction of the skull of the Early Cretaceous enantiornithine Yuanchuavis kompsosoura allows for its in-depth description, including elements that are poorly known among early-diverging avialans but are central to deciphering the mosaic assembly of features required for modern avian cranial kinesis. Our reconstruction of the skull shows evolutionary and functional conservation of the temporal and palatal regions by retaining the ancestral theropod dinosaurian configuration within the skull of this otherwise derived and volant bird. Geometric morphometric analysis of the palatine suggests that loss of the jugal process represents the first step in the structural modifications of this element leading to the kinetic crown bird condition. The mixture of plesiomorphic temporal and palatal structures together with a derived avialan rostrum and postcranial skeleton encapsulated in Yuanchuavis manifests the key role of evolutionary mosaicism and experimentation in early bird diversification.
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Affiliation(s)
- Min Wang
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of SciencesBeijingChina
- Center for Excellence in Life and Paleoenvironment, Chinese Academy of SciencesBeijingChina
| | - Thomas A Stidham
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of SciencesBeijingChina
- Center for Excellence in Life and Paleoenvironment, Chinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | | | - Zhonghe Zhou
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of SciencesBeijingChina
- Center for Excellence in Life and Paleoenvironment, Chinese Academy of SciencesBeijingChina
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6
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Riguetti FJ, Apesteguía S, Pereda-Suberbiola X. A new Cretaceous thyreophoran from Patagonia supports a South American lineage of armoured dinosaurs. Sci Rep 2022; 12:11621. [PMID: 35953515 PMCID: PMC9372066 DOI: 10.1038/s41598-022-15535-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Accepted: 06/24/2022] [Indexed: 11/24/2022] Open
Abstract
The early evolution of thyreophoran dinosaurs is thought to have occurred primarily in northern continents since most evidence comes from the Lower and Middle Jurassic of Europe and North America. The diversification into stegosaurs and ankylosaurs is obscured by a patchy fossil record comprising only a handful of fragmentary fossils, most with uncertain phylogenetic affinities. Here we report the discovery of a new armoured dinosaur from the early Late Cretaceous of Argentina, recovered phylogenetically using various datasets either as a basal thyreophoran or a stem ankylosaur, closely related to Scelidosaurus. It bears unusual anatomical features showing that several traits traditionally associated with the heavy Cretaceous thyreophorans did not occur universally. Jakapil kaniukura gen. et sp. nov. is the first definitive thyreophoran species from the Argentinian Patagonia. Unlike most thyreophorans, it seems to show a bipedal stance, as in Scutellosaurus. Jakapil also shows that early thyreophorans had a much broader geographic distribution than previously thought. It is a member of an ancient basal thyreophoran lineage that survived until the Late Cretaceous in South America.
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Affiliation(s)
- Facundo J Riguetti
- Fundación de Historia Natural Félix de Azara, Centro de Ciencias Naturales Ambientales y Antropológicas, Universidad Maimónides, CONICET, Hidalgo 775, 7mo piso (1405), Buenos Aires, Argentina.
| | - Sebastián Apesteguía
- Fundación de Historia Natural Félix de Azara, Centro de Ciencias Naturales Ambientales y Antropológicas, Universidad Maimónides, CONICET, Hidalgo 775, 7mo piso (1405), Buenos Aires, Argentina
| | - Xabier Pereda-Suberbiola
- Departamento de Geología, Facultad de Ciencia y Tecnología, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Apartado 644, 48080, Bilbao, Spain
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7
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Napoli JG, Ruebenstahl AA, Bhullar BAS, Turner AH, Norell MA. A New Dromaeosaurid (Dinosauria: Coelurosauria) from Khulsan, Central Mongolia. AMERICAN MUSEUM NOVITATES 2021. [DOI: 10.1206/3982.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- James G. Napoli
- Richard Gilder Graduate School, American Museum of Natural History, New York
| | | | | | - Alan H. Turner
- Division of Paleontology, American Museum of Natural History, New York
| | - Mark A. Norell
- Richard Gilder Graduate School, American Museum of Natural History, New York
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8
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Wang S, Zhang Q, Tan Q, Jiangzuo Q, Zhang H, Tan L. New troodontid theropod specimen from Inner Mongolia, China clarifies phylogenetic relationships of later‐diverging small‐bodied troodontids and paravian body size evolution. Cladistics 2021; 38:59-82. [DOI: 10.1111/cla.12467] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/13/2021] [Indexed: 11/30/2022] Open
Affiliation(s)
- Shuo Wang
- Department of Pathology, Keck School of Medicine University of Southern California Los Angeles CA90033USA
| | - Qiyue Zhang
- College of Life Sciences Nankai University Tianjin300071China
| | - Qingwei Tan
- Long Hao Institute of Geology and Paleontology Hohhot Nei Mongol010010China
| | - Qigao Jiangzuo
- Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences Peking University 5 Yiheyuan Road Beijing100871China
| | - Huitao Zhang
- Beijing Advanced Innovation Center for Imaging Technology Capital Normal University Beijing100048China
| | - Lin Tan
- Long Hao Institute of Geology and Paleontology Hohhot Nei Mongol010010China
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9
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Wang M, Stidham TA, Li Z, Xu X, Zhou Z. Cretaceous bird with dinosaur skull sheds light on avian cranial evolution. Nat Commun 2021; 12:3890. [PMID: 34162868 PMCID: PMC8222284 DOI: 10.1038/s41467-021-24147-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 06/03/2021] [Indexed: 02/05/2023] Open
Abstract
The transformation of the bird skull from an ancestral akinetic, heavy, and toothed dinosaurian morphology to a highly derived, lightweight, edentulous, and kinetic skull is an innovation as significant as powered flight and feathers. Our understanding of evolutionary assembly of the modern form and function of avian cranium has been impeded by the rarity of early bird fossils with well-preserved skulls. Here, we describe a new enantiornithine bird from the Early Cretaceous of China that preserves a nearly complete skull including the palatal elements, exposing the components of cranial kinesis. Our three-dimensional reconstruction of the entire enantiornithine skull demonstrates that this bird has an akinetic skull indicated by the unexpected retention of the plesiomorphic dinosaurian palate and diapsid temporal configurations, capped with a derived avialan rostrum and cranial roof, highlighting the highly modular and mosaic evolution of the avialan skull.
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Affiliation(s)
- Min Wang
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.
- CAS Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, China.
| | - Thomas A Stidham
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhiheng Li
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, China
| | - Xing Xu
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, China
| | - Zhonghe Zhou
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, China
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10
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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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11
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Schroeder K, Lyons SK, Smith FA. The influence of juvenile dinosaurs on community structure and diversity. Science 2021; 371:941-944. [PMID: 33632845 DOI: 10.1126/science.abd9220] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 01/21/2021] [Indexed: 12/15/2022]
Abstract
Despite dominating biodiversity in the Mesozoic, dinosaurs were not speciose. Oviparity constrained even gigantic dinosaurs to less than 15 kg at birth; growth through multiple morphologies led to the consumption of different resources at each stage. Such disparity between neonates and adults could have influenced the structure and diversity of dinosaur communities. Here, we quantified this effect for 43 communities across 136 million years and seven continents. We found that megatheropods (more than 1000 kg) such as tyrannosaurs had specific effects on dinosaur community structure. Although herbivores spanned the body size range, communities with megatheropods lacked carnivores weighing 100 to 1000 kg. We demonstrate that juvenile megatheropods likely filled the mesocarnivore niche, resulting in reduced overall taxonomic diversity. The consistency of this pattern suggests that ontogenetic niche shift was an important factor in generating dinosaur community structure and diversity.
