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Ribeiro TB, Albuquerque AS, Bragança T, Pereira PVLGC. A lost tooth in the jungle: revisiting the sole dinosaurian record from northern Brazil. AN ACAD BRAS CIENC 2024; 96:e20231180. [PMID: 39140522 DOI: 10.1590/0001-3765202420231180] [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: 10/26/2023] [Accepted: 03/04/2024] [Indexed: 08/15/2024] Open
Abstract
The record of Mesozoic reptiles in the Northern region of Brazil is extremely limited, with the only definite occurrence consisting of two ziphodont teeth recovered from an oil well core in the municipality of Nova Olinda do Norte, Amazonas state, from strata of the Alter do Chão Formation (Cenomanian) of the Amazonas Basin. In this study, we aim to reevaluate MCT.R.514 using the most recent methodologies available for the identification of isolated theropod teeth. The cladistic analyses recovered MCT.R.514 as a possible metriacanthosaurid or non carcharodontosaurid allosauroid while the LDAs showed affinities between the specimen and Abelisauridae, Piatniktzysauridae, and Tyrannosauridae. MCT.R.514 was assigned as an abelisaurid due to its overall morphology that lacked metriacanthosaurid synapomorphies (i.e. spiraling mesial carina, strongly labially displaced distal carina, and well-marked mesiolingual longitudinal groove), while maintaining homoplastic features between both groups (i.e. irregular enamel texture, a lingually biconcave cross section, and a straight distal margin). This, together with a mostly Laurasian distribution of Metriacanthosauridae favors the assignment of MCT.R.514 as an abelisaurid as the most parsimonious hypothesis in this occasion. The identification of the specimen as an abelisaurid further expands the still scarce "Mid'' Cretaceous record of this clade in Brazil.
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Affiliation(s)
- Theo B Ribeiro
- Universidade Federal do Rio de Janeiro, Laboratório de Macrofósseis, Departamento de Geologia, Av. Athos da Silveira Ramos 274, CCMN, 21941-611 Rio de Janeiro, RJ, Brazil
| | - Athirson S Albuquerque
- Universidade Federal do Rio de Janeiro, Laboratório de Macrofósseis, Departamento de Geologia, Av. Athos da Silveira Ramos 274, CCMN, 21941-611 Rio de Janeiro, RJ, Brazil
| | - Thiago Bragança
- Universidade Federal do Rio de Janeiro, Laboratório de Macrofósseis, Departamento de Geologia, Av. Athos da Silveira Ramos 274, CCMN, 21941-611 Rio de Janeiro, RJ, Brazil
| | - Paulo Victor Luiz G C Pereira
- Universidade Federal do Rio de Janeiro, Laboratório de Macrofósseis, Departamento de Geologia, Av. Athos da Silveira Ramos 274, CCMN, 21941-611 Rio de Janeiro, RJ, Brazil
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2
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Pol D, Baiano MA, Černý D, Novas FE, Cerda IA, Pittman M. A new abelisaurid dinosaur from the end Cretaceous of Patagonia and evolutionary rates among the Ceratosauria. Cladistics 2024; 40:307-356. [PMID: 38771085 DOI: 10.1111/cla.12583] [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: 01/05/2024] [Revised: 04/24/2024] [Accepted: 04/24/2024] [Indexed: 05/22/2024] Open
Abstract
Gondwanan dinosaur faunae during the 20 Myr preceding the Cretaceous-Palaeogene (K/Pg) extinction included several lineages that were absent or poorly represented in Laurasian landmasses. Among these, the South American fossil record contains diverse abelisaurids, arguably the most successful groups of carnivorous dinosaurs from Gondwana in the Cretaceous, reaching their highest diversity towards the end of this period. Here we describe Koleken inakayali gen. et sp. n., a new abelisaurid from the La Colonia Formation (Maastrichtian, Upper Cretaceous) of Patagonia. Koleken inakayali is known from several skull bones, an almost complete dorsal series, complete sacrum, several caudal vertebrae, pelvic girdle and almost complete hind limbs. The new abelisaurid shows a unique set of features in the skull and several anatomical differences from Carnotaurus sastrei (the only other abelisaurid known from the La Colonia Formation). Koleken inakayali is retrieved as a brachyrostran abelisaurid, clustered with other South American abelisaurids from the latest Cretaceous (Campanian-Maastrichtian), such as Aucasaurus, Niebla and Carnotaurus. Leveraging our phylogeny estimates, we explore rates of morphological evolution across ceratosaurian lineages, finding them to be particularly high for elaphrosaurine noasaurids and around the base of Abelisauridae, before the Early Cretaceous radiation of the latter clade. The Noasauridae and their sister clade show contrasting patterns of morphological evolution, with noasaurids undergoing an early phase of accelerated evolution of the axial and hind limb skeleton in the Jurassic, and the abelisaurids exhibiting sustained high rates of cranial evolution during the Early Cretaceous. These results provide much needed context for the evolutionary dynamics of ceratosaurian theropods, contributing to broader understanding of macroevolutionary patterns across dinosaurs.
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Affiliation(s)
- Diego Pol
- Museo Argentino de Ciencias Naturales Bernardino Rivadavia, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Mattia Antonio Baiano
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- Área Laboratorio e Investigación, Museo Municipal Ernesto Bachmann, Villa El Chocón, Neuquén, Argentina
- Universidad Nacional de Río Negro (UNRN), General Roca, Río Negro, Argentina
| | - David Černý
- Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA
| | - Fernando E Novas
- Museo Argentino de Ciencias Naturales Bernardino Rivadavia, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Ignacio A Cerda
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Universidad Nacional de Río Negro (UNRN), General Roca, Río Negro, Argentina
- Instituto de Investigación en Paleobiología y Geología (IIPG), General Roca, Río Negro, Argentina
- Museo Provincial Carlos Ameghino, Cipolletti, Río Negro, Argentina
| | - Michael Pittman
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
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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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Hautier L, Gomes Rodrigues H, Ferreira-Cardoso S, Emerling CA, Porcher ML, Asher RJ, Portela Miguez R, Delsuc F. From teeth to pad: tooth loss and development of keratinous structures in sirenians. Proc Biol Sci 2023; 290:20231932. [PMID: 38018114 PMCID: PMC10685118 DOI: 10.1098/rspb.2023.1932] [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: 08/29/2023] [Accepted: 11/03/2023] [Indexed: 11/30/2023] Open
Abstract
Sirenians are a well-known example of morphological adaptation to a shallow-water grazing diet characterized by a modified feeding apparatus and orofacial morphology. Such adaptations were accompanied by an anterior tooth reduction associated with the development of keratinized pads, the evolution of which remains elusive. Among sirenians, the recently extinct Steller's sea cow represents a special case for being completely toothless. Here, we used μ-CT scans of sirenian crania to understand how motor-sensor systems associated with tooth innervation responded to innovations such as keratinized pads and continuous dental replacement. In addition, we surveyed nine genes associated with dental reduction for signatures of loss of function. Our results reveal how patterns of innervation changed with modifications of the dental formula, especially continuous replacement in manatees. Both our morphological and genomic data show that dental development was not completely lost in the edentulous Steller's sea cows. By tracing the phylogenetic history of tooth innervation, we illustrate the role of development in promoting the innervation of keratinized pads, similar to the secondary use of dental canals for innervating neomorphic keratinized structures in other tetrapod groups.
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Affiliation(s)
- Lionel Hautier
- Institut des Sciences de l’Évolution, Université Montpellier, CNRS, IRD, EPHE, Montpellier 34095, France
- Mammal Section, Life Sciences, Vertebrate Division, The Natural History Museum, London, UK
| | - Helder Gomes Rodrigues
- Centre de Recherche en Paléontologie—Paris (CR2P), UMR CNRS 7207, Muséum National d'Histoire Naturelle, Sorbonne Université, Paris, France
| | - Sérgio Ferreira-Cardoso
- Institut des Sciences de l’Évolution, Université Montpellier, CNRS, IRD, EPHE, Montpellier 34095, France
| | | | - Marie-Lou Porcher
- Institut des Sciences de l’Évolution, Université Montpellier, CNRS, IRD, EPHE, Montpellier 34095, France
| | - Robert J. Asher
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Roberto Portela Miguez
- Mammal Section, Life Sciences, Vertebrate Division, The Natural History Museum, London, UK
| | - Frédéric Delsuc
- Institut des Sciences de l’Évolution, Université Montpellier, CNRS, IRD, EPHE, Montpellier 34095, France
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5
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Krishnan A. Biomechanics illuminates form-function relationships in bird bills. J Exp Biol 2023; 226:297128. [PMID: 36912385 DOI: 10.1242/jeb.245171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
Abstract
The field of comparative biomechanics examines how form, mechanical properties and environmental interactions shape the function of biological structures. Biomechanics has advanced by leaps and bounds as rapid technological progress opens up new research horizons. In this Review, I describe how our understanding of the avian bill, a morphologically diverse multifunctional appendage, has been transformed by employing a biomechanical perspective. Across functions from feeding to excavating hollows in trees and as a vocal apparatus, the study of the bill spans both solid and fluid biomechanics, rendering it useful to understand general principles across disciplines. The different shapes of the bill across bird species result in functional and mechanical trade-offs, thus representing a microcosm of many broader form-function questions. Using examples from diverse studies, I discuss how research into bird bills has been shaped over recent decades, and its influence on our understanding of avian ecology and evolution. Next, I examine how bill material properties and geometry influence performance in dietary and non-dietary contexts, simultaneously imposing trade-offs on other functions. Following an examination of the interactions of bills with fluids and their role as part of the vocal apparatus, I end with a discussion of the sensory biomechanics of the bill, focusing specifically on the bill-tip mechanosensory organ. With these case studies, I highlight how this burgeoning and consequential field represents a roadmap for our understanding of the function and evolution of biological structures.
