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MacDougall MJ, Jannel A, Henrici AC, Berman DS, Sumida SS, Martens T, Fröbisch NB, Fröbisch J. A new recumbirostran 'microsaur' from the lower Permian Bromacker locality, Thuringia, Germany, and its fossorial adaptations. Sci Rep 2024; 14:4200. [PMID: 38378723 PMCID: PMC10879142 DOI: 10.1038/s41598-023-46581-3] [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: 07/21/2023] [Accepted: 11/02/2023] [Indexed: 02/22/2024] Open
Abstract
Several recumbirostran 'microsaurs' are known from early Permian sites across Germany, including the Tambach Formation in Thuringia, central Germany. The only 'microsaur' thus far described from the Tambach Formation was the ostodolepid recumbirostran Tambaroter carrolli. However, there is also the documented presence of an undescribed recumbirostran 'microsaur' at the well-known Bromacker locality. The Bromacker locality is highly recognized and best known for its very diverse and extremely well-preserved terrestrial tetrapod assemblage combined with the co-occurrence of an exceptional vertebrate ichnofossil record. Here we describe a second new recumbirostran taxon from the Tambach Formation, which is also the first from the Bromacker locality itself. Phylogenetic analysis indicates that the new taxon, Bromerpeton subcolossus gen. et sp. nov., is a brachystelechid recumbirostran, a group also known elsewhere in Germany. The following features differentiate Bromerpeton from the other members of the clade: the presence of 13 maxillary teeth, narrow postorbitals that do not substantially contribute to the postorbital region of the skull, the frontal does not contribute to the orbital margin, and the presence of five manual digits. This new recumbirostran 'microsaur' further adds to the unique ecosystem that is preserved at the Bromacker locality, granting us a better understanding of what was living underfoot the larger more well-known animals at the locality. Likewise, it expands our understanding of the evolution of recumbirostran 'microsaurs', especially with regards to digit and limb reduction within the clade.
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Affiliation(s)
- Mark J MacDougall
- Museum für Naturkunde Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstraße 43, 10115, Berlin, Germany.
| | - Andréas Jannel
- Museum für Naturkunde Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstraße 43, 10115, Berlin, Germany
| | - Amy C Henrici
- Carnegie Museum of Natural History, Pittsburgh, PA, USA
| | | | | | | | - Nadia B Fröbisch
- Museum für Naturkunde Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstraße 43, 10115, Berlin, Germany
- Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Jörg Fröbisch
- Museum für Naturkunde Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstraße 43, 10115, Berlin, Germany
- Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
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2
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Gee BM, Kufner AM. Revision of the Late Triassic metoposaurid “ Metoposaurus” bakeri (Amphibia: Temnospondyli) from Texas, USA and a phylogenetic analysis of the Metoposauridae. PeerJ 2022. [DOI: 10.7717/peerj.14065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Metoposaurids are a clade of large-bodied temnospondyls commonly found in non-marine Late Triassic deposits across northern Pangea. Three taxa are known from North America: Anaschisma browni, Apachesaurus gregorii, and “Metoposaurus” bakeri. While the osteology of most metoposaurids has been recently revised, that of a few taxa, including “Metoposaurus” bakeri remains poorly characterized. This taxon was formally described in 1931 as “Buettneria bakeri,” and its taxonomy has remained in flux ever since then. “Metoposaurus” bakeri is the earliest appearing metoposaurid in North America (Carnian of Texas), and Metoposaurus has frequently been utilized as an index taxon of the Otischalkian estimated holochron (‘land vertebrate faunachron’) and for biostratigraphic correlations with other geographic regions. The taxonomy of this species is therefore relevant for both taxonomic experts and biostratigraphers. Here we redescribe all material from the type locality of “M.” bakeri, the Elkins Place bone bed, and perform a phylogenetic analysis using a revised matrix assembled from several previous studies. Anatomical comparisons and phylogenetic analyses do not support placement in either Metoposaurus, a taxon otherwise only found in Europe, or Anaschisma, the only other large-bodied taxon from North America. Therefore, we erect a new genus, Buettnererpeton gen. nov., to accommodate this species. Metoposaurus is consequently absent from North America, and this genus cannot be used in global biostratigraphy. Phylogenetic analyses provide evidence that the phylogeny of the Metoposauridae remains extremely labile, with drastic differences in topological resolution and structure being linked to just a handful of characters and scores. Metoposaurids’ morphological conservatism and the increased recognition of intraspecific variation thus continue to be major confounds to elucidating the evolutionary history of this clade.
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Affiliation(s)
- Bryan M. Gee
- Burke Museum and Department of Biology, University of Washington, Seattle, Washington, United States
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Aaron M. Kufner
- Department of Geoscience, University of Wisconsin, Madison, Wisconsin, United States
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3
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Convergence, divergence, and macroevolutionary constraint as revealed by anatomical network analysis of the squamate skull, with an emphasis on snakes. Sci Rep 2022; 12:14469. [PMID: 36008512 PMCID: PMC9411180 DOI: 10.1038/s41598-022-18649-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: 05/10/2022] [Accepted: 08/17/2022] [Indexed: 11/08/2022] Open
Abstract
Traditionally considered the earliest-diverging group of snakes, scolecophidians are central to major evolutionary paradigms regarding squamate feeding mechanisms and the ecological origins of snakes. However, quantitative analyses of these phenomena remain scarce. Herein, we therefore assess skull modularity in squamates via anatomical network analysis, focusing on the interplay between ‘microstomy’ (small-gaped feeding), fossoriality, and miniaturization in scolecophidians. Our analyses reveal distinctive patterns of jaw connectivity across purported ‘microstomatans’, thus supporting a more complex scenario of jaw evolution than traditionally portrayed. We also find that fossoriality and miniaturization each define a similar region of topospace (i.e., connectivity-based morphospace), with their combined influence imposing further evolutionary constraint on skull architecture. These results ultimately indicate convergence among scolecophidians, refuting widespread perspectives of these snakes as fundamentally plesiomorphic and morphologically homogeneous. This network-based examination of skull modularity—the first of its kind for snakes, and one of the first to analyze squamates—thus provides key insights into macroevolutionary trends among squamates, with particular implications for snake origins and evolution.
