Stephan Lautenschlager

Heterostracans are pivotal in examining the evolution of feeding and the head in jawed vertebrates as the stem‐gnathostomes in which the oral apparatus is more commonly preserved. However, most analyses of their feeding, especially recent studies using modern 3D imaging methods, have focused on a specific subgroup, the Pteraspidiformes. Athenaegis chattertoni from the Wenlockian (Silurian) of Canada is the stratigraphically oldest heterostracan preserving an articulated feeding apparatus and is critical for reconstructing ancestral states in the lineage. Here, we use x‐ray and synchrotron microtomography to re‐examine the oral apparatus of Athenaegis , revealing a number of differences with the original reconstruction. Most importantly, the oral region of Athenaegis consists of numerous imbricated oral plates which functioned as a single integrated unit rather than a V‐shaped arrangement separated by a medial seam. We show that Athenaegis , contrary to the original description, does not possess a medial postoral plate. The oral region was not capable of opening substantially as shown by the interdigitation of the oral plates, a close articulation with the surrounding plates, and an absence of muscle or ligament attachment points. We conclude a microphagous suspension feeding function of the oral apparatus for Athenaegis consistent with previous hypotheses of suspension feeding in heterostracans.

The Devonian fish‐to‐tetrapod transition and the subsequent conquest of land involved multiple amphibious stem and early tetrapod lineages, yet how these animals reduced their dependence on aquatic environments remains uncertain. Feeding is central to this transition, as early tetrapods likely moved from predominantly aquatic suction feeding to jaw‐based prey prehension and processing. Although recent functional approaches—including morphometrics, functional morphology and computational modelling—offer new perspectives, their interpretive strength depends on realistic soft‐tissue inputs, particularly cranial musculature. Here, we reconstruct the principal cranio‐mandibular (skull) musculature of the Middle Triassic capitosaur temnospondyl Mastodonsaurus giganteus to provide an explicit anatomical foundation for future functional and modelling studies of stem and early tetrapods and to refine ecological interpretations for this species. We formulate alternative muscle hypotheses within an extant phylogenetic bracket (EPB) framework that explicitly reflects uncertainty in temnospondyl placement (temnospondyl versus lepospondyl origin of lissamphibians). We developed hypotheses from a literature review and digital dissections of contrast‐enhanced soft‐tissue μCT datasets from selected extant bracket taxa and outgroups and assessed them against osteological correlates in M. giganteus . Our reconstruction indicates a more differentiated adductor system than commonly assumed, with subdivision of the adductor mandibulae externus and internus complexes and an inferred intramandibular component consistent with a cartilaginous sesamoid (‘ cartilago transiliens ’) functioning as a force‐transmitting pulley. We further provide osteological evidence for previously unrecognised pterygoideus components, suggesting additional jaw‐closing capacity and a potential contribution to rapid gape formation. The ‘tongue’ in M. giganteus was likely comparatively weak and less flexibly movable, while as a stereospondyl, it possessed a comparatively strong neck and specialised anterior ribs. Collectively, these traits are consistent with a mainly crocodile‐like bite‐and‐hold prehension ecology and likely indicate kinetic‐inertial feeding. Our muscle reconstruction further suggests a more balanced jaw‐opening/closing system that may have enabled compensatory suction during gape formation.

Anseriformes (waterfowl) and Galliformes (landfowl) are among the world most recognisable groups of birds, together comprising the clade Galloanserae. Despite their close evolutionary relationship, the skulls of adult anseriforms and galliforms exhibit strikingly distinct morphologies, the developmental basis and evolutionary history of which is poorly understood. To illuminate the developmental and evolutionary underpinnings of cranial disparity between and within these major extant bird clades, we quantitatively investigated ontogenetic changes in cranial morphology across galloanseran phylogenetic diversity, focusing on the previously unexplored post-hatching interval during which adult morphology takes shape. Our results reveal the combined effects of multiple heterochronic shifts early in galloanseran evolutionary history including anseriform hypermorphosis, along with influential nonheterochronic changes leading to substantially more disparate ontogenetic trajectories, and greater cranial variability, in anseriforms than galliforms. Key galloanseran fossils help clarify the polarity of evolutionary shifts in cranial development through galloanseran phylogenetic history and demonstrate that extant galliform cranial morphology is more constrained and retains a more plesiomorphic morphology than that of anseriforms. Our work helps illuminate the developmental basis of the iconic differences in cranial form between waterfowl and landfowl and illustrates the importance of broad phylogenetic and ontogenetic sampling for clarifying patterns of post-hatching developmental divergence among major vertebrate clades.

Devonian ctenacanth chondrichthyans reached body sizes similar to modern great white sharks and therefore might have been apex predators of the Devonian seas. However, very little is known about the diet and feeding behaviours of these large ancestral sharks. To reconstruct their ecological properties, teeth of the large Famennian (Late Devonian) chondrichthyan Ctenacanthus concinnus from the Anti-Atlas, Morocco, were analysed. The teeth show strong tooth wear with deep horizontal as well as vertical scratches. Dental microwear texture analysis, a well-established method for the reconstruction of diet and commonly used in terrestrial vertebrates, was applied for the first time, to our knowledge, to Palaeozoic vertebrates in this study. Furthermore, finite element analysis was performed to test the biomechanical properties of the teeth. By combining both analyses, as well as palaeoenvironmental data and tooth morphology, we demonstrate that the results from only one method can be insufficient and misleading. Ctenacanthus concinnus most likely was an opportunistic feeder like many modern sharks. Direct evidence and the results of our analyses suggest that Ctenacanthus fed on ectocochleate cephalopods, other chondrichthyans and further vertebrates using a combination of head movements including lateral head shaking to cut large prey items.