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Affiliation(s)
- Anand Krishnan
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhauri 462066, Madhya Pradesh, India
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6
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Wynd B, Abdala F, Nesbitt SJ. Ontogenetic growth in the crania of Exaeretodon argentinus (Synapsida: Cynodontia) captures a dietary shift. PeerJ 2022; 10:e14196. [PMID: 36299507 PMCID: PMC9590418 DOI: 10.7717/peerj.14196] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 09/15/2022] [Indexed: 01/26/2023] Open
Abstract
Background An ontogenetic niche shift in vertebrates is a common occurrence where ecology shifts with morphological changes throughout growth. How ecology shifts over a vertebrate's lifetime is often reconstructed in extant species-by combining observational and skeletal data from growth series of the same species-because interactions between organisms and their environment can be observed directly. However, reconstructing shifts using extinct vertebrates is difficult and requires well-sampled growth series, specimens with relatively complete preservation, and easily observable skeletal traits associated with ecologies suspected to change throughout growth, such as diet. Methods To reconstruct ecological changes throughout the growth of a stem-mammal, we describe changes associated with dietary ecology in a growth series of crania of the large-bodied (∼2 m in length) and herbivorous form, Exaeretodon argentinus (Cynodontia: Traversodontidae) from the Late Triassic Ischigualasto Formation, San Juan, Argentina. Nearly all specimens were deformed by taphonomic processes, so we reconstructed allometric slope using a generalized linear mixed effects model with distortion as a random effect. Results Under a mixed effects model, we find that throughout growth, E. argentinus reduced the relative length of the palate, postcanine series, orbits, and basicranium, and expanded the relative length of the temporal region and the height of the zygomatic arch. The allometric relationship between the zygomatic arch and temporal region with the total length of the skull approximate the rate of growth for feeding musculature. Based on a higher allometric slope, the zygoma height is growing relatively faster than the length of the temporal region. The higher rate of change in the zygoma may suggest that smaller individuals had a crushing-dominated feeding style that transitioned into a chewing-dominated feeding style in larger individuals, suggesting a dietary shift from possible faunivory to a more plant-dominated diet. Dietary differentiation throughout development is further supported by an increase in sutural complexity and a shift in the orientation of microwear anisotropy between small and large individuals of E. argentinus. A developmental transition in the feeding ecology of E. argentinus is reflective of the reconstructed dietary transition across Gomphodontia, wherein the earliest-diverging species are inferred as omnivorous and the well-nested traversodontids are inferred as herbivorous, potentially suggesting that faunivory in immature individuals of the herbivorous Traversodontidae may be plesiomorphic for the clade.
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Affiliation(s)
- Brenen Wynd
- Department of Geosciences, Virginia Tech, Blacksburg, VA, United States of America
| | - Fernando Abdala
- CONICET-Fundación Miguel Lillo, Unidad Ejecutora Lillo, San Miguel de Tucumán, Tucumán, Argentina
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Sterling J. Nesbitt
- Department of Geosciences, Virginia Tech, Blacksburg, VA, United States of America
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7
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Verrière A, Fröbisch J. Ontogenetic, dietary, and environmental shifts in Mesosauridae. PeerJ 2022; 10:e13866. [PMID: 36132215 PMCID: PMC9484468 DOI: 10.7717/peerj.13866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 07/18/2022] [Indexed: 01/18/2023] Open
Abstract
Mesosaurs are the first secondarily aquatic amniotes and one of the most enigmatic clades of reptiles from the early Permian. They have long puzzled paleontologists with their unique morphologies: possessing an elongated skull with thin needle-like teeth, a long neck, large webbed hindlimbs, banana-shaped pachyosteosclerotic ribs, and a long tail. Here, we look at a large dataset of morphometric measurements from 270 mesosaur specimens in collections around the world. These measurements characterize skull, tooth, and limb proportions and their variation with size. This data presents evidence of surprising ontogenetic changes in these animals as well as new insights into their taxonomy. Our results support the recent hypothesis that Mesosaurus tenuidens is the only valid species within Mesosauridae and suggest that "Stereosternum tumidum" and "Brazilosaurus sanpauloensis" represent immature stages or incomplete specimens of Mesosaurus by showing that all three species occupy an incomplete portion of the overall size range of mesosaurs. Under the single-species hypothesis, we highlight a number of ontogenetic trends: (1) a reduction in skull length accompanied by an elongation of the snout within the skull, (2) an elongation of teeth, (3) a reduction in hind limb length, and (4) a reduction in manus length. Concurrent with these changes, we hypothesize that mesosaurs went through a progressive ecological shift during their growth, with juveniles being more common in shallow water deposits, whereas large adults are more frequent in pelagic sediments. These parallel changes suggest that mesosaurs underwent a diet and lifestyle transition during ontogeny, from an active predatory lifestyle as juveniles to a more filter-feeding diet as adults. We propose that this change in lifestyle and environments may have been driven by the pursuit of different food sources, but a better understanding of the Irati Sea fauna will be necessary to obtain a more definitive answer to the question of young mesosaur diet.
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Affiliation(s)
- Antoine Verrière
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung und Institut für Biologie, Berlin, Germany
| | - Jörg Fröbisch
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung und Institut für Biologie, Berlin, Germany
- Institut für Biologie, Humboldt-Universität zu Berlin, Berlin, Germany
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8
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A large Megaraptoridae (Theropoda: Coelurosauria) from Upper Cretaceous (Maastrichtian) of Patagonia, Argentina. Sci Rep 2022; 12:6318. [PMID: 35474310 PMCID: PMC9042913 DOI: 10.1038/s41598-022-09272-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 03/11/2022] [Indexed: 11/22/2022] Open
Abstract
Megaraptora is a theropod clade known from former Gondwana landmasses and Asia. Most members of the clade are known from the Early to Late Cretaceous (Barremian–Santonian), with Maastrichtian megaraptorans known only from isolated and poorly informative remains. The aim of the present contribution is to describe a partial skeleton of a megaraptorid from Maastrichtian beds in Santa Cruz Province, Argentina. This new specimen is the most informative megaraptoran known from Maastrichtian age, and is herein described as a new taxon. Phylogenetic analysis nested the new taxon together with other South American megaraptorans in a monophyletic clade, whereas Australian and Asian members constitute successive stem groups. South American forms differ from more basal megaraptorans in several anatomical features and in being much larger and more robustly built.
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9
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Hendrickx C, Bell PR, Pittman M, Milner ARC, Cuesta E, O'Connor J, Loewen M, Currie PJ, Mateus O, Kaye TG, Delcourt R. Morphology and distribution of scales, dermal ossifications, and other non-feather integumentary structures in non-avialan theropod dinosaurs. Biol Rev Camb Philos Soc 2022; 97:960-1004. [PMID: 34991180 DOI: 10.1111/brv.12829] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 12/10/2021] [Accepted: 12/14/2021] [Indexed: 12/14/2022]
Abstract
Modern birds are typified by the presence of feathers, complex evolutionary innovations that were already widespread in the group of theropod dinosaurs (Maniraptoriformes) that include crown Aves. Squamous or scaly reptilian-like skin is, however, considered the plesiomorphic condition for theropods and dinosaurs more broadly. Here, we review the morphology and distribution of non-feathered integumentary structures in non-avialan theropods, covering squamous skin and naked skin as well as dermal ossifications. The integumentary record of non-averostran theropods is limited to tracks, which ubiquitously show a covering of tiny reticulate scales on the plantar surface of the pes. This is consistent also with younger averostran body fossils, which confirm an arthral arrangement of the digital pads. Among averostrans, squamous skin is confirmed in Ceratosauria (Carnotaurus), Allosauroidea (Allosaurus, Concavenator, Lourinhanosaurus), Compsognathidae (Juravenator), and Tyrannosauroidea (Santanaraptor, Albertosaurus, Daspletosaurus, Gorgosaurus, Tarbosaurus, Tyrannosaurus), whereas dermal ossifications consisting of sagittate and mosaic osteoderms are restricted to Ceratosaurus. Naked, non-scale bearing skin is found in the contentious tetanuran Sciurumimus, ornithomimosaurians (Ornithomimus) and possibly tyrannosauroids (Santanaraptor), and also on the patagia of scansoriopterygids (Ambopteryx, Yi). Scales are surprisingly conservative among non-avialan theropods compared to some dinosaurian groups (e.g. hadrosaurids); however, the limited preservation of tegument on most specimens hinders further interrogation. Scale patterns vary among and/or within body regions in Carnotaurus, Concavenator and Juravenator, and include polarised, snake-like ventral scales on the tail of the latter two genera. Unusual but more uniformly distributed patterning also occurs in Tyrannosaurus, whereas feature scales are present only in Albertosaurus and Carnotaurus. Few theropods currently show compelling evidence for the co-occurrence of scales and feathers (e.g. Juravenator, Sinornithosaurus), although reticulate scales were probably retained on the mani and pedes of many theropods with a heavy plumage. Feathers and filamentous structures appear to have replaced widespread scaly integuments in maniraptorans. Theropod skin, and that of dinosaurs more broadly, remains a virtually untapped area of study and the appropriation of commonly used techniques in other palaeontological fields to the study of skin holds great promise for future insights into the biology, taphonomy and relationships of these extinct animals.
