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Meso JG, Gianechini F, Gomez KL, Muci L, Baiano MA, Pol D, Kaluza J, Garrido A, Pittman M. Shed teeth from Portezuelo formation at Sierra del Portezuelo reveal a higher diversity of predator theropods during Turonian-Coniacian times in northern Patagonia. BMC Ecol Evol 2024; 24:59. [PMID: 38730384 PMCID: PMC11083846 DOI: 10.1186/s12862-024-02249-8] [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: 02/27/2024] [Accepted: 04/30/2024] [Indexed: 05/12/2024] Open
Abstract
The study of thirty-two shed crowns from the Portezuelo Formation (middle Turonian-late Coniacian) at the Sierra del Portezuelo locality, reveals six distinct tooth morphotypes identified through cladistic, discriminant, and cluster analyses. Two morphotypes were identified as belonging to Megaraptoridae, three to Abelisauridae, one to Abelisauroidea, and one to Alvarezsauridae. Additionally, two of the morphotypes exhibit a combination of dental features typically found in megaraptorid and abelisauridtheropods. These results suggest a greater diversity of theropods in the original ecosystem than previously thought, including the presence of a second morphotype of megaraptorid and alvarezsaurid previously undocumented in this formation. Furthermore, the existence of Morphotype 6 indicates the potential coexistence of medium-sized abelisauroids alongside larger abelisaurids in the same ecosystem. These findings underscore the importance of future expeditions to the Sierra del Portezuelo locality to further our understanding of these previously unknown theropod species.
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Affiliation(s)
- Jorge Gustavo Meso
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
- Instituto de Investigación en Paleobiología y Geología (IIPG), Universidad Nacional de Río Negro (UNRN) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), General Roca, Río Negro, 8332, Argentina.
- Universidad Nacional de Río Negro, Sede Alto Valle/Valle Medio, R8332 General Roca, Estados Unidos 750, Río Negro, Argentina.
| | - Federico Gianechini
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Instituto Multidisciplinario de Investigaciones Biológicas de San Luis (IMIBIO-SL), Universidad Nacional de San Luis, San Luis, Argentina
| | - Kevin Leonel Gomez
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Instituto de Investigación en Paleobiología y Geología (IIPG), Universidad Nacional de Río Negro (UNRN) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), General Roca, Río Negro, 8332, Argentina
| | - Luciana Muci
- Universidad Nacional de Río Negro, Sede Alto Valle/Valle Medio, R8332 General Roca, Estados Unidos 750, Río Negro, Argentina
| | - Mattia Antonio Baiano
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Universidad Nacional de Río Negro, Sede Alto Valle/Valle Medio, R8332 General Roca, Estados Unidos 750, Río Negro, Argentina
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- DrNatali S/N, Área Laboratorio E Investigación, Museo Municipal 'Ernesto Bachmann', 8311 Villa El Chocon, Neuquén, Argentina
| | - Diego Pol
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Museo Paleontológico Egidio Feruglio, Trelew, Chubut, Argentina
| | - Jonatan Kaluza
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Fundación de Historia Natural Félix de Azara, Universidad Maimónides. Hidalgo 775, Ciudad Autónoma de Buenos Aires, C1405, Argentina
| | - Alberto Garrido
- Museo Provincial de Ciencias Naturales 'Prof. Dr. Juan A. Olsacher'. Dirección Provincial de Minería, Zapala, Neuquén, Argentina
| | - Michael Pittman
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
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2
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Senter PJ. Restudy of shoulder motion in the theropod dinosaur Mononykus olecranus (Alvarezsauridae). PeerJ 2023; 11:e16605. [PMID: 38077415 PMCID: PMC10704983 DOI: 10.7717/peerj.16605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 11/15/2023] [Indexed: 12/18/2023] Open
Abstract
Background Range of motion in the forelimb of the Upper Cretaceous theropod dinosaur Mononykus olecranus, a member of the family Alvarezsauridae, has previously been investigated. However, the method used to investigate range of motion at the shoulder in M. olecranus did not follow the standardized procedure used in subsequent studies. The latter procedure yields more reliable results, and its standardization provides that its results are directly comparable to the results of similar studies in other species. I therefore reinvestigated the range of motion at the shoulder in M. olecranus, using the latter procedure. Methods Casts of the left scapula and coracoid of M. olecranus were posed on a horizontal surface, supported from beneath with modeling clay, with the medial surface of the scapula facing toward the horizontal surface. A cast of the left humerus was posed at the limits of motion through the transverse and parasagittal planes. Photos of the poses in orthal views were superimposed and used to measure range of motion, which was measured as the angle between lines drawn down the long axis of the humerus in each position. Results Through the transverse plane, the humerus of M. olecranus could be elevated to a subhorizontal position and depressed to a subvertical position. It could move through the parasagittal plane from a subvertical position at full protraction to a position above the horizontal at full retraction. These results correct the previous mischaracterization of shoulder motion in M. olecranus as restricted to a small arc with the arms held in a permanent sprawl. The range of humeral motion in M. olecranus is much greater than that found by the previous method and allowed the animal to tuck its arms in at the sides, in addition to allowing them to sprawl so as to orient the palm downward. The wide range of humeral motion allowed M. olecranus to forage for insects by employing hook-and-pull digging at surfaces with a wider range of orientations than the previous study showed to be possible.