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4
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Jia J, Li G, Gao KQ. Palatal morphology predicts the paleobiology of early salamanders. eLife 2022; 11:76864. [PMID: 35575462 PMCID: PMC9170251 DOI: 10.7554/elife.76864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 05/15/2022] [Indexed: 11/13/2022] Open
Abstract
Ecological preferences and life history strategies have enormous impacts on the evolution and phenotypic diversity of salamanders, but the yet established reliable ecological indicators from bony skeletons hinder investigations into the paleobiology of early salamanders. Here, we statistically demonstrate by using time-calibrated cladograms and geometric morphometric analysis on 71 specimens in 36 species, that both the shape of the palate and many non-shape covariates particularly associated with vomerine teeth are ecologically informative in early stem- and basal crown-group salamanders. Disparity patterns within the morphospace of the palate in ecological preferences, life history strategies, and taxonomic affiliations were analyzed in detail, and evolutionary rates and ancestral states of the palate were reconstructed. Our results show that the palate is heavily impacted by convergence constrained by feeding mechanisms and also exhibits clear stepwise evolutionary patterns with alternative phenotypic configurations to cope with similar functional demand. Salamanders are diversified ecologically before the Middle Jurassic and achieved all their present ecological preferences in the Early Cretaceous. Our results reveal that the last common ancestor of all salamanders share with other modern amphibians a unified biphasic ecological preference, and metamorphosis is significant in the expansion of ecomorphospace of the palate in early salamanders.
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Affiliation(s)
- Jia Jia
- Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, Canada
| | - Guangzhao Li
- Department of Microbiology, Immunology and Tropical Medicine, George Washington University, Washington, United States
| | - Ke-Qin Gao
- School of Earth and Space Sciences, Peking University, Beijing, China
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5
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Bona P, Fernandez Blanco MV, Ezcurra MD, von Baczko MB, Desojo JB, Pol D. On the homology of crocodylian post-dentary bones and their macroevolution throughout Pseudosuchia. Anat Rec (Hoboken) 2022; 305:2980-3001. [PMID: 35202518 DOI: 10.1002/ar.24873] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 10/29/2021] [Accepted: 11/19/2021] [Indexed: 12/24/2022]
Abstract
The lower jaw of early tetrapods is composed of several intramembranous ossifications. However, a tendency toward the independent reduction of the number of bones has been observed in the mandible of mammals, lepidosaurs, turtles, crocodiles, and birds. Regarding archosaurs, the coronoid and prearticular bones are interpreted to be lost during the evolution of stem-birds and stem-crocodiles, respectively, but the homology of the post-dentary bones retained in living pseudosuchians remains unclear. Here, we combine paleontological and embryological evidence to explore in detail the homology of the crocodylian post-dentary bones. We study the mandible embryogenesis on a sample of 71 embryos of Caiman and compare this pattern with the mandibular transformations observed across pseudosuchian evolution. In the pre-hatching ontogeny of caimans, at least five intramembranous ossification centers are formed along the margins of the internal mandibular fenestra (perifenestral centers) and, subsequently, merge to form the coronoid (three intramembranous centers), angular (one intramembranous center), and articular (one intramembranous and one chondral center). In the fossil record, an independent prearticular is lost around the base of Mesoeucrocodylia (optimized as reappearing in Thalattosuchia if they are placed within Neosuchia), and the coronoid is apomorphically lost in notosuchians. The integration of embryological and paleontological data indicates that most perifenestral centers are involved in the origin of the prearticular of non-mesoeucrocodylian pseudosuchians. These centers are rearranged during the evolution to contribute to different post-dentary bones in mesoeucrocodylians bolstering the idea that the coronoid and the articular of Crocodylia are not completely homologous to those of other diapsids.
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Affiliation(s)
- Paula Bona
- División Paleontología Vertebrados, Anexo II Laboratorios del Museo de La Plata, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - María Victoria Fernandez Blanco
- División Paleontología Vertebrados, Anexo II Laboratorios del Museo de La Plata, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Martín Daniel Ezcurra
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.,Sección Paleontología de Vertebrados, CONICET-Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Buenos Aires, Argentina
| | - María Belén von Baczko
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.,Sección Paleontología de Vertebrados, CONICET-Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Buenos Aires, Argentina
| | - Julia Brenda Desojo
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.,División Paleontología Vertebrados, Museo de La Plata, Universidad Nacional de La Plata, Buenos Aires, Argentina
| | - Diego Pol
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.,Museo Paleontológico Egidio Feruglio, Trelew, Argentina
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6
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Gee BM. Returning to the roots: resolution, reproducibility, and robusticity in the phylogenetic inference of Dissorophidae (Amphibia: Temnospondyli). PeerJ 2021; 9:e12423. [PMID: 34820181 PMCID: PMC8582317 DOI: 10.7717/peerj.12423] [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: 03/24/2021] [Accepted: 10/11/2021] [Indexed: 11/22/2022] Open
Abstract
The phylogenetic relationships of most Paleozoic tetrapod clades remain poorly resolved, which is variably attributed to a lack of study, the limitations of inference from phenotypic data, and constant revision of best practices. While refinement of phylogenetic methods continues to be important, any phylogenetic analysis is inherently constrained by the underlying dataset that it analyzes. Therefore, it becomes equally important to assess the accuracy of these datasets, especially when a select few are repeatedly propagated. While repeat analyses of these datasets may appear to constitute a working consensus, they are not in fact independent, and it becomes especially important to evaluate the accuracy of these datasets in order to assess whether a seeming consensus is robust. Here I address the phylogeny of the Dissorophidae, a speciose clade of Paleozoic temnospondyls. This group is an ideal case study among temnospondyls for exploring phylogenetic methods and datasets because it has been extensively studied (eight phylogenetic studies to date) but with most (six studies) using a single matrix that has been propagated with very little modification. In spite of the conserved nature of the matrix, dissorophid studies have produced anything but a conserved topology. Therefore, I analyzed an independently designed matrix, which recovered less resolution and some disparate nodes compared to previous studies. In order to reconcile these differences, I carefully examined previous matrices and analyses. While some differences are a matter of personal preference (e.g., analytical software), others relate to discrepancies with respect to what are currently considered as best practices. The most concerning discovery was the identification of pervasive dubious scorings that extend back to the origins of the widely propagated matrix. These include scores for skeletal features that are entirely unknown in a given taxon (e.g., postcrania in Cacops woehri) and characters for which there appear to be unstated working assumptions to scoring that are incompatible with the character definitions (e.g., scoring of taxa with incomplete skulls for characters based on skull length). Correction of these scores and other pervasive errors recovered a distinctly less resolved topology than previous studies, more in agreement with my own matrix. This suggests that previous analyses may have been compromised, and that the only real consensus of dissorophid phylogeny is the lack of one.