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Affiliation(s)
- Christophe Hendrickx
- Unidad Ejecutora Lillo, CONICET-Fundación Miguel Lillo, 251 Miguel Lillo, San Miguel de Tucumán, Tucumán, 4000, Argentina
| | - Phil R Bell
- School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, Australia
| | - Michael Pittman
- Vertebrate Palaeontology Laboratory, Department of Earth Sciences, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China.,Department of Earth Sciences, University College London, WC1E 6BT, United Kingdom
| | - Andrew R C Milner
- St. George Dinosaur Discovery Site at Johnson Farm, 2180 East Riverside Drive, St. George, UT, U.S.A
| | - Elena Cuesta
- Bayerische Staatssammlung für Paläontologie und Geologie, Richard-Wagner-Str. 10, Munich, 80333, Germany
| | - Jingmai O'Connor
- Field Museum of Natural History, 1400 S Lake Shore Drive, Chicago, IL, 60605, U.S.A
| | - Mark Loewen
- Department of Geology and Geophysics, University of Utah, Frederick Albert Sutton Building, 115 South 1460 East, Salt Lake City, UT, 84112, U.S.A.,Natural History Museum of Utah, 301 Wakara Way, Salt Lake City, UT, 84108, U.S.A
| | - Philip J Currie
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Octávio Mateus
- GeoBioTec, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal.,Museu da Lourinhã, 95 Rua João Luis de Moura, Lourinhã, 2530-158, Portugal
| | - Thomas G Kaye
- Foundation for Scientific Advancement, 7023 Alhambra Dr., Sierra Vista, AZ, 85650, U.S.A
| | - Rafael Delcourt
- Universidade Estadual de Campinas (UNICAMP), Instituto de Geociências, Cidade Universitária, Rua Carlos Gomes, 250, Campinas, SP, 13083-855, Brazil
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10
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Cadena EA, Link A, Cooke SB, Stroik LK, Vanegas AF, Tallman M. New insights on the anatomy and ontogeny of the largest extinct freshwater turtles. Heliyon 2021; 7:e08591. [PMID: 35005268 PMCID: PMC8717240 DOI: 10.1016/j.heliyon.2021.e08591] [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: 10/28/2021] [Revised: 11/30/2021] [Accepted: 12/09/2021] [Indexed: 11/26/2022] Open
Abstract
There are many questions regarding the largest freshwater turtle that ever existed, including how its morphology changed during its ontogeny and how a single ecosystem was able to support more than one group of giant turtles. Here, we report the first individual preserving an associated skull and shell for Stupendemys geographica (currently the largest known side-necked turtle) and a nearly complete skull of Caninemys tridentata found in Miocene rocks of the Tatacoa Desert in Colombia. These two specimens indicate that more than two large freshwater turtle species shared a single ecosystem during the middle Miocene in northern South America. We also show the changes in the shell and scutes that occurred along the ontogeny of S. geographica, including a flattening of the carapace, constriction of the vertebral scutes, and increase in the height and thickness of the nuchal upturn wall; some of these changes are also evident in extant representatives of Podocnemididae, and have implications for a better understanding of their phylogeny.
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Affiliation(s)
- Edwin-Alberto Cadena
- Universidad del Rosario, Facultad de Ciencias Naturales, Grupo de Investigación Paleontología Neotropical Tradicional y Molecular (PaleoNeo), Bogotá, Colombia
- Smithsonian Tropical Research Institute, Panamá, Panama
| | - Andrés Link
- Departamento de Ciencias Biológicas, Universidad de Los Andes, Bogotá, Colombia
| | - Siobhán B. Cooke
- Center for Functional Anatomy and Evolution, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Laura K. Stroik
- Department of Biomedical Sciences, Grand Valley State University, Allendale, MI, USA
| | | | - Melissa Tallman
- Department of Biomedical Sciences, Grand Valley State University, Allendale, MI, USA
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11
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de Souza GA, Soares MB, Weinschütz LC, Wilner E, Lopes RT, de Araújo OMO, Kellner AWA. The first edentulous ceratosaur from South America. Sci Rep 2021; 11:22281. [PMID: 34795306 PMCID: PMC8602317 DOI: 10.1038/s41598-021-01312-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 10/18/2021] [Indexed: 11/09/2022] Open
Abstract
The recognition of ontogenetic edentulism in the Jurassic noasaurid Limusaurus inextricabilis shed new light on the dietary diversity within Ceratosauria, a stem lineage of non-avian theropod dinosaurs known for peculiar craniomandibular adaptations. Until now, edentulism in Ceratosauria was exclusive to adult individuals of Limusaurus. Here, an exceptionally complete skeleton of a new toothless ceratosaur, Berthasaura leopoldinae gen. et sp. nov., is described from the Cretaceous aeolian sandstones of the Bauru Basin, Southern Brazil. The specimen resembles adult individuals of Limusaurus by the absence of teeth but based on the unfused condition of several elements (e.g., skull, vertebral column) it clearly represents an ontogenetically immature individual, indicating that it might never have had teeth. The phylogenetic analysis performed here has nested Berthasaura leopoldinae as an early-divergent Noasauridae, not closely related to Limusaurus. It represents the most complete non-avian theropod from the Brazilian Cretaceous and preserves the most complete noasaurid axial series known so far. Moreover, the new taxon exhibits many novel osteological features, uncommon in non-avian theropods, and unprecedented even among South American ceratosaurs. These include not only toothless jaws but also a premaxilla with cutting occlusal edge, and a slightly downturned rostral tip. This indicate that B. leopoldinae unlikely had the same diet as other ceratosaurs, most being regarded as carnivorous. As the ontogenetically more mature specimens of Limusaurus, Berthasaura might have been herbivorous or at least omnivorous, corroborating with an early evolutionary divergence of noasaurids from the ceratosaurian bauplan by disparate feeding modes.
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Affiliation(s)
- Geovane Alves de Souza
- Programa de Pós-graduação em Zoologia (PPGZoo), Museu Nacional/Universidade Federal do Rio de Janeiro, Quinta da Boa Vista s/n, São Cristóvão, Rio de Janeiro, RJ, 20940-040, Brazil
- Laboratório de Sistemática e Tafonomia de Vertebrados Fósseis (LAPUG), Departamento de Geologia e Paleontologia, Museu Nacional/Universidade Federal do Rio de Janeiro, Quinta da Boa Vista s/n, São Cristóvão, Rio de Janeiro, RJ, 20940-040, Brazil
| | - Marina Bento Soares
- Laboratório de Sistemática e Tafonomia de Vertebrados Fósseis (LAPUG), Departamento de Geologia e Paleontologia, Museu Nacional/Universidade Federal do Rio de Janeiro, Quinta da Boa Vista s/n, São Cristóvão, Rio de Janeiro, RJ, 20940-040, Brazil
| | - Luiz Carlos Weinschütz
- Centro Paleontológico da Universidade do Contestado (CENPALEO), Universidade do Contestado, Av. Presidente Nereu Ramos, 1071, Jardim Moinho, Mafra, SC, 89.306-076, Brazil
| | - Everton Wilner
- Centro Paleontológico da Universidade do Contestado (CENPALEO), Universidade do Contestado, Av. Presidente Nereu Ramos, 1071, Jardim Moinho, Mafra, SC, 89.306-076, Brazil
| | - Ricardo Tadeu Lopes
- Laboratório de Instrumentação Nuclear (LIN), Programa de Engenharia Nuclear/COPPE, Universidade Federal do Rio de Janeiro, Av. Horácio Macedo, Cidade Universitária, Rio de Janeiro, RJ, 21941-450, Brazil
| | - Olga Maria Oliveira de Araújo
- Laboratório de Instrumentação Nuclear (LIN), Programa de Engenharia Nuclear/COPPE, Universidade Federal do Rio de Janeiro, Av. Horácio Macedo, Cidade Universitária, Rio de Janeiro, RJ, 21941-450, Brazil
| | - Alexander Wilhelm Armin Kellner
- Laboratório de Sistemática e Tafonomia de Vertebrados Fósseis (LAPUG), Departamento de Geologia e Paleontologia, Museu Nacional/Universidade Federal do Rio de Janeiro, Quinta da Boa Vista s/n, São Cristóvão, Rio de Janeiro, RJ, 20940-040, Brazil.
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12
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Spiekman SNF, Ezcurra MD, Butler RJ, Fraser NC, Maidment SCR. Pendraig milnerae, a new small-sized coelophysoid theropod from the Late Triassic of Wales. ROYAL SOCIETY OPEN SCIENCE 2021; 8:210915. [PMID: 34754500 PMCID: PMC8493203 DOI: 10.1098/rsos.210915] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 09/07/2021] [Indexed: 06/13/2023]
Abstract
We describe a new small-bodied coelophysoid theropod dinosaur, Pendraig milnerae gen. et sp. nov, from the Late Triassic fissure fill deposits of Pant-y-ffynnon in southern Wales. The species is represented by the holotype, consisting of an articulated pelvic girdle, sacrum and posterior dorsal vertebrae, and an associated left femur, and by two referred specimens, comprising an isolated dorsal vertebra and a partial left ischium. Our phylogenetic analysis recovers P. milnerae as a non-coelophysid coelophysoid theropod, representing the first-named unambiguous theropod from the Triassic of the UK. Recently, it has been suggested that Pant-y-ffynnon and other nearby Late Triassic to Early Jurassic fissure fill faunas might have been subjected to insular dwarfism. To test this hypothesis for P. milnerae, we performed an ancestral state reconstruction analysis of body size in early neotheropods. Although our results indicate that a reduced body size is autapomorphic for P. milnerae, some other coelophysoid taxa show a similar size reduction, and there is, therefore, ambiguous evidence to indicate that this species was subjected to dwarfism. Our analyses further indicate that, in contrast with averostran-line neotheropods, which increased in body size during the Triassic, coelophysoids underwent a small body size decrease early in their evolution.