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Affiliation(s)
- Philip J. Senter
- Department of Biological and Forensic Sciences, Fayetteville State University, Fayetteville, North Carolina, United States
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3
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Kubo K, Kobayashi Y, Chinzorig T, Tsogtbaatar K. A new alvarezsaurid dinosaur (Theropoda, Alvarezsauria) from the Upper Cretaceous Baruungoyot Formation of Mongolia provides insights for bird-like sleeping behavior in non-avian dinosaurs. PLoS One 2023; 18:e0293801. [PMID: 37967055 PMCID: PMC10651048 DOI: 10.1371/journal.pone.0293801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 10/19/2023] [Indexed: 11/17/2023] Open
Abstract
Alvarezsauria is a group of early-branching maniraptoran theropods that are distributed globally from the Late Jurassic to the latest Cretaceous. Despite recent increases in the fossil record of this group, the scarcity of complete specimens still restricts interpreting their detailed anatomy, ecology, and evolution. Here, we report a new taxon of derived alvarezsaur, Jaculinykus yaruui gen. et sp. nov., from the Late Cretaceous of Mongolia, which represents a nearly complete and articulated skeleton. Our phylogenetic analysis reveals that Jaculinykus belongs to the sub-clade of Alvarezsauridae, Parvicursorinae, and forms a mononphyletic group with Mononykus and Shuvuuia. Its well-preserved manus has only two fingers, composed of a hypertrophied digit I and greatly reduced digit II, which implies an intermediate condition between the tridactyl manus of Shuvuuia and monodactyl manus of Linhenykus. This highlights a previously unrecognized variation in specialization of alvarezsaurid manus. Notably, the preserved posture of the specimen exhibits a stereotypical avian-like sleeping position seen in the troodontids Mei and Sinornithoides. Evidence of this behavior in the alvarezsaur Jaculinykus suggests that stereotypically avian sleeping postures are a maniraptoran synapomorphy, providing more evidence of bird-like traits being distributed broadly among avian ancestors.
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Affiliation(s)
- Kohta Kubo
- Department of Natural History and Planetary Sciences, Hokkaido University, Kita-ku, Sapporo, Hokkaido, Japan
| | | | - Tsogtbaatar Chinzorig
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, United States of America
- Institute of Paleontology, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia
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4
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Xu L, Wang M, Chen R, Dong L, Lin M, Xu X, Tang J, You H, Zhou G, Wang L, He W, Li Y, Zhang C, Zhou Z. A new avialan theropod from an emerging Jurassic terrestrial fauna. Nature 2023; 621:336-343. [PMID: 37674081 DOI: 10.1038/s41586-023-06513-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 08/02/2023] [Indexed: 09/08/2023]
Abstract
Birds are descended from non-avialan theropod dinosaurs of the Late Jurassic period, but the earliest phase of this evolutionary process remains unclear owing to the exceedingly sparse and spatio-temporally restricted fossil record1-5. Information about the early-diverging species along the avialan line is crucial to understand the evolution of the characteristic bird bauplan, and to reconcile phylogenetic controversies over the origin of birds3,4. Here we describe one of the stratigraphically youngest and geographically southernmost Jurassic avialans, Fujianvenator prodigiosus gen. et sp. nov., from the Tithonian age of China. This specimen exhibits an unusual set of morphological features that are shared with other stem avialans, troodontids and dromaeosaurids, showing the effects of evolutionary mosaicism in deep avialan phylogeny. F. prodigiosus is distinct from all other Mesozoic avialan and non-avialan theropods in having a particularly elongated hindlimb, suggestive of a terrestrial or wading lifestyle-in contrast with other early avialans, which exhibit morphological adaptations to arboreal or aerial environments. During our fieldwork in Zhenghe where F. prodigiosus was found, we discovered a diverse assemblage of vertebrates dominated by aquatic and semi-aquatic species, including teleosts, testudines and choristoderes. Using in situ radioisotopic dating and stratigraphic surveys, we were able to date the fossil-containing horizons in this locality-which we name the Zhenghe Fauna-to 148-150 million years ago. The diversity of the Zhenghe Fauna and its precise chronological framework will provide key insights into terrestrial ecosystems of the Late Jurassic.
