Nadia B. Fröbisch

Bio: Nadia B. Fröbisch is an academic researcher from Museum für Naturkunde. The author has contributed to research in topics: Limb development & Dissorophoidea. The author has an hindex of 18, co-authored 33 publications receiving 973 citations. Previous affiliations of Nadia B. Fröbisch include University of Toronto & McGill University.

A stem batrachian from the Early Permian of Texas and the origin of frogs and salamanders

Abstract: The origin of the amphibians (frogs, salamanders and caecilians) is one of the most controversial questions in vertebrate evolution, because of the large morphological and temporal gaps between today's amphibians and the extinct fossil forms The discovery of an unusually complete Palaeozoic amphibian from the Early Permian of Texas has now helped to fill that gap The new fossil has the overall appearance of a temnospondyl — an archaic amphibian — but boasts many characteristic features seen in modern frogs, toads and salamanders A phylogenetic analysis splits the modern amphibia into two groups, separating at some time before 330 million years ago, with frogs, toads and salamanders related to temnospondyls, and caecilians more closely related to the lepospondyls, another group of archaic amphibians Anderson and colleagues describe a fossil amphibian from the Early Permian of Texas that has the chassis of a temnospondyl but with the addition of many features seen in modern frogs, toads and salamanders A phylogenetic analysis splits modern Amphibia into two groups, with frogs, toads and salamanders related to temnospondyls, and caecilians to leopspndyls The origin of extant amphibians (Lissamphibia: frogs, salamanders and caecilians) is one of the most controversial questions in vertebrate evolution, owing to large morphological and temporal gaps in the fossil record1,2,3 Current discussions focus on three competing hypotheses: a monophyletic origin within either Temnospondyli4,5,6,7 or Lepospondyli8,9,10, or a polyphyletic origin with frogs and salamanders arising among temnospondyls and caecilians among the lepospondyls11,12,13,14,15,16 Recent molecular analyses are also controversial, with estimations for the batrachian (frog–salamander) divergence significantly older than the palaeontological evidence supports17,18 Here we report the discovery of an amphibamid temnospondyl from the Early Permian of Texas that bridges the gap between other Palaeozoic amphibians and the earliest known salientians19,20 and caudatans21 from the Mesozoic The presence of a mosaic of salientian and caudatan characters in this small fossil makes it a key taxon close to the batrachian (frog and salamander) divergence Phylogenetic analysis suggests that the batrachian divergence occurred in the Middle Permian, rather than the late Carboniferous as recently estimated using molecular clocks18,22, but the divergence with caecilians corresponds to the deep split between temnospondyls and lepospondyls, which is congruent with the molecular estimates

Metamorphosis and neoteny: alternative pathways in an extinct amphibian clade

Abstract: The Branchiosauridae was a clade of small amphibians from the Permo-Carboniferous with an overall salamander-like appearance. The clade is distinguished by an extraordinary fossil record that comprises hundreds of well-preserved specimens, representing a wide range of ontogenetic stages. Branchiosaurids had external gills and weakly ossified skeletons, and due to this larval appearance their status as neotenic (perennibranchiate) forms has long been accepted. Despite their extensive fossil record large specimens with an adult morphology appeared to be lacking altogether, but recently two adult specimens were identified in a rich sample of Apateon gracilis collected in the 19th century from a locality near Dresden, Saxony. These specimens are unique among branchiosaurids in showing a high level of ossification, including bones that have never been reported in a branchiosaur. These highlight the successive formation of features believed to indicate terrestrial locomotion, as well as feeding on larger prey items. Moreover, these transformations occurred in a small time window (whereas the degree of size increase is used as a proxy of time) and the degree of concentration of developmental events in branchiosaurids is unique among tetrapods outside the lissamphibians. These specimens are compared with large adults of the neotenic branchiosaurid Apateon caducus from the Saar-Nahe Basin, which despite their larger body size lack the features found in the adult A. gracilis specimens. These specimens give new insight into patterns of metamorphosis (morphological transformation) in branchiosaurids that are believed to be correlated to a change of habitat, and clearly show that different life-history pathways comparable to those of modern salamanders were already established in this Paleozoic clade.