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Affiliation(s)
- Bryan M. Gee
- Burke Museum and Department of Biology, University of Washington, Seattle, WA, United States of America
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7
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Perez-Martinez CA, Leal M. Lizards as models to explore the ecological and neuroanatomical correlates of miniaturization. BEHAVIOUR 2021. [DOI: 10.1163/1568539x-bja10104] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Abstract
Extreme body size reductions bring about unorthodox anatomical arrangements and novel ways in which animals interact with the environment. Drawing from studies of vertebrates and invertebrates, we provide a theoretical framework for miniaturization to inform hypotheses using lizards as a study system. Through this approach, we demonstrate the repeated evolution of miniaturization across 11 families and a tendency for miniaturized species to occupy terrestrial microhabitats, possibly driven by physiological constraints. Differences in gross brain morphology between two gecko species demonstrate a proportionally larger telencephalon and smaller olfactory bulbs in the miniaturized species, though more data are needed to generalize this trend. Our study brings into light the potential contributions of miniaturized lizards to explain patterns of body size evolution and its impact on ecology and neuroanatomy. In addition, our findings reveal the need to study the natural history of miniaturized species, particularly in relation to their sensory and physiological ecology.
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Affiliation(s)
| | - Manuel Leal
- Division of Biological Sciences, University of Missouri, Columbia, MO 65201, USA
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8
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Strong CRC, Scherz MD, Caldwell MW. Deconstructing the Gestalt: New concepts and tests of homology, as exemplified by a re‐conceptualization of “microstomy” in squamates. Anat Rec (Hoboken) 2021; 304:2303-2351. [DOI: 10.1002/ar.24630] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 02/22/2021] [Accepted: 03/22/2021] [Indexed: 12/19/2022]
Affiliation(s)
| | - Mark D. Scherz
- Institute for Biochemistry and Biology University of Potsdam Potsdam Germany
| | - Michael W. Caldwell
- Department of Biological Sciences University of Alberta Edmonton Alberta Canada
- Department of Earth and Atmospheric Sciences University of Alberta Edmonton Alberta Canada
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9
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Strong CRC, Palci A, Caldwell MW. Insights into skull evolution in fossorial snakes, as revealed by the cranial morphology of Atractaspis irregularis (Serpentes: Colubroidea). J Anat 2021; 238:146-172. [PMID: 32815172 PMCID: PMC7755084 DOI: 10.1111/joa.13295] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/20/2020] [Accepted: 07/21/2020] [Indexed: 01/03/2023] Open
Abstract
Comparative osteological analyses of extant organisms provide key insight into major evolutionary transitions and phylogenetic hypotheses. This is especially true for snakes, given their unique morphology relative to other squamates and the persistent controversy regarding their evolutionary origins. However, the osteology of several major snake groups remains undescribed, thus hindering efforts to accurately reconstruct the phylogeny of snakes. One such group is the Atractaspididae, a family of fossorial colubroids. We herein present the first detailed description of the atractaspidid skull, based on fully segmented micro-computed tomography (micro-CT) scans of Atractaspis irregularis. The skull of Atractaspis presents a highly unique morphology influenced by both fossoriality and paedomorphosis. This paedomorphosis is especially evident in the jaws, palate, and suspensorium, the major elements associated with macrostomy (large-gaped feeding in snakes). Comparison to scolecophidians-a group of blind, fossorial, miniaturized snakes-in turn sheds light on current hypotheses of snake phylogeny. Features of both the naso-frontal joint and the morphofunctional system related to macrostomy refute the traditional notion that scolecophidians are fundamentally different from alethinophidians (all other extant snakes). Instead, these features support the controversial hypothesis of scolecophidians as "regressed alethinophidians," in contrast to their traditional placement as the earliest-diverging snake lineage. We propose that Atractaspis and scolecophidians fall along a morphological continuum, characterized by differing degrees of paedomorphosis. Altogether, a combination of heterochrony and miniaturization provides a mechanism for the derivation of the scolecophidian skull from an ancestral fossorial alethinophidian morphotype, exemplified by the nonminiaturized and less extreme paedomorph Atractaspis.