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Affiliation(s)
- Liming Xu
- Fujian Institute of Geological Survey, Fuzhou, China
| | - Min Wang
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.
| | - Runsheng Chen
- Fujian Institute of Geological Survey, Fuzhou, China
| | - Liping Dong
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| | - Min Lin
- Fujian Institute of Geological Survey, Fuzhou, China
| | - Xing Xu
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- Centre for Vertebrate Evolutionary Biology, Yunnan University, Kunming, China
- Paleontological Museum of Liaoning, Shenyang Normal University, Shenyang, China
| | - Jianrong Tang
- Fujian Institute of Geological Survey, Fuzhou, China
| | - Hailu You
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| | - Guowu Zhou
- Fujian Institute of Geological Survey, Fuzhou, China
| | - Linchang Wang
- Fujian Institute of Geological Survey, Fuzhou, China
| | - Wenxing He
- Fujian Institute of Geological Survey, Fuzhou, China
| | - Yujuan Li
- Fujian Institute of Geological Survey, Fuzhou, China
| | - Chi Zhang
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, 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
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5
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Wang M, Zhou Z. Low morphological disparity and decelerated rate of limb size evolution close to the origin of birds. Nat Ecol Evol 2023; 7:1257-1266. [PMID: 37277496 DOI: 10.1038/s41559-023-02091-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 05/09/2023] [Indexed: 06/07/2023]
Abstract
The origin of birds from theropod dinosaurs involves many changes in musculoskeletal anatomy and epidermal structures, including multiple instances of convergence and homology-related traits that contribute to the refinement of flight capability. Changes in limb sizes and proportions are important for locomotion (for example, the forelimb for bird flight); thus, understanding these patterns is central to investigating the transition from terrestrial to volant theropods. Here we analyse the patterns of morphological disparity and the evolutionary rate of appendicular limbs along avialan stem lineages using phylogenetic comparative approaches. Contrary to the traditional wisdom that an evolutionary innovation like flight would promote and accelerate evolvability, our results show a shift to low disparity and decelerated rate near the origin of avialans that is largely ascribed to the evolutionarily constrained forelimb. These results suggest that natural selection shaped patterns of limb evolution close to the origin of avialans in a way that may reflect the winged forelimb 'blueprint' associated with powered flight.
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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.
| | - Zhonghe Zhou
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
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6
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D'Emic MD, O'Connor PM, Sombathy RS, Cerda I, Pascucci TR, Varricchio D, Pol D, Dave A, Coria RA, Curry Rogers KA. Developmental strategies underlying gigantism and miniaturization in non-avialan theropod dinosaurs. Science 2023; 379:811-814. [PMID: 36821658 DOI: 10.1126/science.adc8714] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
In amniotes, the predominant developmental strategy underlying body size evolution is thought to be adjustments to the rate of growth rather than its duration. However, most theoretical and experimental studies supporting this axiom focus on pairwise comparisons and/or lack an explicit phylogenetic framework. We present the first large-scale phylogenetic comparative analysis examining developmental strategies underlying the evolution of body size, focusing on non-avialan theropod dinosaurs. We reconstruct ancestral states of growth rate and body mass in a taxonomically rich dataset, finding that contrary to expectations, changes in the rate and duration of growth played nearly equal roles in the evolution of the vast body size disparity present in non-avialan theropods-and perhaps that of amniotes in general.