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Affiliation(s)
- Katlin Schroeder
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.
| | - S Kathleen Lyons
- School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA
| | - Felisa A Smith
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
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12
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Turner AH, Montanari S, Norell MA. A New Dromaeosaurid from the Late Cretaceous Khulsan Locality of Mongolia. AMERICAN MUSEUM NOVITATES 2021. [DOI: 10.1206/3965.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Alan H. Turner
- Division of Paleontology, American Museum of Natural History, New York, and Department of Anatomical Sciences, Stony Brook University, Stony Brook, New York
| | - Shaena Montanari
- Division of Paleontology, American Museum of Natural History, New York; currently Walter Cronkite School of Journalism and Mass Communication at Arizona State University, Phoenix Arizona
| | - Mark A. Norell
- Division of Paleontology, American Museum of Natural History, New York
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13
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Potential for Powered Flight Neared by Most Close Avialan Relatives, but Few Crossed Its Thresholds. Curr Biol 2020; 30:4033-4046.e8. [DOI: 10.1016/j.cub.2020.06.105] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 03/19/2020] [Accepted: 06/30/2020] [Indexed: 01/04/2023]
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14
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Chiarenza AA, Fiorillo AR, Tykoski RS, McCarthy PJ, Flaig PP, Contreras DL. The first juvenile dromaeosaurid (Dinosauria: Theropoda) from Arctic Alaska. PLoS One 2020; 15:e0235078. [PMID: 32639990 PMCID: PMC7343144 DOI: 10.1371/journal.pone.0235078] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 06/07/2020] [Indexed: 12/01/2022] Open
Abstract
Compared to the osteological record of herbivorous dinosaurs from the Late Cretaceous Prince Creek Formation of northern Alaska, there are relatively fewer remains of theropods. The theropod record from this unit is mostly comprised of isolated teeth, and the only non-dental remains known can be attributed to the troodontid cf. Troodon and the tyrannosaurid Nanuqsaurus. Thus far, the presence of members of Dromaeosauridae has been limited to isolated teeth. Here we describe a symphyseal portion of a small dentary with two ziphodont teeth. Based on tooth shape, denticle morphology, and the position of the Meckelian groove, we attribute this partial dentary to a saurornitholestine dromaeosaurid. The fibrous bone surface, small size, and higher number of mesial denticles compared to distal ones point to a juvenile growth stage for this individual. Multivariate comparison of theropod teeth morphospace by means of principal component analysis reveals an overlap between this dentary and Saurornitholestinae dromaeosaurid morphospace, a result supported by phylogenetic analyses. This is the first confirmed non-dental fossil specimen from a member of Dromaeosauridae in the Arctic, expanding on the role of Beringia as a dispersal route for this clade between Asia and North America. Furthermore, the juvenile nature of this individual adds to a growing body of data that suggests Cretaceous Arctic dinosaurs of Alaska did not undergo long-distance migration, but rather they were year-round residents of these paleopolar latitudes.
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Affiliation(s)
- Alfio Alessandro Chiarenza
- Imperial College London, London, United Kingdom
- University College London, London, United Kingdom
- * E-mail:
| | - Anthony R. Fiorillo
- Huffington Department of Earth Sciences, Southern Methodist University, Dallas, TX, United States of America
| | - Ronald S. Tykoski
- Perot Museum of Nature and Science, Dallas, TX, United States of America
| | - Paul J. McCarthy
- Department of Geosciences, University of Alaska, Fairbanks, AK, United States of America
| | - Peter P. Flaig
- Jackson School of Geosciences, Bureau of Economic Geology, University of Texas at Austin, Austin, TX, United States of America
| | - Dori L. Contreras
- Perot Museum of Nature and Science, Dallas, TX, United States of America
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15
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Brownstein CD. Dromaeosaurid crania demonstrate the progressive loss of facial pneumaticity in coelurosaurian dinosaurs. Zool J Linn Soc 2020. [DOI: 10.1093/zoolinnean/zlaa048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Dinosaurs are notable for their extensive skeletal pneumaticity, a feature that may have helped facilitate the development of various ‘extreme’ body plans in this group. Despite its relevance to understanding the evolution of the avian body plan, this feature has only been described in detail for a few non-avian dinosaurs, and cranial pneumaticity outside the braincase remains poorly documented. I describe facial pneumatic features in members of the Dromaeosauridae, a clade of hypercarnivorous dinosaurs closely allied to birds. Variation in the pneumaticity of the nasals and jugals, the position and shape of the pneumatic fenestrae of the maxilla and the border of the antorbital fossa shows that facial pneumaticity differed substantially among closely related dromaeosaurids and other bird-like dinosaurs. Ancestral state reconstructions of facial pneumaticity in coelurosaurs suggest a complex evolutionary history for these features. Surprisingly, the general trend along the path towards birds was the loss or reduction of superficial pneumatic features on the snout and cheek. Some facial pneumatic features seem to have evolved secondarily in some derived bird-like forms. The results show superficial facial pneumaticity did not increase in coelurosaurs and emphasize the complexity of the evolution of pneumatization in the lineage leading to birds.
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16
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Gianechini FA, Ercoli MD, Díaz-Martínez I. Differential locomotor and predatory strategies of Gondwanan and derived Laurasian dromaeosaurids (Dinosauria, Theropoda, Paraves): Inferences from morphometric and comparative anatomical studies. J Anat 2020; 236:772-797. [PMID: 32023660 DOI: 10.1111/joa.13153] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 12/02/2019] [Accepted: 12/20/2019] [Indexed: 11/29/2022] Open
Abstract
Tetrapod limbs morphology is a reliable proxy of locomotor capacities. Beyond this, other aspects of life habits, such as predation abilities, can also be relevant to determine main morphofunctional appendicular properties, which ultimately reflect a compromise between different factors of the biological role. Dromaeosauridae is a dinosaur clade belonging to Theropoda, a group of bipedal predators. Dromaeosaurids represent an interesting study case, in which the hindlimbs have been proposed to be involved in both locomotion and predation activity. A peculiar feature characterizing all dromaeosaurids is a modified second pedal digit, which is typically related to predation. This theropod group is closely related to birds and diversified during the Cretaceous Period, mainly in the Northern Hemisphere (Laurasia). However, a subclade of dromaeosaurids, the Unenlagiinae, was recently recognized for Gondwana. Nevertheless, there are morphological differences between derived Laurasian dromaeosaurids (eudromaeosaurs) and unenlagiines. Such differences are observed in the proportions between hindlimb bones and in the presence of a subarctometatarsalian condition in unenlagiines, which is mainly characterized by a proximally constricted metatarsal III. To evaluate the function of these divergent morphologies, we conducted morphometric analyses and comparisons of qualitative morphological aspects, encompassing unenlagiines, other dromaeosaurids, as well as taxa from other theropod groups, including extant birds. The former approach consisted of two phylogenetic principal component analyses, one based on the main measurements of the hindlimb, and the other focused on the lengths of the pedal phalanges. The first analysis drew the unenlagiines close to taxa with long tibiae, as well as long and slender metatarsi. Instead, eudromaeosaurs are closer to taxa with shorter tibiae, and shorter and wider metatarsi. The second analysis showed that eudromaeosaurs and unenlagiines have similar phalangeal proportions, including the elongation of distal phalanges. However, the shorter second phalanx of the pedal digit II of eudromaeosaurs could have increased the force generated by this digit, which was the main predatory tool of the autopodium. This, together with a shorter and wider metatarsus, and a marked hinge-like morphology of the articular surfaces of metatarsals and phalanges, possibly allowed eudromaeosaurs to exert a great gripping strength and hunt large prey. Conversely, the longer and slender subarctometatarsus, and less well-marked hinge joints of unenlagiines possibly gave them greater cursorial capacities. Additionally, the longer second phalanx of digit II allowed unenlagiines fast movements of this digit to hunt smaller and elusive prey. Thus, the distinctive morphological evolutionary pathways of these two dromaeosaurid clades seem to have been influenced by the particular locomotor and predatory specializations that characterized each of these lineages.