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Affiliation(s)
| | - Alessandro Palci
- Earth Sciences SectionSouth Australian MuseumAdelaideSAAustralia,College of Science and EngineeringFlinders UniversityBedford ParkSAAustralia
| | - Michael W. Caldwell
- Department of Biological SciencesUniversity of AlbertaEdmontonABCanada,Department of Earth and Atmospheric SciencesUniversity of AlbertaEdmontonABCanada
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10
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Brocklehurst N, Haridy Y. Do Meristic Characters Used in Phylogenetic Analysis Evolve in an Ordered Manner? Syst Biol 2020; 70:707-718. [PMID: 33104202 DOI: 10.1093/sysbio/syaa078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 09/27/2020] [Accepted: 10/02/2020] [Indexed: 11/13/2022] Open
Abstract
The use of ordered characters in phylogenetic analysis has been inconsistent throughout the history of phylogenetic inference. It has become more widespread in recent years, and some have advocated that all characters representing continuous or meristic traits should be ordered as a matter of course. Here, using the example of dental evolution, we examine two factors that may impact on whether meristic characters actually evolve in an ordered manner: the regulatory hierarchy governing the development of teeth that allows large sections of the entire tooth row to be suppressed in a single transition and regionalization of the tooth row where different modules have a degree of independence in their evolution. These are studied using both empirical and simulated data. Models of evolution of such characters are examined over molecular phylogenies to see if ordered or unordered models fit best. Simulations of tooth-row evolution are designed to incorporate changes in region size and multiple levels of developmental control to suppress individual regions or the entire row. The empirical analyses show that in a clade with largely homodont dentition the characters evolve in an ordered manner, but if dentition is heterodont with distinct regionalization their evolution better fits an unordered model. In the simulations, even if teeth are added and removed from the tooth row in an ordered manner, dividing the row into independently evolving modules can lead to characters covering multiple modules better fitting an unordered model of evolution. Adding the ability to suppress regions or the entire tooth row has a variable effect depending on the rates of suppression relative to the rates of addition and subtraction of individual teeth. We therefore advise not following a single policy when deciding whether to order meristic traits but to base the decision on a priori knowledge of the focal clade's evolution and developmental biology. [Discrete characters; ordered characters; phylogeny; teeth.].
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Affiliation(s)
- Neil Brocklehurst
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3QR, UK
| | - Yara Haridy
- Museum für Naturkunde Berlin, Invalidenstraße 43, 10115 Berlin, Germany
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11
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Pardo JD, Lennie K, Anderson JS. Can We Reliably Calibrate Deep Nodes in the Tetrapod Tree? Case Studies in Deep Tetrapod Divergences. Front Genet 2020; 11:506749. [PMID: 33193596 PMCID: PMC7596322 DOI: 10.3389/fgene.2020.506749] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 09/03/2020] [Indexed: 12/12/2022] Open
Abstract
Recent efforts have led to the development of extremely sophisticated methods for incorporating tree-wide data and accommodating uncertainty when estimating the temporal patterns of phylogenetic trees, but assignment of prior constraints on node age remains the most important factor. This depends largely on understanding substantive disagreements between specialists (paleontologists, geologists, and comparative anatomists), which are often opaque to phylogeneticists and molecular biologists who rely on these data as downstream users. This often leads to misunderstandings of how the uncertainty associated with node age minima arises, leading to inappropriate treatments of that uncertainty by phylogeneticists. In order to promote dialogue on this subject, we here review factors (phylogeny, preservational megabiases, spatial and temporal patterns in the tetrapod fossil record) that complicate assignment of prior node age constraints for deep divergences in the tetrapod tree, focusing on the origin of crown-group Amniota, crown-group Amphibia, and crown-group Tetrapoda. We find that node priors for amphibians and tetrapods show high phylogenetic lability and different phylogenetic treatments identifying disparate taxa as the earliest representatives of these crown groups. This corresponds partially to the well-known problem of lissamphibian origins but increasingly reflects deeper instabilities in early tetrapod phylogeny. Conversely, differences in phylogenetic treatment do not affect our ability to recognize the earliest crown-group amniotes but do affect how diverse we understand the earliest amniote faunas to be. Preservational megabiases and spatiotemporal heterogeneity of the early tetrapod fossil record present unrecognized challenges in reliably estimating the ages of tetrapod nodes; the tetrapod record throughout the relevant interval is spatially restricted and disrupted by several major intervals of minimal sampling coincident with the emergence of all three crown groups. Going forward, researchers attempting to calibrate the ages for these nodes, and other similar deep nodes in the metazoan fossil record, should consciously consider major phylogenetic uncertainty, preservational megabias, and spatiotemporal heterogeneity, preferably examining the impact of working hypotheses from multiple research groups. We emphasize a need for major tetrapod collection effort outside of classic European and North American sections, particularly from the southern hemisphere, and suggest that such sampling may dramatically change our timelines of tetrapod evolution.
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Affiliation(s)
- Jason D. Pardo
- Department of Comparative and Experimental Biology, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
- McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, AB, Canada
| | - Kendra Lennie
- McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, AB, Canada
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Jason S. Anderson
- Department of Comparative and Experimental Biology, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
- McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, AB, Canada
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12
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Gee BM. Size matters: the effects of ontogenetic disparity on the phylogeny of Trematopidae (Amphibia: Temnospondyli). Zool J Linn Soc 2020. [DOI: 10.1093/zoolinnean/zlz170] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Trematopids are a clade of terrestrial Permo-Carboniferous temnospondyl amphibians. The intrarelationships of this clade are poorly known. This is largely attributable to a substantial disparity in size between type specimens, which range from the small-bodied lectotype of Mattauschia laticeps (< 4 cm skull length) to the large-bodied holotype of Acheloma cumminsi (> 15 cm skull length). Inferred correlation of size disparity with ontogenetic disparity has led previous workers either to omit taxa in phylogenetic analyses or to forgo an analysis altogether. Here, I take a specimen-level approach and multiple subsampling permutations to explore the phylogeny of the Trematopidae as a case study for assessing the effects of ontogenetic disparity on phylogenetic reconstruction in temnospondyls. The various analyses provide evidence that ontogenetic disparity confounds the phylogenetic inference of trematopids but without a directional bias. Tree topologies of most permutations are poorly resolved and weakly supported, reflecting character conflict that results from the inability of the analyses to differentiate retained plesiomorphies from juvenile features. These findings urge caution in the interpretation of phylogenetic analyses for which ontogenetic disparity exists, but is unaccounted for, and provide a strong impetus for more directed exploration of the interplay of ontogeny and phylogeny across Temnospondyli.