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Affiliation(s)
- Michael D D'Emic
- Department of Biology, Adelphi University, Garden City, NY, USA
- Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY, USA
| | - Patrick M O'Connor
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine, Athens, OH, USA
- Ohio Center for Ecological and Evolutionary Studies, Ohio University, Athens, OH, USA
| | - Riley S Sombathy
- Department of Biology, Adelphi University, Garden City, NY, USA
- Ohio Center for Ecological and Evolutionary Studies, Ohio University, Athens, OH, USA
- Department of Biological Sciences, Ohio University, Athens, OH, USA
| | - Ignacio Cerda
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, República Argentina
- Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro, Museo Carlos Ameghino, Cipolletti, Río Negro, Argentina
| | | | - David Varricchio
- Department of Earth Sciences, Montana State University, Bozeman, MT, USA
| | - Diego Pol
- CONICET-Museo Paleontológico Egidio Feruglio, Trelew, Chubut, Argentina
| | - Anjali Dave
- Department of Biology, Adelphi University, Garden City, NY, USA
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7
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Qin Z, Liao CC, Benton MJ, Rayfield EJ. Functional space analyses reveal the function and evolution of the most bizarre theropod manual unguals. Commun Biol 2023; 6:181. [PMID: 36797463 PMCID: PMC9935540 DOI: 10.1038/s42003-023-04552-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 02/03/2023] [Indexed: 02/18/2023] Open
Abstract
Maniraptoran dinosaurs include the ancestors of birds, and most used their hands for grasping and in flight, but early-branching maniraptorans had extraordinary claws of mysterious function. Alvarezsauroids had short, strong arms and hands with a stout, rock-pick-like, single functional finger. Therizinosaurians had elongate fingers with slender and sickle-like unguals, sometimes over one metre long. Here we develop a comprehensive methodological framework to investigate what the functions of these most bizarre bony claws are and how they formed. Our analysis includes finite element analysis and a newly established functional-space analysis and also involves shape and size effects in an assessment of function and evolution. We find a distinct functional divergence among manual unguals of early-branching maniraptorans, and we identify a complex relationship between their structural strength, morphological specialisations, and size changes. Our analysis reveals that efficient digging capabilities only emerged in late-branching alvarezsauroid forelimbs, rejecting the hypothesis of functional vestigial structures like T. rex. Our results also support the statement that most therizinosaurians were herbivores. However, the bizarre, huge Therizinosaurus had sickle-like unguals of such length that no mechanical function has been identified; we suggest they were decorative and lengthened by peramorphic growth linked to increased body size.
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Affiliation(s)
- Zichuan Qin
- School of Earth Sciences, Life Sciences Building, University of Bristol, Tyndall Avenue, Bristol, BS8 1TQ, UK.
| | - Chun-Chi Liao
- grid.9227.e0000000119573309Key Laboratory for the Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, 100044 China
| | - Michael J. Benton
- grid.5337.20000 0004 1936 7603School of Earth Sciences, Life Sciences Building, University of Bristol, Tyndall Avenue, Bristol, BS8 1TQ UK
| | - Emily J. Rayfield
- grid.5337.20000 0004 1936 7603School of Earth Sciences, Life Sciences Building, University of Bristol, Tyndall Avenue, Bristol, BS8 1TQ UK
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8
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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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9
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Guinard G. THE FORELIMBS OF ALVAREZSAUROIDEA (DINOSAURIA: THEROPODA): INSIGHT FROM EVOLUTIONARY TERATOLOGY. J Morphol 2022; 283:1257-1272. [PMID: 35915891 DOI: 10.1002/jmor.21500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 07/14/2022] [Accepted: 07/17/2022] [Indexed: 11/09/2022]
Abstract
Alvarezsauroidea (Tetanurae) are non-avian theropod dinosaurs whose forelimb evolution is characterised by overdevelopment of digit I, at the expense of the other two digits, complemented by a drastic forelimb shortening in derived species (Parvicursorinae). These variations are recognised as evolutionary developmental anomalies. Evolutionary teratology hence leads to a double diagnosis with 1) macrodactyly of digit I and microdactyly of digits II and III, plus 2) anterior micromelia. The teratological macrodactyly/microdactyly coupling evolved first. Developmental mechanisms disturbing limb proportion are thought to be convergent with those of other Tetanurae (Tyrannosauridae, Carcharodontosauridae). As for the manual anomalies, both are specific to Alvarezsauroidea (macrodactyly/microdactyly) and inherited (digit loss/reduction). While considering the frame-shift theory, posterior digits develop before the most anterior one. There would therefore be a decrease in the area devoted to digits II (condensation 3) and III (condensation 4), in connection with the Shh signalling pathway, interacting with other molecular players such as the GLI 3 protein and the Hox system. Developmental independence of digit I (condensation 2) would contribute to generate a particular morphology. Macrodactyly would be linked to a variation in Hoxd-13, impacting Gli3 activity, increasing cell proliferation. The loss/reduction of digital ray/phalanges (digits II and III), would be associated to Shh activity, a mechanism inherited from the theropodan ancestry. The macrodactyly/macrodactyly coupling, and then anterior micromelia, fundamentally changed the forelimb mechanical function, compared to the 'classical' grasping structure of basal representatives and other theropods. The distal ossification of the macrodactylian digit has been identified as physiological, implying the use of the structure. However, the debate of a particular 'adaptive' use is pointless since the ecology of an organism is interactively complex, being both at the scale of the individual and dependent on circumstances. Other anatomical features also allow for compensation and a different predation (cursorial hindlimbs). This article is protected by copyright. All rights reserved.
