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Avian wing extension-flexion in gliding + Cretaceous-Paleogene pan-trionychian turtle shell histology + snake-like lizards + Cretaceous polar fishes from Alaska + more
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Ben Creisler
May 8, 2025, 2:25:03 PMMay 8
to DinosaurMa...@googlegroups.com
Ben Creisler
Some recent non-dino papers:
Jasmin C. M. Wong, Vaibhav Joshi, Rajeev K. Jaiman and Douglas L. Altshuler (2025)
Wing extension–flexion coupled aeroelastic effects improve avian gliding performance
Journal of the Royal Society Interface 22(226): 20240753
doi: https://doi.org/10.1098/rsif.2024.0753
https://royalsocietypublishing.org/doi/10.1098/rsif.2024.0753
During flight, birds instigate remarkably large changes in wing shape, commonly termed ‘wing morphing’. These changes in shape, particularly extension–flexion, have been well documented to influence the production of aerodynamic forces. However, it is unknown how wing stiffness changes as a result of the structural rearrangements needed for morphing. We address this gap in knowledge through mechanical testing of in situ flight feathers in anaesthetized pigeons and found that while the most distal portion of the feathered wing remained unaffected, proximal areas saw an increase in out-of-plane stiffness due to wing folding. Following this, we used computational fluid–structure interaction simulations to evaluate how this morphing-coupled change in stiffness might modulate local flow patterns to affect aerodynamic performance. We found that flexible wings perform better than entirely rigid wings as an increase in near-wall vorticity delayed flow separation. Furthermore, an increase in stiffness in a folded wing during high-speed flight prevented the reduction in lift seen in more flexible cases caused by aeroelastic flutter modes destructively interfering with shed leading-edge vortices. Collectively, these results reveal that mechanical changes coupled with wing morphing can provide a speed-dependent mechanism to enhance flight performance.
Wing extension–flexion coupled aeroelastic effects improve avian gliding performance
Journal of the Royal Society Interface 22(226): 20240753
doi: https://doi.org/10.1098/rsif.2024.0753
https://royalsocietypublishing.org/doi/10.1098/rsif.2024.0753
During flight, birds instigate remarkably large changes in wing shape, commonly termed ‘wing morphing’. These changes in shape, particularly extension–flexion, have been well documented to influence the production of aerodynamic forces. However, it is unknown how wing stiffness changes as a result of the structural rearrangements needed for morphing. We address this gap in knowledge through mechanical testing of in situ flight feathers in anaesthetized pigeons and found that while the most distal portion of the feathered wing remained unaffected, proximal areas saw an increase in out-of-plane stiffness due to wing folding. Following this, we used computational fluid–structure interaction simulations to evaluate how this morphing-coupled change in stiffness might modulate local flow patterns to affect aerodynamic performance. We found that flexible wings perform better than entirely rigid wings as an increase in near-wall vorticity delayed flow separation. Furthermore, an increase in stiffness in a folded wing during high-speed flight prevented the reduction in lift seen in more flexible cases caused by aeroelastic flutter modes destructively interfering with shed leading-edge vortices. Collectively, these results reveal that mechanical changes coupled with wing morphing can provide a speed-dependent mechanism to enhance flight performance.
