[dinosaur] Modern bird humerus disparity + frog skull evolution + Russian Permian tetrapod fauna redatinga +

Ben Creisler

Some recent non-dino papers:

Free pdf:

Francisco J. Serrano, Mireia Costa-PÃrez, Guillermo NavalÃn and Alberto MartÃn-Serra (2020)
Morphological Disparity of the Humerus in Modern Birds.
Diversity 12(5): 173
doi: https://doi.org/10.3390/d12050173
https://www.mdpi.com/1424-2818/12/5/173

From a functional standpoint, the humerus is a key element in the skeleton of vertebrates as it is the forelimbâs bone that connects with the pectoral girdle. In most birds, the humerus receives both the forces exerted by the main flight muscles and the aerodynamical stresses exerted upon the wing during locomotion. Despite this functional preeminence, broad scale studies of the morphological disparity of the humerus in the crown group of birds (Neornithes) are lacking. Here, we explore the variation in shape of the humeral outline in modern birds and its evolutionary relationship with size and the evolution of different functional regimes, including several flight strategies, wing propelled diving and complete loss of wing locomotory function. Our findings suggest that most neornithines evolved repeatedly towards a general humeral morphology linked with functional advantages related with more efficient flapping. Lineages evolving high-stress locomotion such as hyperaeriality (e.g., swifts), hovering (e.g., hummingbirds) and wing-propelled diving (e.g., penguins) greatly deviate from this general trend, each exploring different morphologies. Secondarily flightless birds deviate to a lesser degree from their parent clades in humeral morphology likely as a result of the release from constraints related with wing-based locomotion. Furthermore, these taxa show a different allometric trend that flighted birds. Our results reveal that the constraints of aerial and aquatic locomotion are main factors shaping the macroevolution of humeral morphology in modern birds.Â

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Free pdf:

C. Bardua, ÂAâC. Fabre, ÂM. Bon, ÂK. Das, ÂE.L. Stanley, ÂD.C. Blackburn & A. Goswami (2020)
Evolutionary integration of the frog cranium
Evolution (advance online publication)
doi: https://doi.org/10.1111/evo.13984
https://onlinelibrary.wiley.com/doi/10.1111/evo.13984

Free pdf:
https://onlinelibrary.wiley.com/doi/pdf/10.1111/evo.13984

Evolutionary integration (covariation) of traits has long fascinated biologists because of its potential to elucidate factors that have shaped morphological evolution. Studies of tetrapod crania have identified patterns of evolutionary integration that reflect functional or developmental interactions among traits, but no studies to date have sampled widely across the speciesârich lissamphibian order, Anura (frogs). Frogs exhibit a vast range of cranial morphologies, life history strategies and ecologies. Here, using highâdensity morphometrics we capture cranial morphology for 172 anuran species, sampling every extant family. We quantify the pattern of evolutionary modularity in the frog skull and compare patterns in taxa with different life history modes. Evolutionary changes across the anuran cranium are highly modular, with a wellâintegrated 'suspensorium' involved in feeding. This pattern is strikingly similar to that identified for caecilian and salamander crania, suggesting replication of patterns of evolutionary integration across Lissamphibia. Surprisingly, possession of a feeding larval stage has no notable influence on cranial integration across frogs. However, lateâossifying bones exhibit higher integration than earlyâossifying bones. Finally, anuran cranial modules show diverse morphological disparities, supporting the hypothesis that modular variation allows mosaic evolution of the cranium, but we find no consistent relationship between degree of withinâmodule integration and disparity.

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V.I. Davydov, M.P. Arefiev, V.K. Golubev, E.V. Karasev, M.A. Naumcheva, M.D. Schmitz, V.V. Silantiev & V.V. Zharinova (2020)
Radioisotopic and biostratigraphic constraints on the classical Middle-Upper Permian succession and tetrapod fauna of the Moscow syneclise, Russia.
Geology (advance online publication)
DOI: https://doi.org/10.1130/G47172.1
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G47172.1/584576/Radioisotopic-and-biostratigraphic-constraints-on

The East European Platform and the PreUrals are the regions where the Permian System was first established, but the provincialism of fossils and lack of radioisotopic age control have prevented the use there of the regional Permian subdivisions used outside of the region. We report the first U-Pb zircon chemical abrasion-isotope dilution-thermal ionization mass spectrometry (CA-ID-TIMS) age of 253.95 Â 0.06 Ma for a volcanic tuff from the terrestrial upper part of the lower Vyatkian Regional Stage in the Moscow syneclise (Russia). This age greatly improves the correlation of the East European Platform and the PreUrals with the international geologic time scale, and contributes to our understanding of sedimentation within the Permian-Triassic transition in the studied region. The new radioisotopic age integrated within the regional chronostratigraphic framework reveals the synchrony in extinction of faunas of the Dinocephalian superassemblage in the studied region with that in South Africa.

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