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Affiliation(s)
- Bryan M Gee
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
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13
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Atkins JB, Reisz RR, Maddin HC. Braincase simplification and the origin of lissamphibians. PLoS One 2019; 14:e0213694. [PMID: 30901341 PMCID: PMC6430379 DOI: 10.1371/journal.pone.0213694] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 02/26/2019] [Indexed: 12/26/2022] Open
Abstract
Dissorophoidea, a group of temnospondyl tetrapods that first appear in the Late Carboniferous, is made up of two clades ⎼ Olsoniformes and Amphibamiformes (Branchiosauridae and Amphibamidae) ⎼ the latter of which is widely thought to have given rise to living amphibians (i.e., Lissamphibia). The lissamphibian braincase has a highly derived morphology with several secondarily lost elements; however, these losses have never been incorporated into phylogenetic analyses and thus the timing and nature of these evolutionary events remain unknown. Hindering research into this problem has been the lack of phylogenetic analyses of Dissorophoidea that includes both taxonomically dense sampling and specific characters to document changes in the braincase in the lineage leading to Lissamphibia. Here we build on a recent, broadly sampled dissorophoid phylogenetic analysis to visualize key events in the evolution of the lissamphibian braincase. Our ancestral character state reconstructions show a clear, step-wise trend towards reduction of braincase ossification leading to lissamphibians, including reduction of the sphenethmoid, loss of the basioccipital at the Amphibamiformes node, and further loss of both the basisphenoid and the hypoglossal nerve foramina at the Lissamphibia node. Our analysis confirms that the highly derived condition of the lissamphibian braincase is characterized by overall simplification in terms of the number and extent of chondrocranial ossifications.
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Affiliation(s)
- Jade B. Atkins
- Department of Earth Sciences, Carleton University, Ottawa, ON, Canada
- * E-mail:
| | - Robert R. Reisz
- Department of Biology, University of Toronto at Mississauga, Mississauga, ON, Canada
- International Center of Future Science, Dinosaur Evolution Research Center, Jilin University, Changchun, China
| | - Hillary C. Maddin
- Department of Earth Sciences, Carleton University, Ottawa, ON, Canada
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Gee BM, Bevitt JJ, Garbe U, Reisz RR. New material of the 'microsaur' Llistrofus from the cave deposits of Richards Spur, Oklahoma and the paleoecology of the Hapsidopareiidae. PeerJ 2019; 7:e6327. [PMID: 30701139 PMCID: PMC6348957 DOI: 10.7717/peerj.6327] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 12/17/2018] [Indexed: 12/20/2022] Open
Abstract
The Hapsidopareiidae is a group of “microsaurs” characterized by a substantial reduction of several elements in the cheek region that results in a prominent, enlarged temporal emargination. The clade comprises two markedly similar taxa from the early Permian of Oklahoma, Hapsidopareion lepton and Llistrofus pricei, which have been suggested to be synonymous by past workers. Llistrofus was previously known solely from the holotype found near Richards Spur, which consists of a dorsoventrally compressed skull in which the internal structures are difficult to characterize. Here, we present data from two new specimens of Llistrofus. This includes data collected through the use of neutron tomography, which revealed important new details of the palate and the neurocranium. Important questions within “Microsauria” related to the evolutionary transformations that likely occurred as part of the acquisition of the highly modified recumbirostran morphology for a fossorial ecology justify detailed reexamination of less well-studied taxa, such as Llistrofus. Although this study eliminates all but one of the previous features that differentiated Llistrofus and Hapsidopareion, the new data and redescription identify new features that justify the maintained separation of the two hapsidopareiids. Llistrofus possesses some of the adaptations for a fossorial lifestyle that have been identified in recumbirostrans but with a lesser degree of modification (e.g., reduced neurocranial ossification and mandibular modification). Incorporating the new data for Llistrofus into an existing phylogenetic matrix maintains the Hapsidopareiidae’s (Llistrofus + Hapsidopareion) position as the sister group to Recumbirostra. Given its phylogenetic position, we contextualize Llistrofus within the broader “microsaur” framework. Specifically, we propose that Llistrofus may have been fossorial but was probably incapable of active burrowing in the fashion of recumbirostrans, which had more consolidated and reinforced skulls. Llistrofus may represent an earlier stage in the step-wise acquisition of the derived recumbirostran morphology and paleoecology, furthering our understanding of the evolutionary history of “microsaurs.”