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Nathan Ong, Eric Snively & Holly N. Woodward (2025)
Paleohistology of Cretaceous-Paleogene pan-trionychian turtle shells
Journal of Anatomy (advance online publication)
doi: https://doi.org/10.1111/joa.14272
https://onlinelibrary.wiley.com/doi/epdf/10.1111/joa.14272
At the end of the Cretaceous, a bolide impact wiped out ~75% of life on Earth, but turtles show minimal gross anatomical changes. Herein, we examine the shell histology from trionychid turtles 2 million years before and 8 million years after the extinction event. We collected over 25,000 semi-quantitative and quantitative measurements and statistically compared them against latitude, stratigraphic position, lithologic context, ontogeny, phylogeny, and K/Pg survivorship to better understand the various ways in which each respective variable influences histology. We find that trionychids from mudstones and higher in section were larger and older. Traits hypothesized to be biomechanically relevant, like the plywood-like structure and suture margins, showed minimal change across the boundary, but shells in northern Danian deposits do appear to be selected for biomechanical resistivity. Turtles like Helopanoplia and Gilmoremys had well-vascularized external cortices with deep ornamentation pits devoid of Sharpey's fibers, which likely enclosed a dense vascular capillary bed. These turtles also have more intact primary cortical tissues and smaller medullary regions, meaning that they remodeled their shell infrequently compared with other turtles. Because the shell is used as a calcium storage reservoir to combat metabolic and respiratory blood acidosis, we suggest that the vascular capillary bed nestled among ornamentation may have aided in cutaneous respiration, which in turn lessened reliance on shell remodeling. Helopanoplia and Gilmoremys are among the few trionychids to go extinct at the end of the Cretaceous, suggesting that this adaptation was maladaptive during and after the extinction, though we lack the chronological resolution required to infer intermediate selective mechanisms. Paleocene taxa generally show subtle ornamentation with uniform Sharpey's fiber distribution and abundant remodeling. Specimens from ~9500 years after the K/Pg extinction are only modestly more remodeled compared with later Paleogene specimens, suggesting that freshwater ecosystems had almost fully recovered by this interval.
Nathan Ong, Eric Snively & Holly N. Woodward (2025)
Paleohistology of Cretaceous-Paleogene pan-trionychian turtle shells
Journal of Anatomy (advance online publication)
doi: https://doi.org/10.1111/joa.14272
https://onlinelibrary.wiley.com/doi/epdf/10.1111/joa.14272
At the end of the Cretaceous, a bolide impact wiped out ~75% of life on Earth, but turtles show minimal gross anatomical changes. Herein, we examine the shell histology from trionychid turtles 2 million years before and 8 million years after the extinction event. We collected over 25,000 semi-quantitative and quantitative measurements and statistically compared them against latitude, stratigraphic position, lithologic context, ontogeny, phylogeny, and K/Pg survivorship to better understand the various ways in which each respective variable influences histology. We find that trionychids from mudstones and higher in section were larger and older. Traits hypothesized to be biomechanically relevant, like the plywood-like structure and suture margins, showed minimal change across the boundary, but shells in northern Danian deposits do appear to be selected for biomechanical resistivity. Turtles like Helopanoplia and Gilmoremys had well-vascularized external cortices with deep ornamentation pits devoid of Sharpey's fibers, which likely enclosed a dense vascular capillary bed. These turtles also have more intact primary cortical tissues and smaller medullary regions, meaning that they remodeled their shell infrequently compared with other turtles. Because the shell is used as a calcium storage reservoir to combat metabolic and respiratory blood acidosis, we suggest that the vascular capillary bed nestled among ornamentation may have aided in cutaneous respiration, which in turn lessened reliance on shell remodeling. Helopanoplia and Gilmoremys are among the few trionychids to go extinct at the end of the Cretaceous, suggesting that this adaptation was maladaptive during and after the extinction, though we lack the chronological resolution required to infer intermediate selective mechanisms. Paleocene taxa generally show subtle ornamentation with uniform Sharpey's fiber distribution and abundant remodeling. Specimens from ~9500 years after the K/Pg extinction are only modestly more remodeled compared with later Paleogene specimens, suggesting that freshwater ecosystems had almost fully recovered by this interval.
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Maxwell T Olson and Philip J Bergmann (2025)
Different drivers of diversification for body elongation and limb reduction in convergently snake-like lizards
Evolution, qpaf095
doi: https://doi.org/10.1093/evolut/qpaf095
https://academic.oup.com/evolut/advance-article-abstract/doi/10.1093/evolut/qpaf095/8126553
Convergence is the evolution of similar phenotypes often due to similar selective pressures or constraints limiting evolutionary options. Snake-like morphologies, characterized by elongated bodies and reduced limbs, have evolved repeatedly among vertebrates, including numerous times in squamate reptiles (lizards and snakes). It has been suggested that elongation facilitates locomotion through substrates while limb reduction typically occurs in clade-specific patterns, but this has not been tested. We compared the fit of a series of habitat-specific and clade-specific models for the evolution of digits, phalanges. and trunk vertebrae in lizards. We found that species inhabiting fossorial and cluttered habitats differed in numbers of vertebrae, digits, and phalanges from species in other habitats. A model with habitat-specific rates fit best for vertebral evolution, with sand swimmers, litter dwellers, and burrowers having higher rates of vertebral evolution than non-fossorial taxa. However, we found digits and phalanges evolved in a clade-specific manner, with higher rates of limb evolution in certain clades. This suggests that limb reduction in snake-like lizards is dictated by clade-specific constraints. In contrast, fossoriality appears to relax functional constraints on vertebral number, facilitating body form diversification. These results suggest that the relaxation of constraints may be an additional mechanism for convergent evolution.