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Affiliation(s)
- Federico A Gianechini
- Instituto Multidisciplinario de Investigaciones Biológicas (IMIBIO), CONICET-Universidad Nacional de San Luis, Ciudad de San Luis, Argentina
| | - Marcos D Ercoli
- Instituto de Ecorregiones Andinas (INECOA), Universidad Nacional de Jujuy-CONICET, IdGyM, San Salvador de Jujuy, Argentina
| | - Ignacio Díaz-Martínez
- Instituto de Investigación en Paleobiologia y Geología (IIPG), CONICET-Universidad Nacional de Río Negro, General Roca, Argentina
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17
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Brownstein CD. Halszkaraptor escuilliei and the evolution of the paravian bauplan. Sci Rep 2019; 9:16455. [PMID: 31712644 PMCID: PMC6848195 DOI: 10.1038/s41598-019-52867-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 10/24/2019] [Indexed: 01/03/2023] Open
Abstract
The evolution of birds from dinosaurs is a subject that has received great attention among vertebrate paleontologists. Nevertheless, the early evolution of the paravians, the group that contains birds and their closest non-avian dinosaur relatives, remains very poorly known. Even the most basal members of one paravian lineage, the Dromaeosauridae, already show a body plan that differs substantially from their closest non-paravian relatives. Recently, the dromaeosaurid Halszkaraptor escuilliei was described from the Cretaceous of Mongolia. Halszkaraptor possesses numerous unserrated premaxillary teeth, a platyrostral rostrum with a developed neurovascular system, an elongate neck, bizarrely-proportioned forearms, and a foreword-shifted center of mass, differing markedly from other paravians. A reevaluation of the anatomy, taphonomy, environmental setting, and phylogenetic position of H. escuilliei based on additional comparisons with other maniraptorans suggests that, rather than indicating it was a semiaquatic piscivore, the body plan of this dinosaur bears features widely distributed among maniraptorans and in some cases intermediate between the conditions in dromaeosaurids and related clades. I find no evidence for a semiaquatic lifestyle in Halszkaraptor. A phylogenetic reevaluation of Halszkaraptorinae places it as the sister clade to Unenlagiinae, indicating the bizarre features of unenlagiines previously interpreted as evidence of piscivory may also represent a mosaic of plesiomorphic, derived, and intermediate features. The anatomy of Halszkaraptor reveals that dromaeosaurids still possessed many features found in more basal maniraptoran and coelurosaur clades, including some that may have been tied to herbivory. Rather than being a semiaquatic piscavore, Halszkaraptor was a basal dromaeosaurid showing transitional features.
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Affiliation(s)
- Chase D Brownstein
- Research Associate, Dept. of Collections & Exhibitions, Stamford Museum and Nature Center, Stamford, USA.
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18
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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] [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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19
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Currie PJ, Evans DC. Cranial Anatomy of New Specimens of
Saurornitholestes langstoni
(Dinosauria, Theropoda, Dromaeosauridae) from the Dinosaur Park Formation (Campanian) of Alberta. Anat Rec (Hoboken) 2019; 303:691-715. [DOI: 10.1002/ar.24241] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 05/10/2019] [Accepted: 06/24/2019] [Indexed: 11/06/2022]
Affiliation(s)
- Philip J. Currie
- Department of Biological SciencesUniversity of Alberta Edmonton Alberta Canada
| | - David C. Evans
- Department of Natural History (Palaeobiology)Royal Ontario Museum Toronto Ontario Canada
- Department of Ecology and Evolutionary BiologyUniversity of Toronto Toronto Ontario Canada
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20
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Averianov A, Ivantsov S, Skutschas P. Theropod teeth from the Lower Cretaceous Ilek Formation of Western Siberia, Russia. ACTA ACUST UNITED AC 2019. [DOI: 10.31610/trudyzin/2019.323.2.65] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A sample of 136 isolated theropod teeth from nine vertebrate localities within the Lower Cretaceous (Barremian-Aptian) Ilek Formation in West Siberia, Russia, can be separated into five dental morphotypes referred to five оr six theropod taxa based on morphological characters. The Morphotype A includes small to large lateral teeth with relatively large distal denticles and smaller mesial denticles. Some of these teeth can be attributed to the Dromaeosauridae, while other teeth may belong to a basal member of the Tyrannosauroidea. The distinctly smaller lateral teeth referred to the Morphotype B are similar with Morphotype A in most respects but differ in the lack of mesial denticles and mesial carina, or having a lingually displaced mesial carina. These teeth may belong to juvenile individuals of the same dromaeosaurid taxon. The teeth belonging to Morphotype C also lack mesial denticles and differ from Morphotype B by a flattened area on the lingual side, which is also often present on the labial side. These teeth may belong to either Troodontidae or Microraptorinae, or to both groups. The mesial and lateral teeth of Morphotype E are characterized by unserrated mesial and distal carinae. These teeth most likely belong to a distinct taxon of Troodontidae with unserrated dentition. The teeth of the Morphotype D include mesial teeth with the mesial carina displaced lingually at various extent and denticles present on both carinae. The teeth with moderately displaced lingual carina can be referred to the same dromaeosaurid taxon, which lateral teeth represented by Morphotype A. The teeth with more displaced mesial carina and deeply U-shaped basal crown section belong to an indeterminate Tyrannosauroidea.
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Affiliation(s)
- A.O. Averianov
- Zoological Institute of the Russian Academy of Sciences, Universitetskaya Emb. 1, 199034 Saint Petersburg, Russia; Institute of Geology and Petroleum Technology, Kazan Federal University, Kremlevskaya Str. 4/5, 420008 Kazan, Russia; Borissiak Paleontological Institute of the Russian Academy of Sciences, Profsouznaya Str. 123, 117997 Moscow, Russia
| | - S.V. Ivantsov
- Laboratory of Mesozoic and Cenozoic Continental Ecosystems, Tomsk State University, Lenina Pr. 36, 634050 Tomsk, Russia
| | - P.P. Skutschas
- Vertebrate Zoology Department, Saint Petersburg State University, Universitetskaya Emb. 7/9, 199034 Saint Petersburg, Russia
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21
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Dinosaur ossification centres in embryonic birds uncover developmental evolution of the skull. Nat Ecol Evol 2018; 2:1966-1973. [DOI: 10.1038/s41559-018-0713-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 10/05/2018] [Indexed: 01/15/2023]
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22
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Xu X, Choiniere J, Tan Q, Benson RBJ, Clark J, Sullivan C, Zhao Q, Han F, Ma Q, He Y, Wang S, Xing H, Tan L. Two Early Cretaceous Fossils Document Transitional Stages in Alvarezsaurian Dinosaur Evolution. Curr Biol 2018; 28:2853-2860.e3. [PMID: 30146153 DOI: 10.1016/j.cub.2018.07.057] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 06/04/2018] [Accepted: 07/24/2018] [Indexed: 10/28/2022]
Abstract
Highly specialized animals are often difficult to place phylogenetically. The Late Cretaceous members of Alvarezsauria represent such an example, having been posited as members of various theropod lineages, including birds [1-11]. A 70-million-year ghost lineage exists between them and the Late Jurassic putative alvarezsaurian Haplocheirus [12], which preserves so few derived features that its membership in Alvarezsauria has recently been questioned [13]. If Haplocheirus is indeed an alvarezsaurian, then the 70-million-year gap between Haplocheirus and other alvarezsaurians represents the longest temporal hiatus within the fossil record of any theropod subgroup [14]. Here we report two new alvarezsaurians from the Early Cretaceous of Western China that document successive, transitional stages in alvarezsaurian evolution. They provide further support for Haplocheirus as an alvarezsaurian and for alvarezsaurians as basal maniraptorans. Furthermore, they suggest that the early biogeographic history of the Alvarezsauria involved dispersals from Asia to other continents. The new specimens are temporally, morphologically, and functionally intermediate between Haplocheirus and other known alvarezsaurians and provide a striking example of the evolutionary transition from a typical theropod forelimb configuration (i.e., the relatively long arm and three-digit grasping hand of typical tetanuran form in early-branching alvarezsaurians) to a highly specialized one (i.e., the highly modified and shortened arm and one-digit digging hand of Late Cretaceous parvicursorines such as Linhenykus [1, 15]). Comprehensive analyses incorporating data from these new finds show that the specialized alvarezsaurian forelimb morphology evolved slowly and in a mosaic fashion during the Cretaceous.