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Affiliation(s)
- Bryan M Gee
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Joseph J Bevitt
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia
| | - Ulf Garbe
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia
| | - Robert R Reisz
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada.,International Centre of Future Science, Jilin University, Changchun, Jilin Province, China
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Marjanović D, Laurin M. Phylogeny of Paleozoic limbed vertebrates reassessed through revision and expansion of the largest published relevant data matrix. PeerJ 2019; 6:e5565. [PMID: 30631641 PMCID: PMC6322490 DOI: 10.7717/peerj.5565] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 08/12/2018] [Indexed: 01/23/2023] Open
Abstract
The largest published phylogenetic analysis of early limbed vertebrates (Ruta M, Coates MI. 2007. Journal of Systematic Palaeontology 5:69-122) recovered, for example, Seymouriamorpha, Diadectomorpha and (in some trees) Caudata as paraphyletic and found the "temnospondyl hypothesis" on the origin of Lissamphibia (TH) to be more parsimonious than the "lepospondyl hypothesis" (LH)-though only, as we show, by one step. We report 4,200 misscored cells, over half of them due to typographic and similar accidental errors. Further, some characters were duplicated; some had only one described state; for one, most taxa were scored after presumed relatives. Even potentially continuous characters were unordered, the effects of ontogeny were not sufficiently taken into account, and data published after 2001 were mostly excluded. After these issues are improved-we document and justify all changes to the matrix-but no characters are added, we find (Analysis R1) much longer trees with, for example, monophyletic Caudata, Diadectomorpha and (in some trees) Seymouriamorpha; Ichthyostega either crownward or rootward of Acanthostega; and Anthracosauria either crownward or rootward of Temnospondyli. The LH is nine steps shorter than the TH (R2; constrained) and 12 steps shorter than the "polyphyly hypothesis" (PH-R3; constrained). Brachydectes (Lysorophia) is not found next to Lissamphibia; instead, a large clade that includes the adelogyrinids, urocordylid "nectrideans" and aïstopods occupies that position. As expected from the taxon/character ratio, most bootstrap values are low. Adding 56 terminal taxa to the original 102 increases the resolution (and decreases most bootstrap values). The added taxa range in completeness from complete articulated skeletons to an incomplete lower jaw. Even though the lissamphibian-like temnospondyls Gerobatrachus, Micropholis and Tungussogyrinus and the extremely peramorphic salamander Chelotriton are added, the difference between LH (R4; unconstrained) and TH (R5) rises to 10 steps, that between LH and PH (R6) to 15; the TH also requires several more regains of lost bones than the LH. Casineria, in which we tentatively identify a postbranchial lamina, emerges rather far from amniote origins in a gephyrostegid-chroniosuchian grade. Bayesian inference (Analysis EB, settings as in R4) mostly agrees with R4. High posterior probabilities are found for Lissamphibia (1.00) and the LH (0.92); however, many branches remain weakly supported, and most are short, as expected from the small character sample. We discuss phylogeny, approaches to coding, methods of phylogenetics (Bayesian inference vs. equally weighted vs. reweighted parsimony), some character complexes (e.g. preaxial/postaxial polarity in limb development), and prospects for further improvement of this matrix. Even in its revised state, the matrix cannot provide a robust assessment of the phylogeny of early limbed vertebrates. Sufficient improvement will be laborious-but not difficult.
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Affiliation(s)
- David Marjanović
- Science Programme “Evolution and Geoprocesses”, Museum für Naturkunde—Leibniz Institute for Evolutionary and Biodiversity Research, Berlin, Germany
| | - Michel Laurin
- Centre de Recherches sur la Paléobiologie et les Paléoenvironnements (CR2P), Centre national de la Recherche scientifique (CNRS)/Muséum national d’Histoire naturelle (MNHN)/Sorbonne Université, Paris, France
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16
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Simões TR, Vernygora O, Paparella I, Jimenez-Huidobro P, Caldwell MW. Mosasauroid phylogeny under multiple phylogenetic methods provides new insights on the evolution of aquatic adaptations in the group. PLoS One 2017; 12:e0176773. [PMID: 28467456 PMCID: PMC5415187 DOI: 10.1371/journal.pone.0176773] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 04/17/2017] [Indexed: 11/28/2022] Open
Abstract
Mosasauroids were a successful lineage of squamate reptiles (lizards and snakes) that radiated during the Late Cretaceous (95-66 million years ago). They can be considered one of the few lineages in the evolutionary history of tetrapods to have acquired a fully aquatic lifestyle, similarly to whales, ichthyosaurs and plesiosaurs. Despite a long history of research on this group, their phylogenetic relationships have only been tested so far using traditional (unweighted) maximum parsimony. However, hypotheses of mosasauroid relationships and the recently proposed multiple origins of aquatically adapted pelvic and pedal features in this group can be more thoroughly tested by methods that take into account variation in branch lengths and evolutionary rates. In this study, we present the first mosasauroid phylogenetic analysis performed under different analytical methods, including maximum likelihood, Bayesian inference, and implied weighting maximum parsimony. The results indicate a lack of congruence in the topological position of halisaurines and Dallasaurus. Additionally, the genus Prognathodon is paraphyletic under all hypotheses. Interestingly, a number of traditional mosasauroid clades become weakly supported, or unresolved, under Bayesian analyses. The reduced resolutions in some consensus trees create ambiguities concerning the evolution of fully aquatic pelvic/pedal conditions under many analyses. However, when enough resolution was obtained, reversals of the pelvic/pedal conditions were favoured by parsimony and likelihood ancestral state reconstructions instead of independent origins of aquatic features in mosasauroids. It is concluded that most of the observed discrepancies among the results can be associated with different analytical procedures, but also due to limited postcranial data on halisaurines, yaguarasaurines and Dallasaurus.