Different drivers of diversification for body elongation and limb reduction in convergently snake-like lizards
Evolution, qpaf095
doi: https://doi.org/10.1093/evolut/qpaf095
https://academic.oup.com/evolut/advance-article-abstract/doi/10.1093/evolut/qpaf095/8126553
Convergence is the evolution of similar phenotypes often due to similar selective pressures or constraints limiting evolutionary options. Snake-like morphologies, characterized by elongated bodies and reduced limbs, have evolved repeatedly among vertebrates, including numerous times in squamate reptiles (lizards and snakes). It has been suggested that elongation facilitates locomotion through substrates while limb reduction typically occurs in clade-specific patterns, but this has not been tested. We compared the fit of a series of habitat-specific and clade-specific models for the evolution of digits, phalanges. and trunk vertebrae in lizards. We found that species inhabiting fossorial and cluttered habitats differed in numbers of vertebrae, digits, and phalanges from species in other habitats. A model with habitat-specific rates fit best for vertebral evolution, with sand swimmers, litter dwellers, and burrowers having higher rates of vertebral evolution than non-fossorial taxa. However, we found digits and phalanges evolved in a clade-specific manner, with higher rates of limb evolution in certain clades. This suggests that limb reduction in snake-like lizards is dictated by clade-specific constraints. In contrast, fossoriality appears to relax functional constraints on vertebral number, facilitating body form diversification. These results suggest that the relaxation of constraints may be an additional mechanism for convergent evolution.
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Free pdf:
Archaeosiilik gilmulli gen. et sp. nov.
Nunikuluk gracilis gen. et sp. nov.
Sivulliusalmo alaskensis gen. et sp. nov.
Donald B. Brinkman, J. Andrés López, Gregory M. Erickson, Jaelyn J. Eberle, Xochitl Muñoz, Lauren N. Wilson, Zackary R. Perry, Alison M. Murray, Lisa Van Loon, Neil R. Banerjee & Patrick S. Druckenmiller (2025)
Fishes from the Upper Cretaceous Prince Creek Formation, North Slope of Alaska, and their palaeobiogeographical significance
Papers in Palaeontology 11(3): e70014
doi: https://doi.org/10.1002/spp2.70014
https://onlinelibrary.wiley.com/doi/10.1002/spp2.70014
Free pdf:
https://onlinelibrary.wiley.com/doi/epdf/10.1002/spp2.70014
The Upper Cretaceous Prince Creek Formation (PCF) of northern Alaska offers a unique glimpse into northern high-latitude, non-marine vertebrate assemblages, providing critical data on polar ecosystems during the late Campanian (c. 73 Ma). This study presents a comprehensive taxonomic assessment of fish fossils from the PCF, including macrofossils and microfossils obtained through bulk sampling. The assemblage demonstrates lower species richness compared with penecontemporaneous formations in mid-latitude North America, with notable absences of typical taxa such as Myledaphus, lepisosteids, and amiids. Teleost fishes dominate the assemblage, comprising both endemic species and taxa shared with the Western Interior. New esocids (Archaeosiilik gilmulli gen. et sp. nov. and Nunikuluk gracilis gen. et sp. nov.), the earliest known salmonid (Sivulliusalmo alaskensis gen. et sp. nov.) and the earliest known cypriniform suggest that these fishes possessed unique polar adaptations. The presence of the elasmobranch Squatina, as well as sturgeon and paddlefish in this assemblage further emphasizes the distinctive composition of this high-latitude ecosystem. These findings suggest that the polar environment significantly influenced fish diversity and distribution, supporting the hypothesis that some taxa, such as esocids and salmonids, were already adapted to higher-latitude environments during the Late Cretaceous. Additionally, the study expands our understanding of the latitudinal biogeography of Laramidian vertebrates, providing additional support for the hypothesis that a distinct polar faunal province, named the Paanaqtat Province, was present. This research not only enriches the palaeontological record but also offers new insights into the evolutionary and ecological dynamics of polar ecosystems during the Late Cretaceous.