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Affiliation(s)
- Xing Xu
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 142 Xiwai Street, Beijing 100044, China; CAS Center for Excellence in Life and Paleoenvironment, 142 Xiwai Street, Beijing 100044, China; Centre for Research and Education on Biological Evolution and Environment, 163 Xianlin Road, Nanjing University, Nanjing 210045, China.
| | - Jonah Choiniere
- Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050, South Africa; Department of Vertebrate Paleontology and Richard Gilder Graduate School, American Museum of Natural History, Central Park West at 79(th) Street, New York, NY 10024, USA
| | - Qingwei Tan
- Long Hao Institute of Geology and Paleontology, Jia 29, Fengzhou Road, Hohhot, Nei Mongol 010010, China
| | - Roger B J Benson
- Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Johannesburg WITS 2050, South Africa; Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
| | - James Clark
- Department of Biological Sciences, George Washington University, 2023 G Street NW, Washington, DC 20052, USA; Centre for Vertebrate Evolutionary Biology, Yunnan University, 2 Green Lake North Road, Kunming 650091, China
| | - Corwin Sullivan
- Department of Biological Sciences, University of Alberta, 11455 Saskatchewan Drive, Edmonton, AB T6G 2E9, Canada; Philip J. Currie Dinosaur Museum, 9301 112 Avenue, Wembley, AB T0H 3S0, Canada
| | - Qi Zhao
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 142 Xiwai Street, Beijing 100044, China
| | - Fenglu Han
- School of Earth Sciences, China University of Geosciences, 388 Lumo Road, Wuhan 430074, China
| | - Qingyu Ma
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 142 Xiwai Street, Beijing 100044, China
| | - Yiming He
- School of Earth Sciences and Engineering, Nanjing University, 163 Xianlin Road, Nanjing 210045, China
| | - Shuo Wang
- College of Life Science, Capital Normal Univerity, 105 West 3(rd) Ring Road North, Beijing 100048, China
| | - Hai Xing
- Beijing Museum of Natural History, Beijing Academy of Science and Technology, 126 South Tianqiao Street, Beijing 100050, China
| | - Lin Tan
- Long Hao Institute of Geology and Paleontology, Jia 29, Fengzhou Road, Hohhot, Nei Mongol 010010, China
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Yin YL, Pei R, Zhou CF. Cranial morphology of Sinovenator changii (Theropoda: Troodontidae) on the new material from the Yixian Formation of western Liaoning, China. PeerJ 2018; 6:e4977. [PMID: 29942679 PMCID: PMC6015489 DOI: 10.7717/peerj.4977] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 05/24/2018] [Indexed: 11/20/2022] Open
Abstract
A new three-dimensionally preserved troodontid specimen consisting of most of the skull, partial mandibles and six articulated cervical vertebrae (PMOL-AD00102) from the Early Cretaceous Yixian Formation of Beipiao, western Liaoning, China is identified as Sinovenator changii on the basis of a surangular with a “T”-shaped cross-section. High-resolution computed tomographic data for the skull of this new specimen facilitated a detailed description of the cranial anatomy of S. changii. New diagnostic features of S. changii include a well-developed medial shelf on the jugal, a slender bar in the parasphenoid recess, a lateral groove on the pterygoid flange of the ectopterygoid, and the lateral surface of the anterior cervical vertebrae bearing two pneumatic foramina. Our new observation confirms that the braincase of Sinovenator is not as primitive as previously suggested, although it still shows an intermediate state between derived troodontids and non-troodontid paravians in having an initial stage of the subotic recess and the otosphenoidal crest. Additionally, this new specimen reveals some novel and valuable anatomical information of troodontids regarding the quadrate-quadratojugal articulation, the stapes, the epipterygoid and the atlantal ribs.
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Affiliation(s)
- Ya-Lei Yin
- Paleontological Institute, Shenyang Normal University, Shenyang, Liaoning, China
| | - Rui Pei
- Department of Earth Sciences, the University of Hong Kong, Hong Kong, China
| | - Chang-Fu Zhou
- College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao, Shandong, China
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24
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Cau A, Madzia D. Redescription and affinities of Hulsanpes perlei (Dinosauria, Theropoda) from the Upper Cretaceous of Mongolia. PeerJ 2018; 6:e4868. [PMID: 29868277 PMCID: PMC5978397 DOI: 10.7717/peerj.4868] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 05/09/2018] [Indexed: 11/20/2022] Open
Abstract
Hulsanpes perlei is an enigmatic theropod dinosaur from the Baruungoyot Formation (?mid- to upper Campanian, Upper Cretaceous) of Mongolia. It was discovered in 1970, during the third Polish-Mongolian paleontological expedition to the Nemegt Basin. The taxon is known based on a partial braincase and an incomplete right hindlimb. However, the braincase fragment has never been described nor illustrated. We redescribe all elements that form the holotype of Hulsanpes and discuss the affinities of this taxon. The braincase fragment is interpreted as belonging to the inner ear region, and includes the floccular recess and part of the labyrinth. Hulsanpes perlei is confirmed as a valid taxon, diagnosed by a unique combination of metatarsal characters, including two autapomorphies. Historically, it represents the oldest record of the recently-established clade Halszkaraptorinae. Our findings identify subcursorial adaptations for Hulsanpes, shared with Mahakala, and differentiating them from Halszkaraptor. As such, appendicular disparity in the potentially sympatric halszkaraptorines suggest a reduced ecological overlap among these taxa, which may explain the co-occurrence of multiple species of this clade during the latest Cretaceous in what is now the Nemegt Basin.
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Affiliation(s)
- Andrea Cau
- Geological and Palaeontological Museum "G. Capellini", Bologna, Italy
| | - Daniel Madzia
- Institute of Paleobiology, Polish Academy of Sciences, Warsaw, Poland
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25
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Gianechini FA, Makovicky PJ, Apesteguía S, Cerda I. Postcranial skeletal anatomy of the holotype and referred specimens of Buitreraptor gonzalezorum Makovicky, Apesteguía and Agnolín 2005 (Theropoda, Dromaeosauridae), from the Late Cretaceous of Patagonia. PeerJ 2018; 6:e4558. [PMID: 29607264 PMCID: PMC5875404 DOI: 10.7717/peerj.4558] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 03/09/2018] [Indexed: 11/20/2022] Open
Abstract
Here we provide a detailed description of the postcranial skeleton of the holotype and referred specimens of Buitreraptor gonzalezorum. This taxon was recovered as an unenlagiine dromaeosaurid in several recent phylogenetic studies and is the best represented Gondwanan dromaeosaurid discovered to date. It was preliminarily described in a brief article, but a detailed account of its osteology is emerging in recent works. The holotype is the most complete specimen yet found, so an exhaustive description of it provides much valuable anatomical information. The holotype and referred specimens preserve the axial skeleton, pectoral and pelvic girdles, and both fore- and hindlimbs. Diagnostic postcranial characters of this taxon include: anterior cervical centra exceeding the posterior limit of neural arch; eighth and ninth cervical vertebral centra with lateroventral tubercles; pneumatic foramina only in anteriormost dorsals; middle and posterior caudal centra with a complex of shallow ridges on lateral surfaces; pneumatic furcula with two pneumatic foramina on the ventral surface; scapular blade transversely expanded at mid-length; well-projected flexor process on distal end of the humerus; dorsal rim of the ilium laterally everted; and concave dorsal rim of the postacetabular iliac blade. A paleohistological study of limb bones shows that the holotype represents an earlier ontogenetic stage than one of the referred specimens (MPCA 238), which correlates with the fusion of the last sacral vertebra to the rest of the sacrum in MPCA 238. A revised phylogenetic analysis recovered Buitreraptor as an unenlagiine dromaeosaurid, in agreement with previous works. The phylogenetic implications of the unenlagiine synapomorphies and other characters, such as the specialized pedal digit II and the distal ginglymus on metatarsal II, are discussed within the evolutionary framework of Paraves.