This study introduces a participatory science-inspired approach to teaching and curriculum design, involving undergraduate students directly in active research. Using a case study on dinosaur eye size, integrated into a first-year undergraduate course in Geology and Palaeontology at a UK university, this study presents the advantages and disadvantages of this approach for both teachers and learners. As part of the study, 22 undergraduate students were involved in data collection, analysis, and the subsequent publication processes, emphasizing active student participation in research. A subsequent survey demonstrated high student engagement and perceived relevance of this participatory science-style teaching approach. Results indicate that students found the approach appealing, engaging, and beneficial for understanding scientific concepts and methods. The case study shows that a participatory science approach through a course-based research experience can enhance student engagement and learning by providing meaningful, hands-on research experiences. This approach allowed students to apply theoretical knowledge in a realistic context, fostering their understanding of evolutionary theory through active data collection and analysis. However, care should be taken concerning data accuracy and ethical aspects, such as exploitation of labour and the recognition of knowledge creators and participants. Despite these challenges, the benefits of integrating such approaches into higher education curricula can be substantial, offering a valuable model for teaching evolutionary theory and related topics.

Over the past few decades, citizen science has proven to be a valuable tool for research projects by involving the public in large-scale data collection. This collaboration between researchers and volunteers has been shown to be highly beneficial, allowing for efficient data collection in shorter time frames than possible for individual researchers. This study introduces a citizen science-inspired approach to teaching and curriculum design, involving undergraduate students directly in active research. Using a case study on dinosaur eye size, integrated into a first-year undergraduate course in Geology and Palaeontology at a UK university, the study presents the advantages of this approach for both teachers and learners. As part of the study, 22 undergraduate students were involved in data collection, analysis, and the subsequent publication processes, emphasizing active student participation in research. A subsequent survey demonstrated high student engagement and perceived relevance of the citizen science-style teaching approach. Results indicate that students found the approach appealing, engaging, and beneficial for understanding scientific concepts and methods. The case study shows that a citizen science approach to research-informed teaching can enhance student engagement and learning by providing meaningful, hands-on research experiences. This approach allows students to apply theoretical knowledge in a realistic context, fostering independence in quantitative research skills and collaborative learning. Despite potential challenges related to data accuracy and student motivation, the benefits of integrating such approaches into higher education curricula are substantial, offering a valuable model for teaching in Earth Sciences and beyond.

Elongated upper canine teeth, commonly known as saber‐teeth, have evolved three times within the sub‐order Feliformia. The species that wielded them flourished throughout the Cenozoic and have historically been separated into two morphological groups: the dirk‐tooths with longer, flatter canines, and the scimitar‐tooths with shorter, serrated teeth. However, quantitative morphological analysis has not been conducted on these teeth to determine the true amount of diversity within the group, and how the upper canine morphology of extant feliforms compared to their extinct relatives has also not been explored. Using Geometric Morphometric analysis, it is shown that saber‐tooth upper canine morphology is exceptionally diverse, with no extant clade having all its members occupy the same morphospace based on tooth length and curvature. Instead, a neutral basal morphospace is observed for all groups and diversification from this basal position is seen as species become more derived. A distinct and consistent scimitar tooth morphology is also not observed within the morphospace. When compared with extant taxa, several saber‐tooth species are seen to be morphologically similar to extant feliforms, several of which exhibit novel dietary strategies in comparison to the obligate carnivore felids. Biomechanical analyses of different actual and theoretical tooth shapes demonstrate that saber‐teeth upper canines further represent a functional compromise between sharpness, curvature, and length on the one hand, and robustness and material investment on the other.

Oviraptorosaurians were a theropod dinosaur group that reached high diversity in the Late Cretaceous. Within oviraptorosaurians, the later diverging oviraptorids evolved distinctive crania which were extensively pneumatised, short and tall, and had a robust toothless beak, interpreted as providing a powerful bite for their herbivorous to omnivorous diet. The present study explores the ability of oviraptorid crania to resist large mechanical stresses compared with other theropods and where this adaptation originated within oviraptorosaurians. Digital 3D cranial models were constructed for the earliest diverging oviraptorosaurian, Incisivosaurus gauthieri, and three oviraptorids, Citipati osmolskae, Conchoraptor gracilis, and Khaan mckennai. Finite element analyses indicate oviraptorosaurian crania were stronger than those of other herbivorous theropods (Erlikosaurus and Ornithomimus) and were more comparable to the large, carnivorous Allosaurus. The cranial biomechanics of Incisivosaurus align with oviraptorids, indicating an early establishment of distinctive strengthened cranial biomechanics in Oviraptorosauria, even before the highly modified oviraptorid cranial morphology. Bite modelling, using estimated muscle forces, suggests oviraptorid crania may have functioned closer to structural safety limits. Low mechanical stresses around the beaks of oviraptorids suggest a convergently evolved, functionally distinct rhamphotheca, serving as a cropping/feeding tool rather than for stress reduction, when compared with other herbivorous theropods.