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Affiliation(s)
- Stephan N. F. Spiekman
- Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Martín D. Ezcurra
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
- Sección Paleontología de Vertebrados, CONICET-Museo Argentino de Ciencias Naturales, Ángel Gallardo 470, C1405DJR Buenos Aires, Argentina
| | - Richard J. Butler
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | | | - Susannah C. R. Maidment
- Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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13
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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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14
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Heckert AB, Nesbitt SJ, Stocker MR, Schneider VP, Hoffman DK, Zimmer BW. A new short-faced archosauriform from the Upper Triassic Placerias/Downs' quarry complex, Arizona, USA, expands the morphological diversity of the Triassic archosauriform radiation. Naturwissenschaften 2021; 108:32. [PMID: 34213630 PMCID: PMC8253714 DOI: 10.1007/s00114-021-01733-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 03/21/2021] [Accepted: 04/12/2021] [Indexed: 11/25/2022]
Abstract
The Placerias/Downs' Quarry complex in eastern Arizona, USA, is the most diverse Upper Triassic vertebrate locality known. We report a new short-faced archosauriform, Syntomiprosopus sucherorum gen. et sp. nov., represented by four incomplete mandibles, that expands that diversity with a morphology unique among Late Triassic archosauriforms. The most distinctive feature of Syntomiprosopus gen. nov. is its anteroposteriorly short, robust mandible with 3-4 anterior, a larger caniniform, and 1-3 "postcanine" alveoli. The size and shape of the alveoli and the preserved tips of replacement teeth preclude assignment to any taxon known only from teeth. Additional autapomorphies of S. sucherorum gen. et sp. nov. include a large fossa associated with the mandibular fenestra, an interdigitating suture of the surangular with the dentary, fine texture ornamenting the medial surface of the splenial, and a surangular ridge that completes a 90° arc. The external surfaces of the mandibles bear shallow, densely packed, irregular, fine pits and narrow, arcuate grooves. This combination of character states allows an archosauriform assignment; however, an associated and similarly sized braincase indicates that Syntomiprosopus n. gen. may represent previously unsampled disparity in early-diverging crocodylomorphs. The Placerias Quarry is Adamanian (Norian, maximum depositional age ~219 Ma), and this specimen appears to be an early example of shortening of the skull, which occurs later in diverse archosaur lineages, including the Late Cretaceous crocodyliform Simosuchus. This is another case where Triassic archosauriforms occupied morphospace converged upon by other archosaurs later in the Mesozoic and further demonstrates that even well-sampled localities can yield new taxa.
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Affiliation(s)
- Andrew B Heckert
- Department of Geological & Environmental Sciences, Appalachian State University, ASU Box 32067, Boone, NC, 28607, USA.
- North Carolina Museum of Natural Sciences, Raleigh, NC, USA.
| | - Sterling J Nesbitt
- North Carolina Museum of Natural Sciences, Raleigh, NC, USA
- Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Michelle R Stocker
- North Carolina Museum of Natural Sciences, Raleigh, NC, USA
- Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | | | - Devin K Hoffman
- Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Brian W Zimmer
- Department of Geological & Environmental Sciences, Appalachian State University, ASU Box 32067, Boone, NC, 28607, USA
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15
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Wynd BM, Uyeda JC, Nesbitt SJ. Including Distorted Specimens in Allometric Studies: Linear Mixed Models Account for Deformation. Integr Org Biol 2021; 3:obab017. [PMID: 34377943 PMCID: PMC8341891 DOI: 10.1093/iob/obab017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Allometry—patterns of relative change in body parts—is a staple for examining how clades exhibit scaling patterns representative of evolutionary constraint on phenotype, or quantifying patterns of ontogenetic growth within a species. Reconstructing allometries from ontogenetic series is one of the few methods available to reconstruct growth in fossil specimens. However, many fossil specimens are deformed (twisted, flattened, and displaced bones) during fossilization, changing their original morphology in unpredictable and sometimes undecipherable ways. To mitigate against post burial changes, paleontologists typically remove clearly distorted measurements from analyses. However, this can potentially remove evidence of individual variation and limits the number of samples amenable to study, which can negatively impact allometric reconstructions. Ordinary least squares (OLS) regression and major axis regression are common methods for estimating allometry, but they assume constant levels of residual variation across specimens, which is unlikely to be true when including both distorted and undistorted specimens. Alternatively, a generalized linear mixed model (GLMM) can attribute additional variation in a model (e.g., fixed or random effects). We performed a simulation study based on an empirical analysis of the extinct cynodont, Exaeretodon argentinus, to test the efficacy of a GLMM on allometric data. We found that GLMMs estimate the allometry using a full dataset better than simply using only non-distorted data. We apply our approach on two empirical datasets, cranial measurements of actual specimens of E. argentinus (n = 16) and femoral measurements of the dinosaur Tawa hallae (n = 26). Taken together, our study suggests that a GLMM is better able to reconstruct patterns of allometry over an OLS in datasets comprised of extinct forms and should be standard protocol for anyone using distorted specimens.
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Affiliation(s)
- B M Wynd
- Department of Geosciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - J C Uyeda
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - S J Nesbitt
- Department of Geosciences, Virginia Tech, Blacksburg, VA 24061, USA
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16
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To KHT, O’Brien HD, Stocker MR, Gignac PM. Cranial Musculoskeletal Description of Black-Throated Finch (Aves: Passeriformes: Estrildidae) with DiceCT. INTEGRATIVE ORGANISMAL BIOLOGY (OXFORD, ENGLAND) 2021; 3:obab007. [PMID: 34841194 PMCID: PMC8613829 DOI: 10.1093/iob/obab007] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Synopsis Dietary requirements and acquisition strategies change throughout ontogeny across various clades of tetrapods, including birds. For example, birds hatch with combinations of various behavioral, physiological, and morphological factors that place them on an altricial-precocial spectrum. Passeriformes (=songbirds) in particular, a family constituting approximately more than half of known bird species, displays the most drastic difference between hatchling and adults in each of these aspects of their feeding biology. How the shift in dietary resource acquisition is managed during ontogeny alongside its relationship to the morphology of the feeding apparatus has been largely understudied within birds. Such efforts have been hampered partly due to the small size of many birds and the diminutive jaw musculature they employ. In this study, we used standard and diffusible iodine-based contrast-enhanced computed tomography in conjunction with digital dissection to quantify and describe the cranial musculature of the Black-throated Finch (Poephila cincta) at fledgling and adult stages. Our results reveal that in both the fledgling and the adult, cranial musculature shows clear and complex partitioning in the Musculus adductor mandibulae externus that is consistent with other families within Passeriformes. We quantified jaw-muscle sizes and found that the adult showed a decrease in muscle mass in comparison to the fledgling individual. We propose that this could be the result of low sample size or a physiological effect of parental care in Passeriformes. Our study shows that high-resolution visualization techniques are informative at revealing morphological discrepancies for studies that involve small specimens such as Passeriformes especially with careful specimen selection criteria.
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Affiliation(s)
| | - H D O’Brien
- Department of Anatomy and Cell Biology, Oklahoma State University Center
for Health Sciences, 1111 W 17th Street, Tulsa,
OK 74107, USA
| | - M R Stocker
- Department of Geosciences, Virginia Tech, Derring
Hall, 926 W Campus Dr, Blacksburg, VA 24060, USA
| | - P M Gignac
- Department of Anatomy and Cell Biology, Oklahoma State University Center
for Health Sciences, 1111 W 17th Street, Tulsa,
OK 74107, USA
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17
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Chen CK, Juan WT, Liang YC, Wu P, Chuong CM. Making region-specific integumentary organs in birds: evolution and modifications. Curr Opin Genet Dev 2021; 69:103-111. [PMID: 33780743 DOI: 10.1016/j.gde.2021.02.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 02/20/2021] [Accepted: 02/24/2021] [Indexed: 11/16/2022]
Abstract
Birds are the most diversified terrestrial vertebrates due to highly diverse integumentary organs that enable robust adaptability to various eco-spaces. Here we show that this complexity is built upon multi-level regional specifications. Across-the-body (macro-) specification includes the evolution of beaks and feathers as new integumentary organs that are formed with regional specificity. Within-an-organ (micro-) specification involves further modifications of organ shapes. We review recent progress in elucidating the molecular mechanisms underlying feather diversification as an example. (1) β-Keratin gene clusters are regulated by typical enhancers or high order chromatin looping to achieve macro- and micro-level regional specification, respectively. (2) Multi-level symmetry-breaking of feather branches confers new functional forms. (3) Complex color patterns are produced by combinations of macro-patterning and micro-patterning processes. The integration of these findings provides new insights toward the principle of making a robustly adaptive bio-interface.
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Affiliation(s)
- Chih-Kuan Chen
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA; The IEGG and Animal Biotechnology Center, National Chung Hsing University, Taichung 402, Taiwan
| | - Wen-Tau Juan
- Integrative Stem Cell Center, China Medical University Hospital, Taichung 40447, Taiwan
| | - Ya-Chen Liang
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Ping Wu
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Cheng-Ming Chuong
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.