Limb ossification in the Paleozoic branchiosaurid Apateon (Temnospondyli) and the early evolution of preaxial dominance in tetrapod limb development.

Abstract: SUMMARY Despite the wide range of shapes and sizes that accompany a vast variety of functions, the development of tetrapod limbs follows a conservative pattern of de novo condensation, branching, and segmentation. Development of the zeugopodium and digital arch typically occurs in a posterior to anterior sequence, referred to as postaxial dominance, with a digital sequence of 4–3–5–2–1. The only exception to this pattern in all of living Tetrapoda can be found in salamanders, which display a preaxial dominance in limb development, a de novo condensation of a basale commune (distal carpal/tarsal 1+2) and a precoccial development of digits I and II. These divergent patterns have puzzled researchers for over a century leading to various explanatory hypotheses. Despite many advances in research on tetrapod limb development, the divergent evolution of these two pathways and its causes are still not understood. Based on an extensive ontogenetic series we investigated the pattern of limb development of the 300 Ma old branchiosaurid amphibian Apateon. This revealed a preaxial dominance in limb development that was previously believed to be unique and derived for modern salamanders. The Branchiosauridae are favored as close relatives of extant salamanders in most phylogenetic hypotheses of the highly controversial origins and relationships of extant amphibians. The findings provide new insights into the evolution of developmental pathways in tetrapod limb development, the relationships of modern amphibians with possible Paleozoic antecedents, and their initial timing of divergence.

Testing the Impact of Miniaturization on Phylogeny: Paleozoic Dissorophoid Amphibians

Abstract: Among the diverse clade of Paleozoic dissorophoid amphibians, the small, terrestrial amphibamids and the neotenic branchiosaurids have frequently been suggested as possible antecedents of either all or some of the modern amphibian clades. Classically, amphibamids and branchiosaurids have been considered to represent distinct, but closely related clades within dissorophoids, but despite their importance for the controversial lissamphibian origins, a comprehensive phylogenetic analysis of small dissorophoids has thus far not been attempted. On the basis of an integrated data set, the relationships of amphibamids and branchiosaurids were analyzed using parsimony and Bayesian approaches. Both groups represent miniaturized forms and it was tested whether similar developmental pathways, associated with miniaturization, lead to an artificial close relationship of branchiosaurids and amphibamids. Moreover, the fit of the resulting tree topologies to the distribution of fossil taxa in the stratigraphic rock record was assessed as an additional source of information. The results show that characters associated with a miniaturized morphology are not responsible for the close clustering of branchiosaurids and amphibamids. Instead, all analyses invariably demonstrate a monophyletic clade of branchiosaurids highly nested within derived amphibamids, indicating that branchiosaurids represent a group of secondarily neotenic amphibamid dissorophoids. This understanding of the phylogenetic relationships of small dissorophoid amphibians provides a new framework for the discussion of their evolutionary history and the evolution of characters shared by branchiosaurids and/or amphibamids with modern amphibian taxa.

Deep-time evolution of regeneration and preaxial polarity in tetrapod limb development