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Affiliation(s)
- Federico A Gianechini
- Instituto Multidisciplinario de Investigaciones Biológicas (IMIBIO-SL), CONICET-Universidad Nacional de San Luis, San Luis, Argentina
| | - Peter J Makovicky
- Section of Earth Sciences, Integrative Research Center, Field Museum of Natural History, Chicago, IL, USA
| | - Sebastián Apesteguía
- CONICET, Fundación de Historia Natural 'Félix de Azara', CEBBAD, Universidad Maimónides, Buenos Aires, Argentina
| | - Ignacio Cerda
- CONICET, Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro, General Roca, Río Negro, Argentina
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Rauhut OWM, Foth C, Tischlinger H. The oldest Archaeopteryx (Theropoda: Avialiae): a new specimen from the Kimmeridgian/Tithonian boundary of Schamhaupten, Bavaria. PeerJ 2018; 6:e4191. [PMID: 29383285 PMCID: PMC5788062 DOI: 10.7717/peerj.4191] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 12/04/2017] [Indexed: 11/25/2022] Open
Abstract
The iconic primeval bird Archaeopteryx was so far mainly known from the Altmühltal Formation (early Tithonian) of Bavaria, southern Germany, with one specimen having been found in the overlying Mörnsheim Formation. A new specimen (the 12th skeletal specimen) from the earliest Tithonian Painten Formation of Schamhaupten (Bavaria) represents the so far oldest representative of the genus. The new specimen shows several interesting anatomical details, including the presence of a postorbital in contact with the jugal, the presence of a separate prefrontal and coronoid, and opisthocoelous mid-cervical vertebrae. Based on observations on the new specimen, we discuss several problematic issues concerning Archaeopteryx, including the monophyly and diagnosis of the genus, the absence/presence of the sternum, the position of the gastralia, and variation in morphometrics and dental morphology in that genus. Based on a new diagnosis for the genus Archaeopteryx, the Berlin, Eichstätt, Solnhofen, Munich, Daiting, Thermopolis, 11th, and 12th specimens can be referred to this genus with high certainty. The Maxberg specimen is very probably also an Archaeopteryx, based on overall similarity, although none of the diagnostic characters can be evaluated with certainty. The ninth specimen (‘chicken wing’) might be Archaeopteryx, but cannot be referred to the genus with any certainty. In comparison with other paravians, the presence of distally thickened anterior pectoral ribs indicates that a rather large cartilagenous sternum was present in this taxon. In contrast to non-opisthopubic theropods, opisthopubic taxa, such as Archaeopteryx and many other paravians, have the posterior end of the gastral basket preserved at about half-length of the pubis, which might reflect the post-mortem collapse of enlarged abdominal air sacs in these taxa. Specimens that can be referred to Archaeopteryx show a high amount of variation, both in the morphometrics of the limb bones as well as in the dentition. In respect to the latter aspect, variation is found in tooth number, spacing, orientation, and morphology, with no two specimens showing the exact same pattern. The significance of this variation is unclear, and possible explanations reach from high intraspecific (and possibly ontogenetic and/or sexual dimorphic) variation to the possibility that the known specimens represent a ‘species flock’ of Archaeopteryx, possibly due to island speciation after the initial dispersal of the genus into the Solnhofen Archipelago.
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Affiliation(s)
- Oliver W M Rauhut
- SNSB-Bayerische Staatssammlung für Paläontologie und Geologie, Munich, Germany.,Department of Earth and Environmental Sciences, Ludwig-Maximilians University, Munich, Germany.,GeoBioCenter, Ludwig-Maximilians University, Munich, Germany
| | - Christian Foth
- Department of Geosciences, Université de Fribourg, Fribourg, Switzerland.,Staatliches Museum für Naturkunde, Stuttgart, Germany
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Pei R, Norell MA, Barta DE, Bever G, Pittman M, Xu X. Osteology of a New Late Cretaceous Troodontid Specimen from Ukhaa Tolgod, Ömnögovi Aimag, Mongolia. AMERICAN MUSEUM NOVITATES 2017. [DOI: 10.1206/3889.1] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Rui Pei
- Department of Earth Sciences, the University of Hong Kong, and Division of Paleontology, American Museum of Natural History, New York
| | - Mark A. Norell
- Macaulay Family Curator, Division of Paleontology, American Museum of Natural History, New York
| | - Daniel E. Barta
- Richard Gilder Graduate School and Division of Paleontology, American Museum of Natural History, New York
| | - G.S. Bever
- Division of Paleontology, American Museum of Natural History, New York, and Center for Functional Anatomy & Evolution, Johns Hopkins University School of Medicine, Baltimore
| | - Michael Pittman
- Vertebrate Palaeontology Laboratory, Department of Earth Sciences, the University of Hong Kong
| | - Xing Xu
- Institute of Vertebrate Paleontology and Paleoanthropology, the Chinese Academy of Sciences, Beijing
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Pritchard AC, Nesbitt SJ. A bird-like skull in a Triassic diapsid reptile increases heterogeneity of the morphological and phylogenetic radiation of Diapsida. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170499. [PMID: 29134065 PMCID: PMC5666248 DOI: 10.1098/rsos.170499] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 09/05/2017] [Indexed: 06/07/2023]
Abstract
The Triassic Period saw the first appearance of numerous amniote lineages (e.g. Lepidosauria, Archosauria, Mammalia) that defined Mesozoic ecosystems following the end Permian Mass Extinction, as well as the first major morphological diversification of crown-group reptiles. Unfortunately, much of our understanding of this event comes from the record of large-bodied reptiles (total body length > 1 m). Here we present a new species of drepanosaurid (small-bodied, chameleon-like diapsids) from the Upper Triassic Chinle Formation of New Mexico. Using reconstructions of micro-computed tomography data, we reveal the three-dimensional skull osteology of this clade for the first time. The skull presents many archaic anatomical traits unknown in Triassic crown-group reptiles (e.g. absence of bony support for the external ear), whereas other traits (e.g. toothless rostrum, anteriorly directed orbits, inflated endocranium) resemble derived avian theropods. A phylogenetic analysis of Permo-Triassic diapsids supports the hypothesis that drepanosaurs are an archaic lineage that originated in the Permian, far removed from crown-group Reptilia. The phylogenetic position of drepanosaurids indicates the presence of archaic Permian clades among Triassic small reptile assemblages and that morphological convergence produced a remarkably bird-like skull nearly 100 Myr before one is known to have emerged in Theropoda.
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Affiliation(s)
- Adam C. Pritchard
- Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794, USA
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06520-8109, USA
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Pei R, Li Q, Meng Q, Norell MA, Gao KQ. New Specimens ofAnchiornis huxleyi(Theropoda: Paraves) from the Late Jurassic of Northeastern China. BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY 2017. [DOI: 10.1206/0003-0090-411.1.1] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Rui Pei
- Department of Earth Sciences, the University of Hong Kong, Hong Kong; Division of Paleontology, American Museum of Natural History
| | - Quanguo Li
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing
| | | | - Mark A. Norell
- Division of Paleontology, American Museum of Natural History
| | - Ke-Qin Gao
- School of Earth and Space Sciences, Peking University, Beijing
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30
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Wang M, Hu H. A Comparative Morphological Study of the Jugal and Quadratojugal in Early Birds and Their Dinosaurian Relatives. Anat Rec (Hoboken) 2016; 300:62-75. [DOI: 10.1002/ar.23446] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/03/2016] [Accepted: 03/23/2016] [Indexed: 11/11/2022]
Affiliation(s)
- Min Wang
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences; Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences; Beijing China
- State Key Laboratory of Palaeobiology and Stratigraphy; Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences; Nanjing China
| | - Han Hu
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences; Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences; Beijing China
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31
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A bizarre theropod from the Early Cretaceous of Japan highlighting mosaic evolution among coelurosaurians. Sci Rep 2016; 6:20478. [PMID: 26908367 PMCID: PMC4763874 DOI: 10.1038/srep20478] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 01/05/2016] [Indexed: 11/12/2022] Open
Abstract
Our understanding of coelurosaurian evolution, particularly of bird origins, has been greatly improved, mainly due to numerous recently discovered fossils worldwide. Nearly all these discoveries are referable to the previously known coelurosaurian subgroups. Here, we report a new theropod, Fukuivenator paradoxus, gen. et sp. nov., based on a nearly complete specimen from the Lower Cretaceous Kitadani Formation of the Tetori Group, Fukui, Japan. While Fukuivenator possesses a large number of morphological features unknown in any other theropod, it has a combination of primitive and derived features seen in different theropod subgroups, notably dromaeosaurid dinosaurs. Computed-tomography data indicate that Fukuivenator possesses inner ears whose morphology is intermediate between those of birds and non-avian dinosaurs. Our phylogenetic analysis recovers Fukuivenator as a basally branching maniraptoran theropod, yet is unable to refer it to any known coelurosaurian subgroups. The discovery of Fukuivenator considerably increases the morphological disparity of coelurosaurian dinosaurs and highlights the high levels of homoplasy in coelurosaurian evolution.