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10
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Wang X, Bandeira KLN, Qiu R, Jiang S, Cheng X, Ma Y, Kellner AWA. The first dinosaurs from the Early Cretaceous Hami Pterosaur Fauna, China. Sci Rep 2021; 11:14962. [PMID: 34385481 PMCID: PMC8361124 DOI: 10.1038/s41598-021-94273-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 07/08/2021] [Indexed: 11/18/2022] Open
Abstract
The Early Cretaceous Hami Pterosaur Fauna in Northwest China preserves a large number of specimens of the sexually dimorphic pteranodontoid pterosaur Hamipterus tianshanensis, including 3D eggs and embryos. During the last decade, several more fossils have been collected in this area, including three somphospondylan sauropod specimens. The first is Silutitan sinensis gen. et sp. nov., which consists of an articulated middle to posterior cervical vertebrae series. The second, Hamititan xinjiangensis gen. et sp. nov., consists of an incomplete articulated caudal sequence that could be assigned to lithostrotian titanosaurs based on the strongly procoelous caudal vertebrae with lateral concave surface, as well as marked ventrolateral ridges. The third specimen consists of four sacral vertebral elements, apparently unfused, with exposed camellate internal bone and regarded as somphospondylan. Cladistic analyses based on different datasets recovered Silutitan sinensis as an euhelopodid closely related to Euhelopus and Hamititan xinjiangensis as a titanosaur. Besides the pterosaur Hamipterus and one theropod tooth, these dinosaurs are the first vertebrates reported in this region, increasing the diversity of the fauna as well as the information on Chinese sauropods, further supporting a widespread diversification of somphospondylans during the Early Cretaceous of Asia.
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Affiliation(s)
- Xiaolin Wang
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, 100044, China.
- CAS Center for Excellence in Life and Paleoenvironment, Beijing, 100044, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Kamila L N Bandeira
- Laboratory of Systematics and Taphonomy of Fossil Vertebrates, Department of Geology and Paleontology, Museu Nacional/Universidade Federal do Rio de Janeiro , Rio de Janeiro, 20940-040, Brazil
| | - Rui Qiu
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, 100044, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
- Beijing Museum of Natural History, Beijing, 100050, China
| | - Shunxing Jiang
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, 100044, China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing, 100044, China
| | - Xin Cheng
- Laboratório de Paleontologia da URCA, Universidade Regional do Cariri, Rua Carolino Sucupira, s/n, Crato, 63100-000, Brazil
- College of Earth Sciences, Jilin University, Changchun, 130061, China
| | | | - Alexander W A Kellner
- Laboratory of Systematics and Taphonomy of Fossil Vertebrates, Department of Geology and Paleontology, Museu Nacional/Universidade Federal do Rio de Janeiro , Rio de Janeiro, 20940-040, Brazil.