Abstract: Among extant tetrapods, salamanders are unique in showing a reversed preaxial polarity in patterning of the skeletal elements of the limbs, and in displaying the highest capacity for regeneration, including full limb and tail regeneration. These features are particularly striking as tetrapod limb development has otherwise been shown to be a highly conserved process. It remains elusive whether the capacity to regenerate limbs in salamanders is mechanistically and evolutionarily linked to the aberrant pattern of limb development; both are features classically regarded as unique to urodeles. New molecular data suggest that salamander-specific orphan genes play a central role in limb regeneration and may also be involved in the preaxial patterning during limb development. Here we show that preaxial polarity in limb development was present in various groups of temnospondyl amphibians of the Carboniferous and Permian periods, including the dissorophoids Apateon and Micromelerpeton, as well as the stereospondylomorph Sclerocephalus. Limb regeneration has also been reported in Micromelerpeton, demonstrating that both features were already present together in antecedents of modern salamanders 290 million years ago. Furthermore, data from lepospondyl 'microsaurs' on the amniote stem indicate that these taxa may have shown some capacity for limb regeneration and were capable of tail regeneration, including re-patterning of the caudal vertebral column that is otherwise only seen in salamander tail regeneration. The data from fossils suggest that salamander-like regeneration is an ancient feature of tetrapods that was subsequently lost at least once in the lineage leading to amniotes. Salamanders are the only modern tetrapods that retained regenerative capacities as well as preaxial polarity in limb development.

The Osteology of the Reptiles

Abstract: IN no domain of zoological science have the con tributions of American naturalists been more splendid than in that of vertebrate palaeontology, and in the list of pioneer workers in this domain an honoured place will always be accorded to Samuel Wendell Williston, who, born and nurtured in obscurity, had by the time of his death in 1918 won his way to recogni tion as the chief authority upon the extinct amphibians and reptiles. Apart from his specialist papers upon fossil vertebrates and upon modern dipterous flies, Williston was well known to the general zoologist for his excellent book on “Water Reptiles of the Past and Present,” published in 1914, and during the last year of his life he was busily engaged in the preparation of a second work of a general character on “The Reptiles of the World, Recent and Fossil.” The volume now under review comprises the main part of this general work, so far as it had been completed at the time of the author's death, put into shape and edited at the competent hands of Prof. W. K. Gregory. The Osteology of the Reptiles. By Prof. Samuel Wendell Williston. Arranged and edited by Prof. William King Gregory. Pp. xiii + 300. (Cambridge, Mass.: Harvard University Press; London: Oxford University Press, 1925.) 18s. 6d. net.

Divergence time estimation using fossils as terminal taxa and the origins of Lissamphibia.

Abstract: Were molecular data available for extinct taxa, questions regarding the origins of many groups could be settled in short order. As this is not the case, various strategies have been proposed to combine paleontological and neontological data sets. The use of fossil dates as node age calibrations for divergence time estimation from molecular phylogenies is commonplace. In addition, simulations suggest that the addition of morphological data from extinct taxa may improve phylogenetic estimation when combined with molecular data for extant species, and some studies have merged morphological and molecular data to estimate combined evidence phylogenies containing both extinct and extant taxa. However, few, if any, studies have attempted to estimate divergence times using phylogenies containing both fossil and living taxa sampled for both molecular and morphological data. Here, I infer both the phylogeny and the time of origin for Lissamphibia and a number of stem tetrapods using Bayesian methods based on a data set containing morphological data for extinct taxa, molecular data for extant taxa, and molecular and morphological data for a subset of extant taxa. The results suggest that Lissamphibia is monophyletic, nested within Lepospondyli, and originated in the late Carboniferous at the earliest. This research illustrates potential pitfalls for the use of fossils as post hoc age constraints on internal nodes and highlights the importance of explicit phylogenetic analysis of extinct taxa. These results suggest that the application of fossils as minima or maxima on molecular phylogenies should be supplemented or supplanted by combined evidence analyses whenever possible.