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Foth C, Hedrick BP, Ezcurra MD. Cranial ontogenetic variation in early saurischians and the role of heterochrony in the diversification of predatory dinosaurs. PeerJ 2016; 4:e1589. [PMID: 26839749 PMCID: PMC4734445 DOI: 10.7717/peerj.1589] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 12/21/2015] [Indexed: 11/30/2022] Open
Abstract
Non-avian saurischian skulls underwent at least 165 million years of evolution and shapes varied from elongated skulls, such as in the theropod Coelophysis, to short and box-shaped skulls, such as in the sauropod Camarasaurus. A number of factors have long been considered to drive skull shape, including phylogeny, dietary preferences and functional constraints. However, heterochrony is increasingly being recognized as an important factor in dinosaur evolution. In order to quantitatively analyse the impact of heterochrony on saurischian skull shape, we analysed five ontogenetic trajectories using two-dimensional geometric morphometrics in a phylogenetic framework. This allowed for the comparative investigation of main ontogenetic shape changes and the evaluation of how heterochrony affected skull shape through both ontogenetic and phylogenetic trajectories. Using principal component analyses and multivariate regressions, it was possible to quantify different ontogenetic trajectories and evaluate them for evidence of heterochronic events allowing testing of previous hypotheses on cranial heterochrony in saurischians. We found that the skull shape of the hypothetical ancestor of Saurischia likely led to basal Sauropodomorpha through paedomorphosis, and to basal Theropoda mainly through peramorphosis. Paedomorphosis then led from Orionides to Avetheropoda, indicating that the paedomorphic trend found by previous authors in advanced coelurosaurs may extend back into the early evolution of Avetheropoda. Not only are changes in saurischian skull shape complex due to the large number of factors that affected it, but heterochrony itself is complex, with a number of possible reversals throughout non-avian saurischian evolution. In general, the sampling of complete ontogenetic trajectories including early juveniles is considerably lower than the sampling of single adult or subadult individuals, which is a major impediment to the study of heterochrony on non-avian dinosaurs. Thus, the current work represents an exploratory analysis. To better understand the cranial ontogeny and the impact of heterochrony on skull evolution in saurischians, the data set that we present here must be expanded and complemented with further sampling from future fossil discoveries, especially of juvenile individuals.
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Affiliation(s)
- Christian Foth
- SNSB, Bayerische Staatssammlung für Paläontologie und Geologie, München, Germany; Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität, München, Germany; Department of Geosciences, University of Fribourg/Freiburg, Fribourg, Switzerland
| | - Brandon P Hedrick
- Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA, United States; Department of Biology, University of Massachusetts, Amherst, MA, United States
| | - Martin D Ezcurra
- Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität, München, Germany; CONICET, Sección Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales, Buenos Aires, Argentina; School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
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Hendrickx C, Mateus O, Buffetaut E. Morphofunctional Analysis of the Quadrate of Spinosauridae (Dinosauria: Theropoda) and the Presence of Spinosaurus and a Second Spinosaurine Taxon in the Cenomanian of North Africa. PLoS One 2016; 11:e0144695. [PMID: 26734729 PMCID: PMC4703214 DOI: 10.1371/journal.pone.0144695] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 11/20/2015] [Indexed: 11/30/2022] Open
Abstract
Six quadrate bones, of which two almost certainly come from the Kem Kem beds (Cenomanian, Upper Cretaceous) of south-eastern Morocco, are determined to be from juvenile and adult individuals of Spinosaurinae based on phylogenetic, geometric morphometric, and phylogenetic morphometric analyses. Their morphology indicates two morphotypes evidencing the presence of two spinosaurine taxa ascribed to Spinosaurus aegyptiacus and? Sigilmassasaurus brevicollis in the Cenomanian of North Africa, casting doubt on the accuracy of some recent skeletal reconstructions which may be based on elements from several distinct species. Morphofunctional analysis of the mandibular articulation of the quadrate has shown that the jaw mechanics was peculiar in Spinosauridae. In mature spinosaurids, the posterior parts of the two mandibular rami displaced laterally when the jaw was depressed due to a lateromedially oriented intercondylar sulcus of the quadrate. Such lateral movement of the mandibular ramus was possible due to a movable mandibular symphysis in spinosaurids, allowing the pharynx to be widened. Similar jaw mechanics also occur in some pterosaurs and living pelecanids which are both adapted to capture and swallow large prey items. Spinosauridae, which were engaged, at least partially, in a piscivorous lifestyle, were able to consume large fish and may have occasionally fed on other prey such as pterosaurs and juvenile dinosaurs.
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Affiliation(s)
- Christophe Hendrickx
- GeoBioTec, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
- Museu da Lourinhã, Lourinhã, Portugal
- * E-mail:
| | - Octávio Mateus
- GeoBioTec, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
- Museu da Lourinhã, Lourinhã, Portugal
| | - Eric Buffetaut
- CNRS (UMR 8538), Laboratoire de Géologie de l’École Normale Supérieure, PSL Research University, Paris, France
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Wang M, Zhou Z, Zhou S. A new basal ornithuromorph bird (Aves: Ornithothoraces) from the Early Cretaceous of China with implication for morphology of early Ornithuromorpha. Zool J Linn Soc 2016. [DOI: 10.1111/zoj.12302] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Min Wang
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences; Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences; 142 Xizhimenwai Street Beijing 100044 China
| | - Zhonghe Zhou
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences; Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences; 142 Xizhimenwai Street Beijing 100044 China
| | - Shuang Zhou
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences; Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences; 142 Xizhimenwai Street Beijing 100044 China
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Hendrickx C, Araújo R, Mateus O. The non-avian theropod quadrate I: standardized terminology with an overview of the anatomy and function. PeerJ 2015; 3:e1245. [PMID: 26401455 PMCID: PMC4579021 DOI: 10.7717/peerj.1245] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Accepted: 08/25/2015] [Indexed: 12/03/2022] Open
Abstract
The quadrate of reptiles and most other tetrapods plays an important morphofunctional role by allowing the articulation of the mandible with the cranium. In Theropoda, the morphology of the quadrate is particularly complex and varies importantly among different clades of non-avian theropods, therefore conferring a strong taxonomic potential. Inconsistencies in the notation and terminology used in discussions of the theropod quadrate anatomy have been noticed, including at least one instance when no less than eight different terms were given to the same structure. A standardized list of terms and notations for each quadrate anatomical entity is proposed here, with the goal of facilitating future descriptions of this important cranial bone. In addition, an overview of the literature on quadrate function and pneumaticity in non-avian theropods is presented, along with a discussion of the inferences that could be made from this research. Specifically, the quadrate of the large majority of non-avian theropods is akinetic but the diagonally oriented intercondylar sulcus of the mandibular articulation allowed both rami of the mandible to move laterally when opening the mouth in many of theropods. Pneumaticity of the quadrate is also present in most averostran clades and the pneumatic chamber—invaded by the quadrate diverticulum of the mandibular arch pneumatic system—was connected to one or several pneumatic foramina on the medial, lateral, posterior, anterior or ventral sides of the quadrate.
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Affiliation(s)
- Christophe Hendrickx
- Departamento de Ciências da Terra, Universidade Nova de Lisboa, GeoBioTec, Faculdade de Ciências e Tecnologia , Caparica , Portugal ; Museu da Lourinhã , Lourinhã , Portugal ; Current affiliation: Evolutionary Studies Institute, Center of Excellence in Palaeosciences, University of the Witwatersrand , South Africa
| | - Ricardo Araújo
- Museu da Lourinhã , Lourinhã , Portugal ; Huffington Department of Earth Sciences, Southern Methodist University , Dallas, TX , USA ; Instituto Superior Técnico, Universidade de Lisboa , Lisboa , Portugal ; Museum für Naturkunde , Berlin , Germany
| | - Octávio Mateus
- Departamento de Ciências da Terra, Universidade Nova de Lisboa, GeoBioTec, Faculdade de Ciências e Tecnologia , Caparica , Portugal ; Museu da Lourinhã , Lourinhã , Portugal
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Lü J, Brusatte SL. A large, short-armed, winged dromaeosaurid (Dinosauria: Theropoda) from the Early Cretaceous of China and its implications for feather evolution. Sci Rep 2015; 5:11775. [PMID: 26181289 PMCID: PMC4504142 DOI: 10.1038/srep11775] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 04/10/2015] [Indexed: 11/16/2022] Open
Abstract
The famous ‘feathered dinosaurs’ from the Early Cretaceous of Liaoning Province, northeastern China, include several dromaeosaurids, which are among the closest relatives of birds. Most of these are small-bodied taxa with long arms and broad wings comprised of vaned feathers, but a single specimen (the holotype of Tianyuraptor) belongs to a much larger individual with reduced forelimbs, which unfortunately lacks any preserved integument. We describe a new specimen of large-bodied, short-armed Liaoning dromaeosaurid, which we designate as a new genus and species, Zhenyuanlong suni. The integument is well preserved and provides the first evidence of feather morphologies and distribution in a short-armed (and probably non-volant) dromaeosaurid, indicating that these rare and aberrant taxa had large wings consisting of pennaceous feathers on the arms and long pennaceous feathers on the tail very similar to their smaller and longer-armed relatives, but potentially lacked vaned feathers on the legs. Zhenyuanlong adds yet more diversity to the Liaoning dromaeosaurid fauna, helps further reveal a distinct short-armed bauplan among dromaeosaurids, and illuminates previously-unrecognized homoplasy that complicates dromaeosaurid phylogeny and suggests that the Liaoning taxa may not have formed their own clade.