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18
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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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19
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Bonatto Paese CL, Hawkins MB, Brugmann SA, Harris MP. Atavisms in the avian hindlimb and early developmental polarity of the limb. Dev Dyn 2021; 250:1358-1367. [PMID: 33605505 DOI: 10.1002/dvdy.318] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 02/10/2021] [Accepted: 02/15/2021] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND The naturally occurring chicken mutant talpid2 (ta2 ), best known for its limb and craniofacial defects, has long served as a valuable tool for developmental biologists studying growth and patterning of craniofacial structures and the limb. The mutant provides a unique tool to examine the molecular and cellular processes regulating limb development. RESULTS This mutant also provides unique insights into the evolution of developmental genetic programs. Previous work defined the appearance of atavistic dentition in ta2 embryos. Herein we describe the appearance of ancestral characters of the hindlimb in embryonic ta2 chicken embryos. CONCLUSION As the ta2 phenotype arises as a result of mutation in C2CD3 and disrupted cilia function, this mutant provides genetic and developmental insight into the causes of asymmetry in the limb and also a model for the evolution of the avian hindlimb.
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Affiliation(s)
- Christian L Bonatto Paese
- Division of Developmental Biology, Department of Pediatrics; Division of Plastic Surgery, Department of Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.,Shriners Hospital, Cincinnati, Ohio, USA
| | - Michael Brent Hawkins
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.,Department of Orthopedic Research, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Samantha A Brugmann
- Division of Developmental Biology, Department of Pediatrics; Division of Plastic Surgery, Department of Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.,Shriners Hospital, Cincinnati, Ohio, USA
| | - Matthew P Harris
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.,Department of Orthopedic Research, Boston Children's Hospital, Boston, Massachusetts, USA
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20
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Griffin CT, Stocker MR, Colleary C, Stefanic CM, Lessner EJ, Riegler M, Formoso K, Koeller K, Nesbitt SJ. Assessing ontogenetic maturity in extinct saurian reptiles. Biol Rev Camb Philos Soc 2020; 96:470-525. [PMID: 33289322 DOI: 10.1111/brv.12666] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 10/09/2020] [Accepted: 10/28/2020] [Indexed: 01/06/2023]
Abstract
Morphology forms the most fundamental level of data in vertebrate palaeontology because it is through interpretations of morphology that taxa are identified, creating the basis for broad evolutionary and palaeobiological hypotheses. Assessing maturity is one of the most basic aspects of morphological interpretation and provides the means to study the evolution of ontogenetic changes, population structure and palaeoecology, life-history strategies, and heterochrony along evolutionary lineages that would otherwise be lost to time. Saurian reptiles (the least-inclusive clade containing Lepidosauria and Archosauria) have remained an incredibly diverse, numerous, and disparate clade through their ~260-million-year history. Because of the great disparity in this group, assessing maturity of saurian reptiles is difficult, fraught with methodological and terminological ambiguity. We compiled a novel database of literature, assembling >900 individual instances of saurian maturity assessment, to examine critically how saurian maturity has been diagnosed. We review the often inexact and inconsistent terminology used in saurian maturity assessment (e.g. 'juvenile', 'mature') and provide routes for better clarity and cross-study coherence. We describe the various methods that have been used to assess maturity in every major saurian group, integrating data from both extant and extinct taxa to give a full account of the current state of the field and providing method-specific pitfalls, best practices, and fruitful directions for future research. We recommend that a new standard subsection, 'Ontogenetic Assessment', be added to the Systematic Palaeontology portions of descriptive studies to provide explicit ontogenetic diagnoses with clear criteria. Because the utility of different ontogenetic criteria is highly subclade dependent among saurians, even for widely used methods (e.g. neurocentral suture fusion), we recommend that phylogenetic context, preferably in the form of a phylogenetic bracket, be used to justify the use of a maturity assessment method. Different methods should be used in conjunction as independent lines of evidence when assessing maturity, instead of an ontogenetic diagnosis resting entirely on a single criterion, which is common in the literature. Critically, there is a need for data from extant taxa with well-represented growth series to be integrated with the fossil record to ground maturity assessments of extinct taxa in well-constrained, empirically tested methods.
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Affiliation(s)
- Christopher T Griffin
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
| | - Michelle R Stocker
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
| | - Caitlin Colleary
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Vertebrate Paleontology, Cleveland Museum of Natural History, 1 Wade Oval Drive, Cleveland, OH, 44106, U.S.A
| | - Candice M Stefanic
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Anatomical Sciences, Stony Brook University, 100 Nicolls Road, Stony Brook, NY, 11794, U.S.A
| | - Emily J Lessner
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Pathology and Anatomical Sciences, University of Missouri, 1 Hospital Drive, Columbia, MO, 65212, U.S.A
| | - Mitchell Riegler
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Geological Sciences, University of Florida, 241 Williamson Hall, Gainesville, FL, 32611, U.S.A
| | - Kiersten Formoso
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Earth Sciences, University of Southern California, 3651 Trousdale Pkwy, Los Angeles, CA, 90089, U.S.A
- Dinosaur Institute, Natural History Museum of Los Angeles County, 900 W Exposition Boulevard, Los Angeles, CA, 90007, U.S.A
| | - Krista Koeller
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Biology, University of Florida, 220 Bartram Hall, Gainesville, FL, 32611, U.S.A
| | - Sterling J Nesbitt
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
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21
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de Souza GA, Soares MB, Brum AS, Zucolotto M, Sayão JM, Weinschütz LC, Kellner AWA. Osteohistology and growth dynamics of the Brazilian noasaurid Vespersaurus paranaensis Langer et al., 2019 (Theropoda: Abelisauroidea). PeerJ 2020; 8:e9771. [PMID: 32983636 PMCID: PMC7500327 DOI: 10.7717/peerj.9771] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 07/30/2020] [Indexed: 12/24/2022] Open
Abstract
Although the knowledge of bone histology of non-avian theropods has advanced considerably in recent decades, data about the bone tissue patterns, growth dynamics and ontogeny of some taxa such as abelisauroids are still limited. Here we describe the bone microstructure and growth dynamics of the Brazilian noasaurine Vespersaurus paranaensis using five femora and six tibiae and quantify the annual growth marks through retrocalculation of missing ones to estimate ontogenetic ages. The femoral series comprises four femoral histological classes (FHC I-IV), varying from two annuli or LAGs to seven LAGs. Femora show that sexual maturity was achieved around the seventh to tenth year of life, whereas the tibiae suggest it was earlier (around three to five years old). Tibiae represent three histological classes (THC I-III) displaying from three to nine LAGs. Two tibiae (THC III) exhibit an external fundamental system indicating that these specimens reached full skeletal size. The heterogeneous maturity observed in Vespersaurus hind limb bones could result from differential allometry scaling between femora and tibiae length with the body length. The predominant parallel-fibered bone matrix suggests that Vespersaurus grew more slowly than most theropods, including other abelisauroids, in a pattern shared with the noasaurines Masiakasaurus knopfleri from Madagascar and CPPLIP 1490 from Brazil. This deviation from the typical theropod growth pattern may be mainly correlated with small body size, but also may related to resource limitation imposed by the arid climate prevailing in southwestern Gondwana during Cretaceous. Moreover, given the ecological and phylogenetic similarities among these taxa, such features would probably be apomorphic within Noasauridae.
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Affiliation(s)
- Geovane Alves de Souza
- Programa de Pós-Graduação em Zoologia (PPGZoo), Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Marina Bento Soares
- Laboratory of Systematics and Taphonomy of Fossil Vertebrates, Departamento de Geologia e Paleontologia, Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Arthur Souza Brum
- Programa de Pós-Graduação em Zoologia (PPGZoo), Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Maria Zucolotto
- Departamento de Geologia e Paleontologia, Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Juliana M Sayão
- Núcleo de Biologia, Centro Acadêmico de Vitória, Universidade Federal de Pernambuco, Vitória de Santo Antão, Pernambuco, Brazil
| | | | - Alexander W A Kellner
- Laboratory of Systematics and Taphonomy of Fossil Vertebrates, Departamento de Geologia e Paleontologia, Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
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22
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Ezcurra MD, Butler RJ, Maidment SCR, Sansom IJ, Meade LE, Radley JD. A revision of the early neotheropod genus Sarcosaurus from the Early Jurassic (Hettangian–Sinemurian) of central England. Zool J Linn Soc 2020. [DOI: 10.1093/zoolinnean/zlaa054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
Neotheropoda represents the main evolutionary radiation of predatory dinosaurs and its oldest records come from Upper Triassic rocks (c. 219 Mya). The Early Jurassic record of Neotheropoda is taxonomically richer and geographically more widespread than that of the Late Triassic. The Lower Jurassic (upper Hettangian–lower Sinemurian) rocks of central England have yielded three neotheropod specimens that have been assigned to two species within the genus Sarcosaurus, S. woodi (type species) and S. andrewsi. These species have received little attention in discussions of the early evolution of Neotheropoda and recently have been considered as nomina dubia. Here, we provide a detailed redescription of one of these specimens (WARMS G667–690) and reassess the taxonomy and phylogenetic relationships of the genus Sarcosaurus. We propose that the three neotheropod specimens from the Early Jurassic of central England represent a single valid species, S. woodi. The second species of the genus, ‘S. andrewsi’, is a subjective junior synonym of the former. A quantitative phylogenetic analysis of early theropods recovered S. woodi as one of the closest sister-taxa to Averostra and provides new information on the sequence of character state transformations in the lead up to the phylogenetic split between Ceratosauria and Tetanurae.