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11
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Qin Z, Zhao Q, Choiniere JN, Clark JM, Benton MJ, Xu X. Growth and miniaturization among alvarezsauroid dinosaurs. Curr Biol 2021; 31:3687-3693.e5. [PMID: 34233160 DOI: 10.1016/j.cub.2021.06.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 04/06/2021] [Accepted: 06/07/2021] [Indexed: 11/28/2022]
Abstract
Sustained miniaturization, here defined as a drop in body size of at least two orders of magnitude from ancestors to descendants, is a widespread and important phenomenon in animals,1-3 but among dinosaurs, miniaturization occurred only rarely, once in the lineage leading to birds and once in the Alvarezsauroidea,1,3-5 one of the most bizarre theropod groups.1,5-7 Miniaturization and powered flight are intimately linked in avialan theropods,3,5,6,8-11 but the causes and patterns of body size reduction are less clear in the non-volant Alvarezsauroidea.1,5,6,12,13 Here, we present results from analyses on a comprehensive dataset, which not only includes new data from early-branching alvarezsauroids but also considers the ontogenetic effect based on histological data. Our analyses show that alvarezsauroid body mass underwent rapid miniaturization from around 110 to 85 mya and that there was a phylogenetic radiation of small-sized alvarezsauroids in the Late Cretaceous. Our analyses also indicate that growth strategies were highly variable among alvarezsauroids, with significant differences among extremely small taxa. The suggested alvarezsauroid miniaturization and associated phylogenetic radiation are coincident with the emergence of ants and termites, and combining previous functional morphological data, our study suggests that alvarezsauroid miniaturization might have been driven by ecological changes during the Cretaceous Terrestrial Revolution, more specifically by a shift to the myrmecophagous ecological niche.
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Affiliation(s)
- Zichuan Qin
- School of Earth Sciences, Life Sciences Building, University of Bristol, Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Qi Zhao
- Key Laboratory for the Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China; CAS Center of Excellence in Life and Paleoenvironment, Beijing 100044, China
| | - Jonah N Choiniere
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - James M Clark
- Department of Biological Sciences, George Washington University, Washington, DC, USA
| | - Michael J Benton
- School of Earth Sciences, Life Sciences Building, University of Bristol, Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Xing Xu
- Key Laboratory for the Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China; CAS Center of Excellence in Life and Paleoenvironment, Beijing 100044, China.
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12
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Li Y, Wang X, Jiang S. A new pterosaur tracksite from the Lower Cretaceous of Wuerho, Junggar Basin, China: inferring the first putative pterosaur trackmaker. PeerJ 2021; 9:e11361. [PMID: 34131515 PMCID: PMC8176908 DOI: 10.7717/peerj.11361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 04/06/2021] [Indexed: 11/30/2022] Open
Abstract
We report the discovery of 114 small pterosaur footprints preserved in a greyish-green fine sandstone slab comprising 57 manus imprints and 57 pes imprints. Due to the chaotic distribution of footprints, the trackways are difficult to recognize. The pes imprints are sub-triangular and enlongate, the metatarsal part is roughly subequal to the digital part. The manus imprints are asymmetrical, longer than wide, and the lengths of digits I–III gradually increase. According to the diagnostic features of the Wuerho small pterosaur tracks, the present set was classified as Pteraichnus and is different from the nine reported valid ichnospecies of Pteraichnus. We therefore propose a new ichnospecies, Pteraichnus wuerhoensis isp. nov. The description is based on the anatomical characteristics (lengths of digits I–IV, length of digital part, length of metatarsal part) extracted from the pes imprints and comparisons with the pes bone fossils of Noripterus complicidens. We infer that the footprints were probably left by N. complicidens and the total width of the wings was presumably 2–2.3 m. In addition, the high density (365 per square meter) and varied sizes of the Wuerho small pterosaur tracks suggest that many pterosaurs of different ages lived in Huangyangquan Reservoir tracksite 1 area. Thus the trackmakers may have had gregarious behavior.
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Affiliation(s)
- Yang 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.,College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Xiaolin 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.,College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Shunxing Jiang
- 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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13
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Choiniere JN, Neenan JM, Schmitz L, Ford DP, Chapelle KEJ, Balanoff AM, Sipla JS, Georgi JA, Walsh SA, Norell MA, Xu X, Clark JM, Benson RBJ. Evolution of vision and hearing modalities in theropod dinosaurs. Science 2021; 372:610-613. [PMID: 33958472 DOI: 10.1126/science.abe7941] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 03/12/2021] [Indexed: 11/02/2022]
Abstract
Owls and nightbirds are nocturnal hunters of active prey that combine visual and hearing adaptations to overcome limits on sensory performance in low light. Such sensory innovations are unknown in nonavialan theropod dinosaurs and are poorly characterized on the line that leads to birds. We investigate morphofunctional proxies of vision and hearing in living and extinct theropods and demonstrate deep evolutionary divergences of sensory modalities. Nocturnal predation evolved early in the nonavialan lineage Alvarezsauroidea, signaled by extreme low-light vision and increases in hearing sensitivity. The Late Cretaceous alvarezsauroid Shuvuuia deserti had even further specialized hearing acuity, rivaling that of today's barn owl. This combination of sensory adaptations evolved independently in dinosaurs long before the modern bird radiation and provides a notable example of convergence between dinosaurs and mammals.
