Jaw musculature during the dawn of turtle evolution

Using a new approach to study muscle anatomy in vertebrates, the fully differentiated jaw musculature of 42 turtle species was studied and character mappings were performed. Soft tissue arrangements were correlated to the temporal openings (emarginations) of the skull and the trochlearis system of the jaw apparatus among turtle taxa. When compared to the cranial anatomy of stem Testudines, most characters detected as diagnostic of particular extant groups have to be considered as being evolved first within Testudines. Hence, jaw muscle anatomy of extant turtles is difficult to compare to that of other reptilian taxa. Moreover, the high number of apomorphic character changes speaks for a divergating turtle and saurian morphotype of jaw musculature, which could indicate either a position of turtles outside of Sauria or a highly derived, undetectable origin within that group. In general, a low direct correlation of most soft and hard tissue characters was detected. This finding could imply that both character complexes are more integrated to each other driven by functional morphology; i.e., the composition of muscle fibre types. That condition highlights the difficulty in using gross anatomy of jaw muscle characters to interpret temporal bone arrangements among amniotes in genera

Domestication and the comparative embryology of birds

Studies of domesticated animals have greatly contributed to our understanding of avian embryology. Foundational questions in developmental biology were motivated by Aristotle's observations of chicken embryos. By the 19th century, the chicken embryo was at the center stage of developmental biology, but how closely does this model species mirror the ample taxonomic diversity that characterizes the avian tree of life? Here, we provide a brief overview of the taxonomic breadth of comparative embryological studies in birds. We particularly focused on staging tables and papers that attempted to document the timing of developmental transformations. We show that most of the current knowledge of avian embryology is based on Galliformes (chicken and quail) and Anseriformes (duck and goose). Nonetheless, data are available for some ecologically diverse avian subclades, including Struthioniformes (e.g., ostrich, emu) and Sphenisciformes (penguins). Thus far, there has only been a handful of descriptive embryological studies in the most speciose subclade of Aves, that is, the songbirds (Passeriniformes). Furthermore, we found that temporal variances for developmental events are generally uniform across a consensus chronological sequence for birds. Based on the available data, developmental trajectories for chicken and other model species appear to be highly similar. We discuss future avenues of research in comparative avian embryology in light of the currently available wealth of data on domesticated species and beyond.info:eu-repo/semantics/publishedVersio

Vergleichende Morphologie der Kiefermuskulatur der Beloniformes (Teleostei, Atherinomorpha)

The taxon Beloniformes represents a heterogeneous group of teleost fishes including distinct forms as ricefishes (Adrianichthyidae), flying fishes (Exocoetidae), halfbeaks (Hemiramphidae), needlefishes (Belonidae), and sauries (Scomberesocidae) which show an extraordinary diversity of their jaw morphology. Beside the monophyly of Beloniformes, the relationships of its major taxa are disputed resulting in the proposal of several conflicting phylogenetic hypotheses. In order to investigate the contribution of cranial soft tissue elements to this debate the morphology of the jaw apparatus of five representatives of Beloniformes and four related species were comparatively analysed based on manual dissections, Azan-stained serial sections and 3d reconstructions. The 37 cranial soft tissue characters described in this study were mapped onto the alternative topologies and supported at best the monophyly of Beloniformes. Although Oryzias latipes shows numerous autapomorphic characters, Beloniformes are characterised by a derived reduction of the intramandibular portion of m. adductor mandibulae and the specific course of truncus maxillaris, which separates near the jaw joint. Within Beloniformes a sister group relationship of Adrianichthyidae to a clade consisting of ((Exocoetidae + Hemiramphidae) + (Belonidae + Scomberesocidae)) is supported by the reduction of the external section of m. adductor mandibulae and the shift of the m. levator arcus palatini origin to the sphenotic. These different observed characters could be correlated altogether to the reduced mobility between the elongated beak-like jaw bones evolved within this group

Contributions to the Evolution and Development of Land Vertebrates

"Contributions to the Evolution and Development of Land Vertebrates" is the cumulative habilitation thesis of Ingmar Werneburg. In total, it contains 30 published articles and book chapters. Those publications are not part of the pdf due to copyright issues and are available elsewhere; however, a comprehensive summary of all studies is provided. The thesis is built of four major parts: A) Methodology, B) Developmental timing in an evolutionary framework, C) The craniocervical system in turtles, and D) Feeding in land vertebrates

Timing of organogenesis support basal position of turtles in the amniote tree of life