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Affiliation(s)
- Martín D Ezcurra
- Sección Paleontología de Vertebrados, CONICET-Museo Argentino de Ciencias Naturales, Buenos Aires, Argentina
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Richard J Butler
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Susannah C R Maidment
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
- Department of Earth Sciences, Natural History Museum, London, UK
| | - Ivan J Sansom
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Luke E Meade
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Jonathan D Radley
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
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23
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Birch SA, Smith ET, Bell PR. Noasaurids are a component of the Australian 'mid'-Cretaceous theropod fauna. Sci Rep 2020; 10:1428. [PMID: 31996712 PMCID: PMC6989633 DOI: 10.1038/s41598-020-57667-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 12/26/2019] [Indexed: 12/12/2022] Open
Abstract
The diversity of Australia's theropod fauna from the 'mid'-Cretaceous (Albian-Cenomanian) is distinctly biased towards the medium-sized megaraptorids, despite the preponderance of abelisauroids in the younger but latitudinally equivalent Patagonian theropod fauna. Here, we present new evidence for the presence of ceratosaurian, and specifically abelisauroid, theropods from the Cenomanian Griman Creek Formation of Lightning Ridge, New South Wales. A partial cervical vertebra is described that bears a mediolaterally concave ventral surface of the centrum delimited by sharp ventrolateral ridges that contact the parapophyses. Among theropods, this feature has been reported only in a cervical vertebra attributed to the noasaurid Noasaurus. We also reappraise evidence recently cited against the ceratosaurian interpretation of a recently described astragalocalcaneum from the upper Barremian-lower Aptian San Remo Member of the upper Strzelecki Group in Victoria. Inclusion of the Lightning Ridge cervical vertebra and Victorian astragalocalcaneum into a revised phylogenetic analysis focused on elucidating ceratosaurian affinities reveals support for placement of both specimens within Noasauridae, which among other characters is diagnosed by the presence of a medial eminence on the ascending process of the astragalus. The Lightning Ridge and Victorian specimens simultaneously represent the first noasaurids reported from Australia and the astragalocalcaneum is considered the earliest known example of a noasaurid in the world to date. The recognition of Australian noasaurids further indicates a more widespread Gondwanan distribution of the clade outside of South America, Madagascar and India consistent with the timing of the fragmentation of the supercontinent.
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Affiliation(s)
- Sienna A Birch
- School of environmental and Rural Science, University of New England, Armidale, NSW, Australia.
| | | | - Phil R Bell
- School of environmental and Rural Science, University of New England, Armidale, NSW, Australia
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24
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A new possible megalosauroid theropod from the Middle Jurassic Xintiangou Formation of Chongqing, People's Republic of China and its implication for early tetanuran evolution. Sci Rep 2020; 10:139. [PMID: 31924836 PMCID: PMC6954265 DOI: 10.1038/s41598-019-56959-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 11/25/2019] [Indexed: 11/08/2022] Open
Abstract
Tetanurae is a special group of theropod dinosaurs that originated by the late Early Jurassic. It includes several early-diverging groups of generally large-bodied predators (megalosauroids, allosauroids, tyrannosauroid coelurosaurs) as well as morphologically disparate small-bodied coelurosaurs, including birds. Aspects of the evolutionary history of tetanurans remain contested, including the topology of their deep phylogenetic divergences (among Megalosauroidea, Allosauroidea and Coelurosauria). We report a new theropod, Yunyangosaurus puanensis gen. et sp. nov., based on a fragmentary specimen recovered from the Middle Jurassic Xintiangou Formation of Chongqing, southwestern China. It shares several features uniquely with some megalosauroids (the clade of megalosaurids + spinosaurids + piatnitzkysaurids), such as prominent rims around the anterior articular surfaces of cervical centra and bifurcated anterior dorsal neural spines (present in piatnitzkysaurids). Nevertheless, it also shows several features that are rare or absent among megalosauroids and more crownward tetanurans, including prominent spinopostyzgopophyseal laminae (also present in non-tetanurans and metriacanthosaurid allosauroids), flat anterior articular surfaces of the cervical centra (also present in piatnitzkysaurids and some earlier-diverging tetanurans), and the presence of a posterior pneumatic foramen or fossa (absent in most tetanurans, but sporadically present in some cervical vertebrae of piatnitzkysaurids). Yunyangosaurus therefore presents a combination of derived and apparently primitive character states that are not seen in other theropods. This suggests that patterns of morphological evolution associated with deep tetanuran divergences were more complex than currently recognized, with implications for understanding the character evolution in theropods.
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25
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Button DJ, Zanno LE. Repeated Evolution of Divergent Modes of Herbivory in Non-avian Dinosaurs. Curr Biol 2020; 30:158-168.e4. [DOI: 10.1016/j.cub.2019.10.050] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 09/08/2019] [Accepted: 10/25/2019] [Indexed: 01/13/2023]
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26
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Ma W, Brusatte SL, Lü J, Sakamoto M. The skull evolution of oviraptorosaurian dinosaurs: the role of niche partitioning in diversification. J Evol Biol 2019; 33:178-188. [PMID: 31622509 DOI: 10.1111/jeb.13557] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 09/28/2019] [Accepted: 10/04/2019] [Indexed: 11/30/2022]
Abstract
Oviraptorosaurs are bird-like theropod dinosaurs that thrived in the final pre-extinction ecosystems during the latest Cretaceous, and the beaked, toothless skulls of derived species are regarded as some of the most peculiar among dinosaurs. Their aberrant morphologies are hypothesized to have been caused by rapid evolution triggered by an ecological/biological driver, but little is known about how their skull shapes and functional abilities diversified. Here, we use quantitative techniques to study oviraptorosaur skull form and mandibular function. We demonstrate that the snout is particularly variable, that mandibular form and upper/lower beak form are significantly correlated with phylogeny, and that there is a strong and significant correlation between mandibular function and mandible/lower beak shape, suggesting a form-function association. The form-function relationship and phylogenetic signals, along with a moderate allometric signal in lower beak form, indicate that similar mechanisms governed beak shape in oviraptorosaurs and extant birds. The two derived oviraptorosaur clades, oviraptorids and caenagnathids, are significantly separated in morphospace and functional space, indicating that they partitioned niches. Oviraptorids coexisting in the same ecosystem are also widely spread in morphological and functional space, suggesting that they finely partitioned feeding niches, whereas caenagnathids exhibit extreme disparity in beak size. The diversity of skull form and function was likely key to the diversification and evolutionary success of oviraptorosaurs in the latest Cretaceous.
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Affiliation(s)
- Waisum Ma
- School of GeoSciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Stephen L Brusatte
- School of GeoSciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Junchang Lü
- Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China
| | - Manabu Sakamoto
- School of Biological Sciences, University of Reading, Reading, United Kingdom
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27
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Langer MC, Martins NDO, Manzig PC, Ferreira GDS, Marsola JCDA, Fortes E, Lima R, Sant'ana LCF, Vidal LDS, Lorençato RHDS, Ezcurra MD. A new desert-dwelling dinosaur (Theropoda, Noasaurinae) from the Cretaceous of south Brazil. Sci Rep 2019; 9:9379. [PMID: 31243312 PMCID: PMC6594977 DOI: 10.1038/s41598-019-45306-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 06/04/2019] [Indexed: 11/09/2022] Open
Abstract
Noasaurines form an enigmatic group of small-bodied predatory theropod dinosaurs known from the Late Cretaceous of Gondwana. They are relatively rare, with notable records in Argentina and Madagascar, and possible remains reported for Brazil, India, and continental Africa. In south-central Brazil, the deposits of the Bauru Basin have yielded a rich tetrapod fauna, which is concentrated in the Bauru Group. The mainly aeolian deposits of the Caiuá Group, on the contrary, bear a scarce fossil record composed only of lizards, turtles, and pterosaurs. Here, we describe the first dinosaur of the Caiuá Group, which also represents the best-preserved theropod of the entire Bauru Basin known to date. The recovered skeletal parts (vertebrae, girdles, limbs, and scarce cranial elements) show that the new taxon was just over 1 m long, with a unique anatomy among theropods. The shafts of its metatarsals II and IV are very lateromedially compressed, as are the blade-like ungual phalanges of the respective digits. This implies that the new taxon could have been functionally monodactyl, with a main central weight-bearing digit, flanked by neighbouring elements positioned very close to digit III or even held free of the ground. Such anatomical adaptation is formerly unrecorded among archosaurs, but has been previously inferred from footprints of the same stratigraphic unit that yielded the new dinosaur. A phylogenetic analysis nests the new taxon within the Noasaurinae clade, which is unresolved because of the multiple alternative positions that Noasaurus leali can acquire in the optimal trees. The exclusion of the latter form results in positioning the new dinosaur as the sister-taxon of the Argentinean Velocisaurus unicus.