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Affiliation(s)
- Jonah N Choiniere
- Evolutionary Studies Institute, University of the Witwatersrand, 1 Jan Smuts Avenue, Johannesburg 2000, South Africa
| | - James M Neenan
- Evolutionary Studies Institute, University of the Witwatersrand, 1 Jan Smuts Avenue, Johannesburg 2000, South Africa.,Oxford University Museum of Natural History, University of Oxford, Parks Road, Oxford OX1 3PW, UK
| | - Lars Schmitz
- W.M. Keck Science Department, Claremont McKenna, Scripps, and Pitzer Colleges, 925 N Mills Ave., Claremont, CA 91711, USA.,Dinosaur Institute, Los Angeles County Museum of Natural History, 900 Exposition Boulevard, Los Angeles, CA 90007, USA
| | - David P Ford
- Evolutionary Studies Institute, University of the Witwatersrand, 1 Jan Smuts Avenue, Johannesburg 2000, South Africa
| | - Kimberley E J Chapelle
- Evolutionary Studies Institute, University of the Witwatersrand, 1 Jan Smuts Avenue, Johannesburg 2000, South Africa.,Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA
| | - Amy M Balanoff
- Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA.,Department of Psychological and Brain Sciences, Johns Hopkins University, 3400 North Charles St., Baltimore, MD 21218, USA
| | - Justin S Sipla
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, 51 Newton Road, 100 Bowen Science Building, Iowa City, IA 52242, USA
| | - Justin A Georgi
- Department of Anatomy, College of Graduate Studies, Midwestern University, 19555 N 59th Avenue, Glendale, AZ 85308, USA
| | - Stig A Walsh
- Department of Natural Sciences, National Museums Scotland, Chambers Street, Edinburgh EH1 1JF, UK.,School of Geosciences, University of Edinburgh, Grant Institute, Hutton Road, Edinburgh EH9 3FE, UK
| | - Mark A Norell
- Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA
| | - Xing Xu
- Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 142 Xizhimenwai Street, Beijing 100044, China.,Chinese Academy of Sciences Center for Excellence in Life and Paleoenvironment, Beijing 100044, China
| | - James M Clark
- Department of Biological Sciences, The George Washington University, 2029 G St. NW, Washington, DC 20052, USA
| | - Roger B J Benson
- Evolutionary Studies Institute, University of the Witwatersrand, 1 Jan Smuts Avenue, Johannesburg 2000, South Africa. .,Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
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14
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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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15
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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 PMCID: PMC7163733 DOI: 10.1111/joa.13153] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [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 LuisCiudad de San LuisArgentina
| | - Marcos D. Ercoli
- Instituto de Ecorregiones Andinas (INECOA)Universidad Nacional de Jujuy‐CONICETIdGyMSan Salvador de JujuyArgentina
| | - Ignacio Díaz‐Martínez
- Instituto de Investigación en Paleobiologia y Geología (IIPG)CONICET‐Universidad Nacional de Río NegroGeneral RocaArgentina
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16
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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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17
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Lee S, Park JY, Lee YN, Kim SH, Lü J, Barsbold R, Tsogtbaatar K. A new alvarezsaurid dinosaur from the Nemegt Formation of Mongolia. Sci Rep 2019; 9:15493. [PMID: 31664171 PMCID: PMC6820876 DOI: 10.1038/s41598-019-52021-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 10/07/2019] [Indexed: 11/16/2022] Open
Abstract
Alvarezsaurid diversity has been markedly increased by recent discoveries from China. However, the number of alvarezsaurid specimens in the Nemegt Formation of Mongolia remained low since the initial report on Mononykus olecranus in 1993. Here we report three new alvarezsaurid specimens from this formation, which were associated with each other and also with multiple oviraptorid skeletons in a small multi-species assemblage. Two of the alvarezsaurid specimens represent a new taxon, Nemegtonykus citus gen. et sp. nov., which is mainly distinguished from other alvarezsaurids by the first sacral vertebra with a subtrapezoidal lamina, the second sacral centrum which is directly co-ossified with ilium, the posterodorsally oriented postacetabular process of ilium, and partial co-ossification between metatarsals II and IV. The other specimen is very similar to M. olecranus in morphology and referred to cf. Mononykus sp. Our phylogenetic analysis recovered Nemegtonykus as a parvicursorine forming a polytomy with several other taxa from the Gobi Desert. The presence of three alvarezsaurid individuals in the same locality indicates that the abundance of alvarezsaurids have been greatly underestimated in the Nemegt dinosaur faunas.