Background: The phylogenetic position of turtles is the most disputed aspect in the reconstruction of the land vertebrate tree of life. This controversy has arisen after many different kinds and revisions of investigations of molecular and morphological data. Three main hypotheses of living sister-groups of turtles have resulted from them: all reptiles, crocodiles + birds or squamates + tuatara. Although embryology has played a major role in morphological studies of vertebrate phylogeny, data on developmental timing have never been examined to explore and test the alternative phylogenetic hypotheses. We conducted a comprehensive study of published and new embryological data comprising 15 turtle and eight tetrapod species belonging to other taxa, integrating for the first time data on the side-necked turtle clade. Results: The timing of events in organogenesis of diverse character complexes in all body regions is not uniform across amniotes and can be analysed using a parsimony-based method. Changes in the relative timing of particular events diagnose many clades of amniotes and include a phylogenetic signal. A basal position of turtles to the living saurian clades is clearly supported by timing of organogenesis data. Conclusion: The clear signal of a basal position of turtles provided by heterochronic data implies significant convergence in either molecular, adult morphological or developmental timing characters, as only one of the alternative solutions to the phylogenetic conundrum can be right. The development of a standard reference series of embryological events in amniotes as presented here should enable future improvements and expansion of sampling and thus the examination of other hypotheses about phylogeny and patterns of the evolution of land vertebrate development

Palate anatomy and morphofunctional aspects of interpterygoid vacuities in temnospondyl cranial evolution

Temnospondyls were the morphologically and taxonomically most diverse group of early tetrapods with a near-global distribution during the Palaeozoic and Mesozoic. Members of this group occupied a range of different habitats (aquatic, amphibious, terrestrial), reflected by large morphological disparity of the cranium throughout their evolutionary history. A diagnostic feature of temnospondyls is the presence of an open palate with large interpterygoid vacuities, in contrast to the closed palate of most other early tetrapods and their fish-like relatives. Although the function of the interpterygoid vacuities has been discussed in the past, no quantitative studies have been performed to assess their biomechanical significance. Here, we applied finite element analysis, to test the possibility that the interpterygoid vacuities served for stress distribution during contraction of the jaw closing musculature. Different original and theoretical skull models, in which the vacuities differed in size or were completely absent, were compared for their mechanical performance. Our results demonstrate that palatal morphology played a considerable role in cranial biomechanics of temnospondyls. The presence of large cranial vacuities were found to offer the dual benefit of providing additional muscle attachment areas and allowing for more effective force transmission and thus an increase in bite force without compromising cranial stability

3D model related to the publication: The endocranial anatomy of the stem turtle Naomichelys speciosa from the Early Cretaceous of North America

The present 3D Dataset contains the 3D model analyzed in the following publication: Paulina-Carabajal, A., Sterli, J., Werneburg, I., 2019. The endocranial anatomy of the stem turtle Naomichelys speciosa from the Early Cretaceous of North America. Acta Palaeontologica Polonica, https://doi.org/10.4202/app.00606.2019.Fil: Paulina Carabajal, Ariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Sterli, Juliana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Museo Paleontológico Egidio Feruglio; ArgentinaFil: Werneburg, Ingmar. Eberhard Karls Universität Tübingen; Alemani

60. Phylogenetisches Symposium Tübingen: Funktionsmorphologie und Bionik

Tagungsprogramm, Abstracts der Vorträge und Postertitel nebst einer Einführung in die Geschichte der funktionsmorphologischen und bionischen Forschung in der Paläontologie und Biologie in Tübinge

Discovery of rare lecture notes from 1866 provides exceptional insights into the conceptualization and visualization of paleontology by Ernst Haeckel

Here we report on a recently discovered student script of a lecture on paleontology given by Ernst Haeckel (1834–1919). The script dates to the summer semester of 1866, comprises 63 pages, and provides an overview of fossil invertebrate and mainly fossil vertebrate taxonomy and anatomy. It can be assumed that Russian student Nikolai Nikolajevitch Miklucho-Maclay (1846–1888), who later became a famous ethnologist, did not follow up on the lecture, but took the content directly from the lecture and from the blackboard in his notes. Hence, the drawings by Miklucho allow direct insight into Haeckel’s visualization of paleontology in the 1860s. We place the transcript in the historical context of understanding paleontology in the second half of the 19th century and address the break between zoology and embryology on the one hand and paleontology on the other, which is typical for Germany, partly persisting to this date. For that, we illustrate Haeckel’s integration of paleontology as part of a holistic triad, with fossil research gradually taking a back seat to zoology and embryology over the decades