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Affiliation(s)
- Max Cardoso Langer
- Laboratório de Paleontologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto/SP, Brazil.
| | - Neurides de Oliveira Martins
- Museu de Paleontologia de Cruzeiro do Oeste, Rua João Ormino de Rezende, 686, 87400-000, Cruzeiro do Oeste/PR, Brazil
- Centro de Estudos Paleontologicos, Ambientais e Culturais (Cepac), Rua Edmundo Mercer Junior, 1308, 87400-000, Cruzeiro do Oeste/PR, Brazil
| | - Paulo César Manzig
- Museu de Paleontologia de Cruzeiro do Oeste, Rua João Ormino de Rezende, 686, 87400-000, Cruzeiro do Oeste/PR, Brazil
| | - Gabriel de Souza Ferreira
- Laboratório de Paleontologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto/SP, Brazil
| | - Júlio César de Almeida Marsola
- Laboratório de Paleontologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto/SP, Brazil
| | - Edison Fortes
- Programa de Pós-Graduação em Geografia (PGE), Universidade Estadual de Maringá, Avenida Colombo, 5790, 87020-900, Maringá/PR, Brazil
| | - Rosana Lima
- Programa de Pós-Graduação em Geografia (PGE), Universidade Estadual de Maringá, Avenida Colombo, 5790, 87020-900, Maringá/PR, Brazil
- Grupo de Estudos Multidisciplinares do Ambiente (GEMA), Universidade Estadual de Maringá, Avenida Colombo, 5790, 87020-900, Maringá/PR, Brazil
| | - Lucas Cesar Frediani Sant'ana
- Programa de Pós-Graduação em Geografia (PGE), Universidade Estadual de Maringá, Avenida Colombo, 5790, 87020-900, Maringá/PR, Brazil
| | - Luciano da Silva Vidal
- Laboratório de Macrofósseis, Universidade Federal do Rio de Janeiro, Av. Athos da Silveira Ramos, 274, 21941-611, Rio de Janeiro/RJ, Brazil
| | | | - Martín Daniel Ezcurra
- Sección Paleontología de Vertebrados, CONICET-Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Avenida Ángel Gallardo, 470, C1405DJR, Buenos Aires, Argentina
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28
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Yang TR, Sander PM. The origin of the bird's beak: new insights from dinosaur incubation periods. Biol Lett 2019; 14:rsbl.2018.0090. [PMID: 29794006 DOI: 10.1098/rsbl.2018.0090] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 04/30/2018] [Indexed: 11/12/2022] Open
Abstract
The toothless beak of modern birds was considered as an adaption for feeding ecology; however, several recent studies suggested that developmental factors are also responsible for the toothless beak. Neontological and palaeontological studies have progressively uncovered how birds evolved toothless beaks and suggested that the multiple occurrences of complete edentulism in non-avian dinosaurs were the result of selection for specialized diets. Although developmental biology and ecological factors are not mutually exclusive, the conventional hypothesis that ecological factors account for the toothless beak appears insufficient. A recent study on dinosaur incubation period using embryonic teeth posited that tooth formation rate limits developmental speed, constraining toothed dinosaur incubation to slow reptilian rates. We suggest that selection for tooth loss was a side effect of selection for fast embryo growth and thus shorter incubation. This observation would also explain the multiple occurrences of tooth loss and beaks in non-avian dinosaur taxa crownward of Tyrannosaurus Whereas our hypothesis is an observation without any experimental supports, more studies of gene regulation of tooth formation in embryos would allow testing for the trade-off between incubation period and tooth development.
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Affiliation(s)
- Tzu-Ruei Yang
- Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 8, 53115 Bonn, Germany
| | - P Martin Sander
- Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 8, 53115 Bonn, Germany.,Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, CA 90007, USA
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29
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Zheng X, O'Connor JK, Wang X, Wang Y, Zhou Z. Reinterpretation of a previously described Jehol bird clarifies early trophic evolution in the Ornithuromorpha. Proc Biol Sci 2019; 285:rspb.2017.2494. [PMID: 29386367 DOI: 10.1098/rspb.2017.2494] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 01/10/2018] [Indexed: 11/12/2022] Open
Abstract
STM35-3 from the Yixian Formation is the only Early Cretaceous ornithuromorph preserving direct evidence of granivory. The crop contains numerous seeds and the preservation of gastroliths presumably within the ventriculus indicates this diet was paired with the presence of a gastric mill as in living granivorous birds. STM35-3 was originally referred to Hongshanornis longicresta, member of a diverse clade of small, basal ornithuromorphs with elongate hindlimbs known as the Hongshanornithidae. Hindlimb proportions suggest that hongshanornithids were wading birds, an ecological inference somewhat in conflict with direct evidence suggesting Hongshanornis fed on seeds. However, close inspection of STM35-3 reveals that the specimen represents a new species not closely related to hongshanornithids, distinguished by large forelimbs that exceed the length of the hindlimbs, robust and narrow coracoids, and a delicate edentulous rostrum. By contrast, all hongshanornithids have hindlimbs that far exceed the length of the forelimbs, coracoids with wide sternal margins, and small teeth throughout the upper and lower jaws. Reinterpretation of this new taxon, Eogranivora edentulata gen. et sp. nov, helps to clarify trophic driven patterns of tooth loss within the Ornithuromorpha. Apparent loss of the hallux may represent the first such occurrence in a Mesozoic bird and suggests a highly terrestrial lifestyle.
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Affiliation(s)
- Xiaoting Zheng
- Institute of Geology and Paleontology, Linyi University, Linyi, Shandong 276000, People's Republic of China.,Tianyu Natural History Museum of Shandong, Pingyi, Shandong 273300, People's Republic of China
| | - Jingmai K O'Connor
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, People's Republic of China
| | - Xiaoli Wang
- Institute of Geology and Paleontology, Linyi University, Linyi, Shandong 276000, People's Republic of China.,Tianyu Natural History Museum of Shandong, Pingyi, Shandong 273300, People's Republic of China
| | - Yan Wang
- Institute of Geology and Paleontology, Linyi University, Linyi, Shandong 276000, People's Republic of China.,Tianyu Natural History Museum of Shandong, Pingyi, Shandong 273300, People's Republic of China
| | - Zhonghe Zhou
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, People's Republic of China
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30
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Dal Sasso C, Maganuco S, Cau A. The oldest ceratosaurian (Dinosauria: Theropoda), from the Lower Jurassic of Italy, sheds light on the evolution of the three-fingered hand of birds. PeerJ 2018; 6:e5976. [PMID: 30588396 PMCID: PMC6304160 DOI: 10.7717/peerj.5976] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 10/22/2018] [Indexed: 12/18/2022] Open
Abstract
The homology of the tridactyl hand of birds is a still debated subject, with both paleontological and developmental evidence used in support of alternative identity patterns in the avian fingers. With its simplified phalangeal morphology, the Late Jurassic ceratosaurian Limusaurus has been argued to support a II-III-IV digital identity in birds and a complex pattern of homeotic transformations in three-fingered (tetanuran) theropods. We report a new large-bodied theropod, Saltriovenator zanellai gen. et sp. nov., based on a partial skeleton from the marine Saltrio Formation (Sinemurian, lowermost Jurassic) of Lombardy (Northern Italy). Taphonomical analyses show bone bioerosion by marine invertebrates (first record for dinosaurian remains) and suggest a complex history for the carcass before being deposited on a well-oxygenated and well-illuminated sea bottom. Saltriovenator shows a mosaic of features seen in four-fingered theropods and in basal tetanurans. Phylogenetic analysis supports sister taxon relationships between the new Italian theropod and the younger Early Jurassic Berberosaurus from Morocco, in a lineage which is the basalmost of Ceratosauria. Compared to the atrophied hand of later members of Ceratosauria, Saltriovenator demonstrates that a fully functional hand, well-adapted for struggling and grasping, was primitively present in ceratosaurians. Ancestral state reconstruction along the avian stem supports 2-3-4-1-X and 2-3-4-0-X as the manual phalangeal formulae at the roots of Ceratosauria and Tetanurae, confirming the I-II-III pattern in the homology of the avian fingers. Accordingly, the peculiar hand of Limusaurus represents a derived condition restricted to late-diverging ceratosaurians and cannot help in elucidating the origin of the three-fingered condition of tetanurans. The evolution of the tridactyl hand of birds is explained by step-wise lateral simplification among non-tetanuran theropod dinosaurs, followed by a single primary axis shift from digit position 4 to 3 at the root of Tetanurae once the fourth finger was completely lost, which allowed independent losses of the vestigial fourth metacarpal among allosaurians, tyrannosauroids, and maniraptoromorphs. With an estimated body length of 7.5 m, Saltriovenator is the largest and most robust theropod from the Early Jurassic, pre-dating the occurrence in theropods of a body mass approaching 1,000 Kg by over 25 My. The radiation of larger and relatively stockier averostran theropods earlier than previously known may represent one of the factors that ignited the trend toward gigantism in Early Jurassic sauropods.
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Affiliation(s)
| | | | - Andrea Cau
- Museo Geologico "Giovanni Capellini", Bologna, Italy
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31
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The Smallest Diplodocid Skull Reveals Cranial Ontogeny and Growth-Related Dietary Changes in the Largest Dinosaurs. Sci Rep 2018; 8:14341. [PMID: 30310088 PMCID: PMC6181913 DOI: 10.1038/s41598-018-32620-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 08/24/2018] [Indexed: 12/04/2022] Open
Abstract
Sauropod dinosaurs were the largest terrestrial vertebrates; yet despite a robust global fossil record, the paucity of cranial remains complicates attempts to understand their paleobiology. An assemblage of small diplodocid sauropods from the Upper Jurassic Morrison Formation of Montana, USA, has produced the smallest diplodocid skull yet discovered. The ~24 cm long skull is referred to cf. Diplodocus based on the presence of several cranial and vertebral characters. This specimen enhances known features of early diplodocid ontogeny including a short snout with narrow-crowned teeth limited to the anterior portion of the jaws and more spatulate teeth posteriorly. The combination of size plus basal and derived character expression seen here further emphasizes caution when naming new taxa displaying the same, as these may be indicative of immaturity. This young diplodocid reveals that cranial modifications occurred throughout growth, providing evidence for ontogenetic dietary partitioning and recapitulation of ancestral morphologies.
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32
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Ceratosaur palaeobiology: new insights on evolution and ecology of the southern rulers. Sci Rep 2018; 8:9730. [PMID: 29950661 PMCID: PMC6021374 DOI: 10.1038/s41598-018-28154-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 06/12/2018] [Indexed: 11/28/2022] Open
Abstract
Ceratosaur theropods ruled the Southern Hemisphere until the end of the Late Cretaceous. However, their origin was earlier, during the Early Jurassic, a fact which allowed the group to reach great morphological diversity. The body plans of the two main branches (Noasauridae and new name Etrigansauria: Ceratosauridae + Abelisauridae) are quite different; nevertheless, they are sister taxa. Abelisaurids have lost the ability to grasp in the most derived taxa, but the reduced forelimb might have had some display function. The ontogenetic changes are well known in Limusaurus which lost all their teeth and probably changed the dietary preference at maturity. The results presented here suggest that abelisaurids had different soft tissues on the skull. These tissues might have been associated with evolution of a strong cervicocephalic complex and should have allowed derived taxa (e.g. Majungasaurus and Carnotaurus) to have low-displacement headbutting matches. The ability to live in different semi-arid environment plus high morphological disparity allowed the ceratosaurs to become an evolutionary success.