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Affiliation(s)
- Sungjin Lee
- School of Earth and Environmental Sciences, Seoul National University, Seoul, 08826, Republic of Korea
| | - Jin-Young Park
- School of Earth and Environmental Sciences, Seoul National University, Seoul, 08826, Republic of Korea
| | - Yuong-Nam Lee
- School of Earth and Environmental Sciences, Seoul National University, Seoul, 08826, Republic of Korea.
| | - Su-Hwan Kim
- School of Earth and Environmental Sciences, Seoul National University, Seoul, 08826, Republic of Korea
| | - Junchang Lü
- Institute of Geology, Chinese Academy of Geological Sciences, Beijing, 100037, China
| | - Rinchen Barsbold
- Institute of Paleontology and Geology, Mongolian Academy of Sciences, Ulaanbaatar, 15160, Mongolia
| | - Khishigjav Tsogtbaatar
- Institute of Paleontology and Geology, Mongolian Academy of Sciences, Ulaanbaatar, 15160, Mongolia
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18
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Hartman S, Mortimer M, Wahl WR, Lomax DR, Lippincott J, Lovelace DM. A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight. PeerJ 2019; 7:e7247. [PMID: 31333906 PMCID: PMC6626525 DOI: 10.7717/peerj.7247] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 06/01/2019] [Indexed: 11/20/2022] Open
Abstract
The last two decades have seen a remarkable increase in the known diversity of basal avialans and their paravian relatives. The lack of resolution in the relationships of these groups combined with attributing the behavior of specialized taxa to the base of Paraves has clouded interpretations of the origin of avialan flight. Here, we describe Hesperornithoides miessleri gen. et sp. nov., a new paravian theropod from the Morrison Formation (Late Jurassic) of Wyoming, USA, represented by a single adult or subadult specimen comprising a partial, well-preserved skull and postcranial skeleton. Limb proportions firmly establish Hesperornithoides as occupying a terrestrial, non-volant lifestyle. Our phylogenetic analysis emphasizes extensive taxonomic sampling and robust character construction, recovering the new taxon most parsimoniously as a troodontid close to Daliansaurus, Xixiasaurus, and Sinusonasus. Multiple alternative paravian topologies have similar degrees of support, but proposals of basal paravian archaeopterygids, avialan microraptorians, and Rahonavis being closer to Pygostylia than archaeopterygids or unenlagiines are strongly rejected. All parsimonious results support the hypothesis that each early paravian clade was plesiomorphically flightless, raising the possibility that avian flight originated as late as the Late Jurassic or Early Cretaceous.
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Affiliation(s)
- Scott Hartman
- Department of Geoscience, University of Wisconsin-Madison, Madison, WI, USA
| | | | | | - Dean R. Lomax
- School of Earth and Environmental Sciences, The University of Manchester, Manchester, UK
| | | | - David M. Lovelace
- University of Wisconsin Geology Museum, University of Wisconsin-Madison, Madison, WI, USA
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19
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Abstract
Dinosaurs were large-bodied land animals of the Mesozoic that gave rise to birds. They played a fundamental role in structuring Jurassic–Cretaceous ecosystems and had physiology, growth, and reproductive biology unlike those of extant animals. These features have made them targets of theoretical macroecology. Dinosaurs achieved substantial structural diversity, and their fossil record documents the evolutionary assembly of the avian body plan. Phylogeny-based research has allowed new insights into dinosaur macroevolution, including the adaptive landscape of their body size evolution, patterns of species diversification, and the origins of birds and bird-like traits. Nevertheless, much remains unknown due to incompleteness of the fossil record at both local and global scales. This presents major challenges at the frontier of paleobiological research regarding tests of macroecological hypotheses and the effects of dinosaur biology, ecology, and life history on their macroevolution.
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Affiliation(s)
- Roger B.J. Benson
- Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, United Kingdom
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20
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Abstract
Two new species of dinosaur from the mid-Cretaceous of China document previously-unknown stages in the evolutionary transition from primitive Jurassic carnivores to the highly transformed insectivorous alvarezsaurids of the Late Cretaceous.
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Affiliation(s)
- Thomas R Holtz
- Department of Geology, University of Maryland, 8000 Regents Drive, College Park, MD 20742, USA; Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013, USA.
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