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Affiliation(s)
- Junchang Lü
- Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China; Key Lab of Stratigraphy and Paleontology, Ministry of Land and Resources of China, Beijing 100037, China
| | - Stephen L Brusatte
- School of GeoSciences, University of Edinburgh, Grant Institute, James Hutton Road, Edinburgh EH9 3FE, United Kingdom
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The oldest record of ornithuromorpha from the early cretaceous of China. Nat Commun 2015; 6:6987. [PMID: 25942493 PMCID: PMC5426517 DOI: 10.1038/ncomms7987] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 03/20/2015] [Indexed: 11/09/2022] Open
Abstract
Ornithuromorpha is the most inclusive clade containing extant birds but not the Mesozoic Enantiornithes. The early evolutionary history of this avian clade has been advanced with recent discoveries from Cretaceous deposits, indicating that Ornithuromorpha and Enantiornithes are the two major avian groups in Mesozoic. Here we report on a new ornithuromorph bird, Archaeornithura meemannae gen. et sp. nov., from the second oldest avian-bearing deposits (130.7 Ma) in the world. The new taxon is referable to the Hongshanornithidae and constitutes the oldest record of the Ornithuromorpha. However, A. meemannae shows few primitive features relative to younger hongshanornithids and is deeply nested within the Hongshanornithidae, suggesting that this clade is already well established. The new discovery extends the record of Ornithuromorpha by five to six million years, which in turn pushes back the divergence times of early avian lingeages into the Early Cretaceous.
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Pei R, Li Q, Meng Q, Gao KQ, Norell MA. A New Specimen ofMicroraptor(Theropoda: Dromaeosauridae) from the Lower Cretaceous of Western Liaoning, China. AMERICAN MUSEUM NOVITATES 2014. [DOI: 10.1206/3821.1] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Balanoff AM, Bever GS, Norell MA. Reconsidering the Avian Nature of the Oviraptorosaur Brain (Dinosauria: Theropoda). PLoS One 2014; 9:e113559. [PMID: 25494183 PMCID: PMC4262302 DOI: 10.1371/journal.pone.0113559] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Accepted: 10/25/2014] [Indexed: 11/19/2022] Open
Abstract
The high degree of encephalization characterizing modern birds is the product of a long evolutionary history, our understanding of which is still largely in its infancy. Here we provide a redescription of the endocranial space of the oviraptorosaurian dinosaur Conchoraptor gracilis with the goal of assessing the hypothesis that it shares uniquely derived endocranial characters with crown-group avians. The existence of such features has implications for the transformational history of avian neuroanatomy and suggests that the oviraptorosaur radiation is a product of the immediate stem lineage of birds-after the divergence of Archaeopteryx lithographica. Results derived from an expanded comparative sample indicate that the strong endocranial similarity between Conchoraptor and modern birds largely reflects shared conservation of plesiomorphic features. The few characters that are maintained as being uniquely expressed in these two taxa are more likely products of convergence than homology but still indicate that the oviraptorosaur endocranial cavity has much to teach us about the complex history of avian brain evolution.
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Affiliation(s)
- Amy M. Balanoff
- Stony Brook University, Department of Anatomical Sciences, Stony Brook, New York, United States of America
- American Museum of Natural History, Division of Paleontology, Central Park West at 79 Street, New York, New York, United States of America
- * E-mail:
| | - G. S. Bever
- New York Institute of Technology, College of Osteopathic Medicine, Department of Anatomy, Northern Boulevard, Old Westbury, New York, United States of America
- American Museum of Natural History, Division of Paleontology, Central Park West at 79 Street, New York, New York, United States of America
| | - Mark A. Norell
- American Museum of Natural History, Division of Paleontology, Central Park West at 79 Street, New York, New York, United States of America
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Choiniere JN, Clark JM, Norell MA, Xu X. Cranial Osteology ofHaplocheirus sollersChoiniere et al., 2010 (Theropoda: Alvarezsauroidea). AMERICAN MUSEUM NOVITATES 2014. [DOI: 10.1206/3816.1] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Hendrickx C, Mateus O. Torvosaurus gurneyi n. sp., the largest terrestrial predator from Europe, and a proposed terminology of the maxilla anatomy in nonavian theropods. PLoS One 2014; 9:e88905. [PMID: 24598585 PMCID: PMC3943790 DOI: 10.1371/journal.pone.0088905] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 01/07/2014] [Indexed: 11/18/2022] Open
Abstract
The Lourinhã Formation (Kimmeridgian-Tithonian) of Central West Portugal is well known for its diversified dinosaur fauna similar to that of the Morrison Formation of North America; both areas share dinosaur taxa including the top predator Torvosaurus, reported in Portugal. The material assigned to the Portuguese T. tanneri, consisting of a right maxilla and an incomplete caudal centrum, was briefly described in the literature and a thorough description of these bones is here given for the first time. A comparison with material referred to Torvosaurus tanneri allows us to highlight some important differences justifying the creation of a distinct Eastern species. Torvosaurus gurneyi n. sp. displays two autapomorphies among Megalosauroidea, a maxilla possessing fewer than eleven teeth and an interdental wall nearly coincidental with the lateral wall of the maxillary body. In addition, it differs from T. tanneri by a reduced number of maxillary teeth, the absence of interdental plates terminating ventrally by broad V-shaped points and falling short relative to the lateral maxillary wall, and the absence of a protuberant ridge on the anterior part of the medial shelf, posterior to the anteromedial process. T. gurneyi is the largest theropod from the Lourinhã Formation of Portugal and the largest land predator discovered in Europe hitherto. This taxon supports the mechanism of vicariance that occurred in the Iberian Meseta during the Late Jurassic when the proto-Atlantic was already well formed. A fragment of maxilla from the Lourinhã Formation referred to Torvosaurus sp. is ascribed to this new species, and several other bones, including a femur, a tibia and embryonic material all from the Kimmeridgian-Tithonian of Portugal, are tentatively assigned to T. gurneyi. A standard terminology and notation of the theropod maxilla is also proposed and a record of the Torvosaurus material from Portugal is given.