An outline of higher-level classification and survey of taxonomic richness

Abstract: For the kingdom Animalia, 1,552,319 species have been described in 40 phyla in a new evolutionary classification. Among these, the phylum Arthropoda alone represents 1,242,040 species, or about 80% of the total. The most successful group, the Insecta (1,020,007 species), accounts for about 66% of all animals. The most successful insect order, Coleoptera (387,100 species), represents about 38% of all species in 39 insect orders. Another major group in Arthropoda is the class Arachnida (112,201 species), which is dominated by the mites and ticks (Acari 54,617 species) and spiders (43,579 species). Other highly diverse arthropod groups include Crustacea (66,914 species), Trilobitomorpha (19,606 species) and Myriapoda (11,885 species). The phylum Mollusca (117,358 species) is more diverse than other successful invertebrate phyla Platyhelminthes (29,285 species), Nematoda (24,783 species), Echinodermata (20,509 species), Annelida (17,210 species) and Bryozoa (10,941 species). The phylum Craniata, including the vertebrates, represents 64,832 species (for Recent taxa, except for amphibians): among these 7,694 described species of amphibians, 31,958 species of “fish” and 5,750 species of mammals.

Animal biodiversity: An outline of higher-level classification and survey of taxonomic richness (Addenda 2013).

Abstract: The kingdom Animalia is here estimated to have a total of 1,659,420 described species (including 133,692 fossil species) in 40 phyla. Among these, the most successful phylum Arthropoda alone represents 1,302,809 species, or about 78.5% of the total. The second largest phylum, Mollusca (118,061 species), is <10% of Arthropoda in diversity, but it is still much more diverse than other successful invertebrate phyla Platyhelminthes (29,488 species), Nematoda (25,043 species), Echinodermata (20,550 species), Annelida (17,426 species), Cnidaria (16,363 species), Bryozoa (11,474 species) and Porifera (10,876 species). The phylum Craniata, including the vertebrates, represents 85,432 species (including 19,974 fossil species): among these, 35,644 species of "fishes", 7,171 species of amphibians, 15,507 species of reptiles, 11,087 species of birds, and 16,014 species of mammals.

Basic Structure and Evolution of Vertebrates.