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Moore AJ, Mo J, Clark JM, Xu X. Cranial anatomy of Bellusaurus sui (Dinosauria: Eusauropoda) from the Middle-Late Jurassic Shishugou Formation of northwest China and a review of sauropod cranial ontogeny. PeerJ 2018; 6:e4881. [PMID: 29868283 PMCID: PMC5985764 DOI: 10.7717/peerj.4881] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 05/10/2018] [Indexed: 11/20/2022] Open
Abstract
Bellusaurus sui is an enigmatic sauropod dinosaur from the Middle-Late Jurassic Shishugou Formation of northwest China. Bellusaurus is known from a monospecific bonebed preserving elements from more than a dozen juvenile individuals, including numerous bones of the skull, providing rare insight into the cranial anatomy of juvenile sauropods. Here, we present a comprehensive description of the cranial anatomy of Bellusaurus, supplementing the holotypic cranial material with additional elements recovered from recent joint Sino-American field expeditions. Bellusaurus is diagnosed by several unique autapomorphies, including a neurovascular foramen piercing the ascending process of the maxilla at midheight, the frontal process of the nasal extending farther posteriorly onto the frontal than the prefrontal, and U-shaped medial and lateral notches in the posterior margin of the ventral process of the squamosal. Several features identified here, including a preantorbital opening in the maxilla, a stepped dorsal margin of the vomerine process of the pterygoid, and the partitioning of the dorsal midline endocranial fossae associated with the dural venous sinuses into anterior and posterior components by a transverse ridge of the parietal, are consistent with recent phylogenetic hypotheses that recover Bellusaurus as a basal macronarian or close relative of Neosauropoda. We review the current state of knowledge of sauropod cranial ontogeny, placing several aspects of the cranial anatomy of Bellusaurus in an ontogenetic context and providing explicit hypotheses of ontogenetic transformations that can be tested by future discoveries of ontogenetic variants of sauropod skulls. While scoring ontogenetically variable characters as unknown may help to alleviate the biasing effects of ontogeny on the phylogenetic position of juvenile specimens, we caution that this approach may remove phylogenetically informative character information, and argue that inference methods that are known to be less sensitive to homoplasy than equal weights parsimony (i.e., implied weights parsimony; Bayesian approaches) should also be employed.
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Affiliation(s)
- Andrew J Moore
- Department of Biological Sciences, George Washington University, Washington, DC, USA
| | - Jinyou Mo
- Natural History Museum of Guangxi Zhuang Autonomous Region, Nanning, China
| | - James M Clark
- Department of Biological Sciences, George Washington University, Washington, DC, USA
| | - Xing Xu
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
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Abstract
Understanding ontogenetic patterns is important in vertebrate paleontology because the assessed skeletal maturity of an individual often has implications for paleobiogeography, species synonymy, paleobiology, and body size evolution of major clades. Further, for many groups the only means of confidently determining ontogenetic status of an organism is through the destructive process of histological sampling. Although the ontogenetic patterns of Late Jurassic and Cretaceous dinosaurs are better understood, knowledge of the ontogeny of the earliest dinosaurs is relatively poor because most species-level growth series known from these groups are small (usually, maximum of n ~ 5) and incomplete. To investigate the morphological changes that occur during ontogeny in early dinosaurs, I used ontogenetic sequence analysis (OSA) to reconstruct developmental sequences of morphological changes in the postcranial ontogeny of the early theropods Coelophysis bauri and Megapnosaurus rhodesiensis, both of which are known from large sample sizes (n = 174 and 182, respectively). I found a large amount of sequence polymorphism (i.e. intraspecific variation in developmental patterns) in both taxa, and especially in C. bauri, which possesses this variation in every element analyzed. Megapnosaurus rhodesiensis is similar, but it possesses no variation in the sequence of development of ontogenetic characters in the tibia and tarsus. Despite the large amount of variation in development, many characters occur consistently earlier or later in ontogeny and could therefore be important morphological features for assessing the relative maturity of other early theropods. Additionally, there is a phylogenetic signal to the order in which homologous characters appear in ontogeny, with homologous characters appearing earlier or later in developmental sequences of early theropods and the close relatives of dinosaurs, silesaurids. Many of these morphological features are important characters for the reconstruction of archosaurian phylogeny (e.g. trochanteric shelf). Because these features vary in presence or appearance with ontogeny, these characters should be used with caution when undertaking phylogenetic analyses in these groups, since a specimen may possess certain character states owing to ontogenetic stage, not evolutionary relationships.
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Affiliation(s)
- C. T. Griffin
- Department of GeosciencesVirginia TechBlacksburgVAUSA
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35
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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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36
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Wang S, Zhang Q, Yang R. Reevaluation of the Dentary Structures of Caenagnathid Oviraptorosaurs (Dinosauria, Theropoda). Sci Rep 2018; 8:391. [PMID: 29321606 PMCID: PMC5762635 DOI: 10.1038/s41598-017-18703-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 12/15/2017] [Indexed: 12/28/2022] Open
Abstract
Among the characters of caenagnathid oviraptorosaurians, the lateral occlusal grooves and ridges on the occlusal surface of the jaw bones often receive special attention. Recent studies demonstrated that ontogenetic edentulism is present in caenagnathids, and therefore the lateral occlusal grooves and ridges are vestigial alveoli and interdental septa, respectively. In the present paper, the dentary structures of caenagnathids were reevaluated based on CT images of Caenagnathiasia sp. IVPP V20377. Several previously unknown features including crateriform vestigial alveoli, the morphology of the dentary interior hollow space, and the paired blind tubes beneath the dentary symphyseal shelf are recognized. Current lines of evidence suggest different jaw bone morphologies are likely produced by various tooth reduction patterns, which indicates ontogenetic dietary shift, if once presented in caenagnathids and Sapeornis, may have been different from the condition seen in Limusaurus. The 3D images of dentary interior spaces suggest that while tooth reduction progresses, the empty alveoli are partially modified into structures accommodating blood vessels that nourish the rhamphotheca, probably representing a functional compensation for the insufficient blood supply in toothed jaw bones.
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Affiliation(s)
- Shuo Wang
- Laboratory of Vertebrate Evolution, College of Life Science, Capital Normal University, Beijing, 100048, China. .,State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, 210008, China.
| | - Qiyue Zhang
- Laboratory of Vertebrate Evolution, College of Life Science, Capital Normal University, Beijing, 100048, China
| | - Rui Yang
- Laboratory of Vertebrate Evolution, College of Life Science, Capital Normal University, Beijing, 100048, China
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Wang S, Stiegler J, Wu P, Chuong CM, Hu D, Balanoff A, Zhou Y, Xu X. Heterochronic truncation of odontogenesis in theropod dinosaurs provides insight into the macroevolution of avian beaks. Proc Natl Acad Sci U S A 2017; 114:10930-10935. [PMID: 28973883 PMCID: PMC5642708 DOI: 10.1073/pnas.1708023114] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Beaks are innovative structures characterizing numerous tetrapod lineages, including birds, but little is known about how developmental processes influenced the macroevolution of these important structures. Here we provide evidence of ontogenetic vestigialization of alveoli in two lineages of theropod dinosaurs and show that these are transitional phenotypes in the evolution of beaks. One of the smallest known caenagnathid oviraptorosaurs and a small specimen of the Early Cretaceous bird Sapeornis both possess shallow, empty vestiges of dentary alveoli. In both individuals, the system of vestiges connects via foramina with a dorsally closed canal homologous to alveoli. Similar morphologies are present in Limusaurus, a beaked theropod that becomes edentulous during ontogeny; and an analysis of neontological and paleontological evidence shows that ontogenetic reduction of the dentition is a relatively common phenomenon in vertebrate evolution. Based on these lines of evidence, we propose that progressively earlier postnatal and embryonic truncation of odontogenesis corresponds with expansion of rostral keratin associated with the caruncle, and these progenesis and peramorphosis heterochronies combine to drive the evolution of edentulous beaks in nonavian theropods and birds. Following initial apomorphic expansion of rostral keratinized epithelia in perinatal toothed theropods, beaks appear to inhibit odontogenesis as they grow postnatally, resulting in a sequence of common morphologies. This sequence is shifted earlier in development through phylogeny until dentition is absent at hatching, and odontogenesis is inhibited by beak formation in ovo.
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Affiliation(s)
- Shuo Wang
- Laboratory of Vertebrate Evolution, College of Life Science, Capital Normal University, Beijing 100048, China;
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, 210008, China
| | - Josef Stiegler
- Department of Biological Sciences, The George Washington University, Washington, DC 20052
| | - Ping Wu
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
| | - Cheng-Ming Chuong
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
| | - Dongyu Hu
- Paleontological Institute of Shenyang Normal University, Paleontological Museum of Liaoning, Key Laboratory for Evolution of Past Life in Northeast Asia, Ministry of Land and Resources, Shenyang 110034, China
| | - Amy Balanoff
- Center for Functional Anatomy and Evolution, Johns Hopkins University, Baltimore, MD 21205
| | - Yachun Zhou
- Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xing Xu
- Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
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