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Affiliation(s)
- Christophe Hendrickx
- Departamento de Ciências da Terra, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
- Museu da Lourinhã, Lourinhã, Portugal
- * E-mail:
| | - Octávio Mateus
- Departamento de Ciências da Terra, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
- Museu da Lourinhã, Lourinhã, Portugal
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42
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A new dromaeosaurid (Dinosauria: Theropoda) with Asian affinities from the latest Cretaceous of North America. Naturwissenschaften 2013; 100:1041-9. [DOI: 10.1007/s00114-013-1107-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 08/10/2013] [Accepted: 08/14/2013] [Indexed: 10/26/2022]
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43
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Bever GS, Brusatte SL, Carr TD, Xu X, Balanoff AM, Norell MA. The Braincase Anatomy of the Late Cretaceous DinosaurAlioramus(Theropoda: Tyrannosauroidea). BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY 2013. [DOI: 10.1206/810.1] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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44
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Brusatte SL, Vremir M, Csiki-Sava Z, Turner AH, Watanabe A, Erickson GM, Norell MA. The Osteology of Balaur bondoc, an Island-Dwelling Dromaeosaurid (Dinosauria: Theropoda) from the Late Cretaceous of Romania. BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY 2013. [DOI: 10.1206/798.1] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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45
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Multivariate analyses of small theropod dinosaur teeth and implications for paleoecological turnover through time. PLoS One 2013; 8:e54329. [PMID: 23372708 PMCID: PMC3553132 DOI: 10.1371/journal.pone.0054329] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 12/11/2012] [Indexed: 11/19/2022] Open
Abstract
Isolated small theropod teeth are abundant in vertebrate microfossil assemblages, and are frequently used in studies of species diversity in ancient ecosystems. However, determining the taxonomic affinities of these teeth is problematic due to an absence of associated diagnostic skeletal material. Species such as Dromaeosaurus albertensis, Richardoestesia gilmorei, and Saurornitholestes langstoni are known from skeletal remains that have been recovered exclusively from the Dinosaur Park Formation (Campanian). It is therefore likely that teeth from different formations widely disparate in age or geographic position are not referable to these species. Tooth taxa without any associated skeletal material, such as Paronychodon lacustris and Richardoestesia isosceles, have also been identified from multiple localities of disparate ages throughout the Late Cretaceous. To address this problem, a dataset of measurements of 1183 small theropod teeth (the most specimen-rich theropod tooth dataset ever constructed) from North America ranging in age from Santonian through Maastrichtian were analyzed using multivariate statistical methods: canonical variate analysis, pairwise discriminant function analysis, and multivariate analysis of variance. The results indicate that teeth referred to the same taxon from different formations are often quantitatively distinct. In contrast, isolated teeth found in time equivalent formations are not quantitatively distinguishable from each other. These results support the hypothesis that small theropod taxa, like other dinosaurs in the Late Cretaceous, tend to be exclusive to discrete host formations. The methods outlined have great potential for future studies of isolated teeth worldwide, and may be the most useful non-destructive technique known of extracting the most data possible from isolated and fragmentary specimens. The ability to accurately assess species diversity and turnover through time based on isolated teeth will help illuminate patterns of evolution and extinction in these groups and potentially others in greater detail than has previously been thought possible without more complete skeletal material.
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46
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Balanoff AM, Norell MA. Osteology of Khaan mckennai (Oviraptorosauria: Theropoda). BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY 2012. [DOI: 10.1206/803.1] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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47
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Turner AH, Makovicky PJ, Norell MA. A Review of Dromaeosaurid Systematics and Paravian Phylogeny. BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY 2012. [DOI: 10.1206/748.1] [Citation(s) in RCA: 207] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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48
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Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany. Proc Natl Acad Sci U S A 2012; 109:11746-51. [PMID: 22753486 DOI: 10.1073/pnas.1203238109] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recent discoveries in Asia have greatly increased our understanding of the evolution of dinosaurs' integumentary structures, revealing a previously unexpected diversity of "protofeathers" and feathers. However, all theropod dinosaurs with preserved feathers reported so far are coelurosaurs. Evidence for filaments or feathers in noncoelurosaurian theropods is circumstantial and debated. Here we report an exceptionally preserved skeleton of a juvenile megalosauroid, Sciurumimus albersdoerferi n. gen., n. sp., from the Late Jurassic of Germany, which preserves a filamentous plumage at the tail base and on parts of the body. These structures are identical to the type 1 feathers that have been reported in some ornithischians, the basal tyrannosaur Dilong, the basal therizinosauroid Beipiaosaurus, and, probably, in the basal coelurosaur Sinosauropteryx. Sciurumimus albersdoerferi represents the phylogenetically most basal theropod that preserves direct evidence for feathers and helps close the gap between feathers reported in coelurosaurian theropods and filaments in ornithischian dinosaurs, further supporting the homology of these structures. The specimen of Sciurumimus is the most complete megalosauroid yet discovered and helps clarify significant anatomical details of this important basal theropod clade, such as the complete absence of the fourth digit of the manus. The dentition of this probably early-posthatchling individual is markedly similar to that of basal coelurosaurian theropods, indicating that coelurosaur occurrences based on isolated teeth should be used with caution.
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Brocklehurst N, Upchurch P, Mannion PD, O'Connor J. The completeness of the fossil record of mesozoic birds: implications for early avian evolution. PLoS One 2012; 7:e39056. [PMID: 22761723 PMCID: PMC3382576 DOI: 10.1371/journal.pone.0039056] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Accepted: 05/15/2012] [Indexed: 11/18/2022] Open
Abstract
Many palaeobiological analyses have concluded that modern birds (Neornithes) radiated no earlier than the Maastrichtian, whereas molecular clock studies have argued for a much earlier origination. Here, we assess the quality of the fossil record of Mesozoic avian species, using a recently proposed character completeness metric which calculates the percentage of phylogenetic characters that can be scored for each taxon. Estimates of fossil record quality are plotted against geological time and compared to estimates of species level diversity, sea level, and depositional environment. Geographical controls on the avian fossil record are investigated by comparing the completeness scores of species in different continental regions and latitudinal bins. Avian fossil record quality varies greatly with peaks during the Tithonian-early Berriasian, Aptian, and Coniacian–Santonian, and troughs during the Albian-Turonian and the Maastrichtian. The completeness metric correlates more strongly with a ‘sampling corrected’ residual diversity curve of avian species than with the raw taxic diversity curve, suggesting that the abundance and diversity of birds might influence the probability of high quality specimens being preserved. There is no correlation between avian completeness and sea level, the number of fluviolacustrine localities or a recently constructed character completeness metric of sauropodomorph dinosaurs. Comparisons between the completeness of Mesozoic birds and sauropodomorphs suggest that small delicate vertebrate skeletons are more easily destroyed by taphonomic processes, but more easily preserved whole. Lagerstätten deposits might therefore have a stronger impact on reconstructions of diversity of smaller organisms relative to more robust forms. The relatively poor quality of the avian fossil record in the Late Cretaceous combined with very patchy regional sampling means that it is possible neornithine lineages were present throughout this interval but have not yet been sampled or are difficult to identify because of the fragmentary nature of the specimens.
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Affiliation(s)
- Neil Brocklehurst
- Museum für Naturkunde, Leibniz-Institut für Evolutions und Biodiversitätsforschung, Berlin, Germany.
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50
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Senter P, Kirkland JI, DeBlieux DD, Madsen S, Toth N. New Dromaeosaurids (Dinosauria: Theropoda) from the lower cretaceous of Utah, and the evolution of the Dromaeosaurid tail. PLoS One 2012; 7:e36790. [PMID: 22615813 PMCID: PMC3352940 DOI: 10.1371/journal.pone.0036790] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 04/11/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The Yellow Cat Member of the Cedar Mountain Formation (Early Cretaceous, Barremian?--Aptian) of Utah has yielded a rich theropod fauna, including the coelurosaur Nedcolbertia justinhofmanni, the therizinosauroid Falcarius utahensis, the troodontid Geminiraptor suarezarum, and the dromaeosaurid Utahraptor ostrommaysorum. Recent excavation has uncovered three new dromaeosaurid specimens. One specimen, which we designate the holotype of the new genus and species Yurgovuchia doellingi, is represented by a partial axial skeleton and a partial left pubis. A second specimen consists of a right pubis and a possibly associated radius. The third specimen consists of a tail skeleton that is unique among known Cedar Mountain dromaeosaurids. METHODOLOGY/PRINCIPAL FINDINGS Y. doellingi resembles Utahraptor ostrommaysorum in that its caudal prezygapophyses are elongated but not to the degree present in most dromaeosaurids. The specimen represented by the right pubis exhibits a pronounced pubic tubercle, a velociraptorine trait that is absent in Y. doellingi. The specimen represented by the tail skeleton exhibits the extreme elongation of the caudal prezygapophyses that is typical of most dromaeosaurids. Here we perform a phylogenetic analysis to determine the phylogenetic position of Y. doellingi. Using the resulting phylogeny as a framework, we trace changes in character states of the tail across Coelurosauria to elucidate the evolution of the dromaeosaurid tail. CONCLUSIONS/SIGNIFICANCE The new specimens add to the known diversity of Dromaeosauridae and to the known diversity within the Yellow Cat paleofauna. Phylogenetic analysis places Y. doellingi in a clade with Utahraptor, Achillobator, and Dromaeosaurus. Character state distribution indicates that the presence of intermediate-length caudal prezygapophyses in that clade is not an evolutionarily precursor to extreme prezygapophyseal elongation but represents a secondary shortening of caudal prezygapophyses. It appears to represent part of a trend within Dromaeosauridae that couples an increase in tail flexibility with increasing size.
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Affiliation(s)
- Phil Senter
- Department of Biological Sciences, Fayetteville State University, Fayetteville, North Carolina, United States of America.
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