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Affiliation(s)
- Tiago R. Simões
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Oksana Vernygora
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Ilaria Paparella
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | | | - Michael W. Caldwell
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada
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Danto M, Witzmann F, Fröbisch NB. Vertebral Development in Paleozoic and Mesozoic Tetrapods Revealed by Paleohistological Data. PLoS One 2016; 11:e0152586. [PMID: 27074015 PMCID: PMC4830443 DOI: 10.1371/journal.pone.0152586] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 03/16/2016] [Indexed: 11/18/2022] Open
Abstract
Basal tetrapods display a wide spectrum of vertebral centrum morphologies that can be used to distinguish different tetrapod groups. The vertebral types range from multipartite centra in stem-tetrapods, temnospondyls, and seymouriamorphs up to monospondylous centra in lepospondyls and have been drawn upon for reconstructing major evolutionary trends in tetrapods that are now considered textbook knowledge. Two modes of vertebral formation have been postulated: the multipartite vertebrae formed first as cartilaginous elements with subsequent ossification. The monospondylous centrum, in contrast, was formed by direct ossification without a cartilaginous precursor. This study describes centrum morphogenesis in basal tetrapods for the first time, based on bone histology. Our results show that the intercentra of the investigated stem-tetrapods consist of a small band of periosteal bone and a dense network of endochondral bone. In stereospondyl temnospondyls, high amounts of calcified cartilage are preserved in the endochondral trabeculae. Notably, the periosteal region is thickened and highly vascularized in the plagiosaurid stereospondyls. Among “microsaur” lepospondyls, the thickened periosteal region is composed of compact bone and the notochordal canal is surrounded by large cell lacunae. In nectridean lepospondyls, the periosteal region has a spongy structure with large intertrabecular spaces, whereas the endochondral region has a highly cancellous structure. Our observations indicate that regardless of whether multipartite or monospondylous, the centra of basal tetrapods display first endochondral and subsequently periosteal ossification. A high interspecific variability is observed in growth rate, organization, and initiation of periosteal ossification. Moreover, vertebral development and structure reflect different lifestyles. The bottom-dwelling Plagiosauridae increase their skeletal mass by hyperplasy of the periosteal region. In nectrideans, the skeletal mass decreases, as the microstructure is spongy and lightly built. Additionally, we observed that vertebral structure is influenced by miniaturization in some groups. The phylogenetic information that can be drawn from vertebral development, however, is limited.
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Affiliation(s)
- Marylène Danto
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstraße 43, 10115 Berlin, Germany
- * E-mail:
| | - Florian Witzmann
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstraße 43, 10115 Berlin, Germany
- Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island, RI 02912, United States of America
| | - Nadia B. Fröbisch
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstraße 43, 10115 Berlin, Germany
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18
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Fröbisch NB, Bickelmann C, Witzmann F. Early evolution of limb regeneration in tetrapods: evidence from a 300-million-year-old amphibian. Proc Biol Sci 2015; 281:20141550. [PMID: 25253458 PMCID: PMC4211449 DOI: 10.1098/rspb.2014.1550] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Salamanders are the only tetrapods capable of fully regenerating their limbs throughout their entire lives. Much data on the underlying molecular mechanisms of limb regeneration have been gathered in recent years allowing for new comparative studies between salamanders and other tetrapods that lack this unique regenerative potential. By contrast, the evolution of animal regeneration just recently shifted back into focus, despite being highly relevant for research designs aiming to unravel the factors allowing for limb regeneration. We show that the 300-million-year-old temnospondyl amphibian Micromelerpeton, a distant relative of modern amphibians, was already capable of regenerating its limbs. A number of exceptionally well-preserved specimens from fossil deposits show a unique pattern and combination of abnormalities in their limbs that is distinctive of irregular regenerative activity in modern salamanders and does not occur as variants of normal limb development. This demonstrates that the capacity to regenerate limbs is not a derived feature of modern salamanders, but may be an ancient feature of non-amniote tetrapods and possibly even shared by all bony fish. The finding provides a new framework for understanding the evolution of regenerative capacity of paired appendages in vertebrates in the search for conserved versus derived molecular mechanisms of limb regeneration.
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Affiliation(s)
- Nadia B Fröbisch
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstrasse 43, 10115 Berlin, Germany
| | - Constanze Bickelmann
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstrasse 43, 10115 Berlin, Germany
| | - Florian Witzmann
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstrasse 43, 10115 Berlin, Germany
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19
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Harrison LB, Larsson HCE. Among-Character Rate Variation Distributions in Phylogenetic Analysis of Discrete Morphological Characters. Syst Biol 2014; 64:307-24. [DOI: 10.1093/sysbio/syu098] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Luke B. Harrison
- Redpath Museum, McGill University, 859 Sherbrooke Street West Montreal, Quebec, Canada H3A 0C4 and 2Redpath Museum, McGill University, 859 Sherbrooke ST W, Montreal, Quebec, Canada H3A 0C4
| | - Hans C. E. Larsson
- Redpath Museum, McGill University, 859 Sherbrooke Street West Montreal, Quebec, Canada H3A 0C4 and 2Redpath Museum, McGill University, 859 Sherbrooke ST W, Montreal, Quebec, Canada H3A 0C4
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20
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Angielczyk KD, Ruta M. The Roots of Amphibian Morphospace: A Geometric Morphometric Analysis of Paleozoic Temnospondyls. ACTA ACUST UNITED AC 2012. [DOI: 10.3158/2158-5520-5.1.40] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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21
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Avaria-Llautureo J, Hernández CE, Boric-Bargetto D, Canales-Aguirre CB, Morales-Pallero B, Rodríguez-Serrano E. Body size evolution in extant Oryzomyini rodents: Cope's rule or miniaturization? PLoS One 2012; 7:e34654. [PMID: 22509339 PMCID: PMC3318010 DOI: 10.1371/journal.pone.0034654] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Accepted: 03/08/2012] [Indexed: 11/26/2022] Open
Abstract
At the macroevolutionary level, one of the first and most important hypotheses that proposes an evolutionary tendency in the evolution of body sizes is “Cope's rule". This rule has considerable empirical support in the fossil record and predicts that the size of species within a lineage increases over evolutionary time. Nevertheless, there is also a large amount of evidence indicating the opposite pattern of miniaturization over evolutionary time. A recent analysis using a single phylogenetic tree approach and a Bayesian based model of evolution found no evidence for Cope's rule in extant mammal species. Here we utilize a likelihood-based phylogenetic method, to test the evolutionary trend in body size, which considers phylogenetic uncertainty, to discern between Cope's rule and miniaturization, using extant Oryzomyini rodents as a study model. We evaluated body size trends using two principal predictions: (a) phylogenetically related species are more similar in their body size, than expected by chance; (b) body size increased (Cope's rule)/decreased (miniaturization) over time. Consequently the distribution of forces and/or constraints that affect the tendency are homogenous and generate this directional process from a small/large sized ancestor. Results showed that body size in the Oryzomyini tribe evolved according to phylogenetic relationships, with a positive trend, from a small sized ancestor. Our results support that the high diversity and specialization currently observed in the Oryzomyini tribe is a consequence of the evolutionary trend of increased body size, following and supporting Cope's rule.