Abstract: Structure and Evolution of Invertebrate Nervous SystemsDiscovering the BrainThe Structure and Evolution of the SunPolity and Governance: UPSC Prelims 2020 Highly Expected QuestionsThe Structure And Evolution Of StarsThe biology of Latimeria chalumnae and evolution of coelacanthsAn Introduction to the Theory of Stellar Structure and EvolutionSeismic and Numerical Constraints on the Formation and Evolution of Oceanic LithosphereStructure and Evolution of StarsDemocracy and Constitutionalism in IndiaThe Structure of Evolutionary TheoryEvolution of Magmatic and Diamond-Forming Systems of the Earth's Lower MantleComparative Structure and Evolution of Cerebral CortexValue, Competition and ExploitationRecords of the Western Australian MuseumThe Ocean BasinsThe Origin Nature and Evolution of Protoplasmic Individuals and Their AssociationsComparative Structure and Evolution of Cerebral CortexThe Structure and Evolution of StarsAn Introduction to the Evolution of Single and Binary StarsEvolution of the Vertebrate EarThe Evolution of the Primate HandBasic Structure and Evolution of VertebratesMajor Events in Early Vertebrate EvolutionEvolution and Development of FishesStellar InteriorsThe Structure and Evolution of GalaxiesThe Physics of StarsThe Evolution of the Primate HandCosmologyDetermination of Basic Structure-Property Relations for Processing and Modeling in Advanced Nuclear FuelThe Structure and Evolution of the SunPhysics, Formation and Evolution of Rotating StarsStructure and Evolution of Single StarsBuilding the Most Complex Structure on EarthDetermination of Basic Structure-property Relations for Processing and Modeling of Advanced Nuclear FuelsA Program of Ground-Based Astronomy to Complement Einstein ObservationsAn Introduction to the Theory of Stellar Structure and EvolutionRapport Grønlands Geologiske UndersøgelseComparative Genomics and Evolution of Eukaryotic Phospholipidbiosynthesis The Origin, Nature and Evolution of Protoplasmic Individuals and their Associations explores living beings of all levels of complexity in relation to each other and to the various ambient sources that they use to survive: protoplasmic individuals and their associations, cells and their associations, animals, and man. The book considers the concepts of evolution and of living beings; the main stages in biological evolution; the organisms' individuality, nature, way of formation, phylogenetic, and ontogenetic origin; essential property of the organisms of living beings; and creature modeling. The text also discusses the phylogenesis, ontogenesis, and the nature of the soma; the spatial and temporal environment connecting biological and geological evolution; and concepts of feeding and nutrition. Three separate sections describe phylogenetic origin of the first protoplasmic individuals; the protoplasmic individual as defined by its action and experience; and evolution in protoplasmic level.The Physics of Stars, Second Edition, is a concise introduction to the properties of stellar interiors and consequently the structure and evolution of stars. Strongly emphasising the basic physics, simple and uncomplicated theoretical models are used to illustrate clearly the connections between fundamental physics and stellar properties. This text does not intend to be encyclopaedic, rather it tends to focus on the most interesting and important aspects of stellar structure, evolution and nucleosynthesis. In the Second Edition, a new chapter on Helioseismology has been added, along with a list of physical constants and extra student problems. There is also new material on the HertztsprungRussell diagram, as well as a general updating of the entire text. It includes numerous problems at the end of each chapter aimed at both testing and extending student's knowledge.With the development of nuclear physics the theory of the stellar interior entered a new phase. Many new investigations have been conducted and the results published in a variety of specialized media. This book brings these results together in a single volume and summarizes the present status of the theory of stellar evolution. Originally published in 1958. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously outof-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.Phospholipid biosynthetic enzymes produce diverse molecular structures and are often present in multiple forms encoded by different genes. This work utilizes comparative genomics and phylogenetics for exploring the distribution, structure and evolution of phospholipid biosynthetic genes and pathways in 26 eukaryotic genomes. Although the basic structure of the pathways was formed early in eukaryotic evolution, the emerging picture indicates that individual enzyme families followed unique evolutionary courses. For example, choline and ethanolamine kinases and cytidylyltransferases emerged in ancestral eukaryotes, whereas, multiple forms of the corresponding phosphatidyltransferases evolved mainly in a lineage specific manner. Furthermore, several unicellular eukaryotes maintain bacterial-type enzymes and reactions for the synthesis of phosphatidylglycerol and cardiolipin. Also, base-exchange phosphatidylserine synthases are widespread and ancestral enzymes. The multiplicity of phospholipid biosynthetic enzymes has been largely generated by gene expansion in a lineage specific manner. Thus, these observations suggest that phospholipid biosynthesis has been an actively evolving system. Finally, comparative genomic analysis indicates the existence of novel phosphatidyltransferases and provides a candidate for the uncharacterized eukaryotic phosphatidylglycerol phosphate phosphatase.The objective of the funded research is to formulate and carry out a program of groundbased astronomical observations to complement X-ray data accumulated with the Einstein Observatory, and to use the results of these multiwavelength studies in addressing a number of significant astrophysical problems of current interest. The work focuses on three main topics: quasar emission mechanisms and their evolution; the structure and evolution of supernova remnants and the neutron stars which they may contain; and, the processes leading to high energy emission in the outer atmosphere (winds, coronae, etc) of main sequence stars. The physics to be addressed ranges from the generation and energetics of neutron star particle beams and their interaction with the surrounding medium to the details of supernova shock waves and their role in cosmic ray acceleration; from the basic structure of matter at supernuclear densities in neutron star interiors to the basic structure of the Universe as revealed in the evolution of quasars; and, from the study of the radiation processes in distant active galactic nuclei to the identification of the critical parameters which determine the level of coronal activity in nearby late-type stars. A detailed progress report is contained in section C below; sections D and F list the of the research reports and papers.This book equips the reader with a coherent understanding of the structure of the Sun and its evolution and provides all the knowledge required to construct a simplified model of the Sun. The early chapters cover key aspects of basic physics and describe the Sun’s size, mass, luminosity, and