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Free pdf:
Martin Ebert & Martina Kölbl-Ebert (2025)
Jurassic fish choking on floating belemnites
Scientific Reports 15: 16095
doi: https://doi.org/10.1038/s41598-025-00163-7
https://www.nature.com/articles/s41598-025-00163-7
Tharsis, an extinct genus of ray-finned fish (Actinopterygii) in the Late Jurassic, has but tiny teeth and is considered a micro-carnivore/visual zooplanktivore. A recent review of collection material, however, uncovered several specimens of Tharsis from the Late Jurassic (ca. 152 Ma) Plattenkalk deposits of the Solnhofen Archipelago with belemnites wedged in mouth and gill apparatus. In all cases, the rostrum reexits through the gill apparatus, whereas the broad phragmocone of the belemnite is firmly lodged in the mouth opening. Apparently, these micro-carnivore fish were in the habit of sucking remnants of decaying soft tissue or overgrowth such as algae or bacterial growth from floating objects, but when a streamlined floating belemnite rostrum accidentally was sucked into the mouth, they were no longer able to get rid of these deadly objects.
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Free pdf:
Daniel Sol, Antón Prego, Laura Olivé, Meritxell Genovart, Daniel Oro & Antonio Hernández-Matías (2025)
Adaptations to marine environments and the evolution of slow-paced life histories in endotherms
Nature Communications 16: 4265
doi: https://doi.org/10.1038/s41467-025-59273-5
https://www.nature.com/articles/s41467-025-59273-5
All organisms face a certain risk of dying before reproducing, putting strong pressure on individuals to reproduce as early as possible. Despite this, some organisms delay maturity, defer reproduction, and age slowly. The evolution of such slow-paced life is classically attributed to allometric effects and reduced extrinsic mortality, but might also result from the invasion of challenging environments requiring adaptations that boost adult survival yet impose substantial energetic and developmental costs. Here, we reveal that the invasion of marine environments by endotherms may have triggered adaptive shifts towards slow life histories, particularly in pelagic lineages. Such life history convergences may have been facilitated by the slow-paced nature of their non-marine ancestors, and were associated with adaptations for enhanced energy acquisition and storage, enabling a long reproductive lifespan at the expense of extended development. Ancestral traits and lifestyle changes might thus have been important in shaping the evolution of slow life histories.
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Free pdf:
Lu Zheng , Rosalam Che Me & Rahmita Wirza O. K. Rahmat (2025)
Application of 3D digital technologies in paleontological reconstruction: a systematic literature review
Cogent Social Sciences 11(1): 2495188
doi: https://doi.org/10.1080/23311886.2025.2495188
https://www.tandfonline.com/doi/full/10.1080/23311886.2025.2495188
Free pdf:
https://www.tandfonline.com/doi/epdf/10.1080/23311886.2025.2495188
Paleontology, the study of ancient life through fossilized remains, has experienced a transformative shift with the advent of digital technologies. Traditional methods such as manual reconstruction, molding, and casting, though foundational, are often time-consuming and risk damaging valuable specimens. In response, the field has embraced “virtual paleontology,” which employs three-dimensional (3D) digital tools to reconstruct, visualize, and study fossils. This study presents a systematic literature review on the application of three-dimensional digital technologies in paleontological reconstruction. The methodology consists of four steps: formulating the research problem, conducting a literature search, selecting studies, and extracting the data. Initially, 1275 peer-reviewed articles were gathered from five databases (ScienceDirect, Scopus, Web of Science, Google Scholar, IEEE), and 48 articles published between 2013 and 2024 were selected. These articles specifically address the use of three-dimensional digital technologies in paleontological reconstruction and research, and despite promising developments, this review acknowledges the challenges and limitations associated with digital restoration. Technical challenges, including data acquisition and software complexity, are discussed. Looking toward the future, the review outlines potential advancements and innovations in digital reconstruction. The importance of collaborative efforts and interdisciplinary approaches has been emphasized as the field pushes the boundaries of digital restoration capabilities.
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