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Affiliation(s)
- Jorge Avaria-Llautureo
- Laboratorio de Ecología Molecular & Filoinformática, Departamento de Zoología, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile
| | - Cristián E. Hernández
- Laboratorio de Ecología Molecular & Filoinformática, Departamento de Zoología, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile
- * E-mail:
| | - Dusan Boric-Bargetto
- Laboratorio de Ecología Molecular & Filoinformática, Departamento de Zoología, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile
| | - Cristian B. Canales-Aguirre
- Laboratorio de Ecología Molecular & Filoinformática, Departamento de Zoología, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile
| | - Bryan Morales-Pallero
- Laboratorio de Ecología Molecular & Filoinformática, Departamento de Zoología, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile
| | - Enrique Rodríguez-Serrano
- Laboratorio de Ecología Molecular & Filoinformática, Departamento de Zoología, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile
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22
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Maddin HC. Deciphering morphological variation in the braincase of caecilian amphibians (Gymnophiona). J Morphol 2011; 272:850-71. [PMID: 21538474 DOI: 10.1002/jmor.10953] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 01/10/2011] [Accepted: 02/10/2011] [Indexed: 11/12/2022]
Abstract
High levels of morphological homoplasy have hindered progress in understanding morphological evolution within gymnophione lissamphibians. Stemming from the hypothesis that the braincase has the potential to yield phylogenetic information, the braincases of 27 species (23 genera) of gymnophione amphibians were examined using high-resolution micro-computed tomography and histologically prepared specimens. Morphology of the brain and its relationship to features of the braincase is described, and it is shown that eight different patterns exist in the distribution of foramina in the antotic region. The distribution of variants is congruent with molecule-based phylogeny. Additionally, all variants are shown to correspond directly to stages along developmental continua, suggesting that the evolutionary truncation of development in the antotic region at various stages has driven the evolution of morphology in this region. Attempts to correlate the observed morphology with proxies of putative heterochronic events (including those attributable to burrowing, life history, and size) fail to explain the distribution of morphology if each proxy is considered separately. Thus, it is concluded that either currently unrecognized causes of heterochrony or combinations thereof have influenced morphology in different lineages independently. These data identify clades whose morphology can now be reconsidered in light of previously unrecognized heterochronic events, thereby providing a foundation for future analyses of the evolution of morphology within Gymnophiona as a whole. Most significantly, these data confirm, for the first time in a lissamphibian group, that the braincase can preserve important phylogenetic information that is otherwise obscured in regions of the skull that experience strong influences from functional constraints.
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Affiliation(s)
- Hillary C Maddin
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
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Maddin HC, Olori JC, Anderson JS. A redescription of Carrolla craddocki (Lepospondyli: Brachystelechidae) based on high-resolution CT, and the impacts of miniaturization and fossoriality on morphology. J Morphol 2011; 272:722-43. [DOI: 10.1002/jmor.10946] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2010] [Revised: 11/26/2010] [Accepted: 12/05/2010] [Indexed: 11/07/2022]
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24
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Fröbisch NB, Shubin NH. Salamander limb development: integrating genes, morphology, and fossils. Dev Dyn 2011; 240:1087-99. [PMID: 21465623 DOI: 10.1002/dvdy.22629] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/21/2011] [Indexed: 11/11/2022] Open
Abstract
The development of the tetrapod limb during skeletogenesis follows a highly conservative pattern characterized by a general proximo-distal progression in the establishment of skeletal elements and a postaxial polarity in digit development. Salamanders represent the only exception to this pattern and display an early establishment of distal autopodial structures, specifically the basale commune, an amalgamation of distal carpal and tarsal 1 and 2, and a distinct preaxial polarity in digit development. This deviance from the conserved tetrapod pattern has resulted in a number of hypotheses to explain its developmental basis and evolutionary history. Here we summarize the current knowledge of salamander limb development under consideration of the fossil record to provide a deep time perspective of this evolutionary pathway and highlight what data will be needed in the future to gain a better understanding of salamander limb development specifically and tetrapod limb development and evolution more broadly.
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Affiliation(s)
- Nadia B Fröbisch
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois, USA.
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SKUTSCHAS PAVEL, MARTIN THOMAS. Cranial anatomy of the stem salamander Kokartus honorarius (Amphibia: Caudata) from the Middle Jurassic of Kyrgyzstan. Zool J Linn Soc 2011. [DOI: 10.1111/j.1096-3642.2010.00663.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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26
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Fröbisch NB, Olori JC, Schoch RR, Witzmann F. Amphibian development in the fossil record. Semin Cell Dev Biol 2009; 21:424-31. [PMID: 19913630 DOI: 10.1016/j.semcdb.2009.11.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2009] [Revised: 10/30/2009] [Accepted: 11/04/2009] [Indexed: 10/20/2022]
Abstract
Ontogenetic series of extinct taxa are extremely rare and when preserved often incomplete and difficult to interpret. However, the fossil record of amphibians includes a number of well-preserved ontogenetic sequences for temnospondyl and lepospondyl taxa, which have provided valuable information about the development of these extinct groups. Here we summarize the current knowledge on fossil ontogenies of amphibians, their potential and limitations for relationship assessments, and discuss the insights they have provided for our understanding of the anatomy, life history, and ecology of extinct amphibians.
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Affiliation(s)
- Nadia B Fröbisch
- Department of Organismal Biology & Anatomy, University of Chicago, 1027 E 57th Street, Culver 108, Chicago, IL 60637, USA.
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