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1. Redescription of three basal anomodonts: a phylogenetic reassessment of the holotype of Eodicynodon oelofseni (NMQR 2913)

   https://doi.org/10.3389/feart.2023.1220341  

   Duhamel, Alienor; Benoit, Julien; Wynd, Brenen; Wright, April Marie; Rubidge, Bruce (February 2024, Frontiers in Earth Science)

   The Dicynodontia (Therapsida: Anomodontia) is one of the most successful Permo-Triassic terrestrial tetrapod clades and the oldest specimens are recorded from the middle PermianEodicynodonAssemblage Zone of South Africa. Their fossil record is abundant and species-rich across Pangea. By contrast, the fossil record of the basal-most anomodonts, which includes non-dicynodont anomodonts and early forms of dicynodonts, is patchy and their morphology and phylogeny are deduced from relatively few specimens. Discovered in 1982 and described in 1990, the holotype ofEodicynodon oelofseni(NMQR 2913) is one of the better-preserved early anomodont specimens. However, it has been suggested thatE. oelofsenidoes not belong to the genusEodicynodon. Here, using CT-scanning and 3D modeling, the skull ofEodicynodon oelofseni,Patranomodon nyaphuliiandEodicynodon oosthuizeniare redescribed. In the framework of this study, the application of 3D scanning technology to describe anatomical structures which were previously inaccessible in these fossils has enabled detailed redescription of the cranial morphology of the basal anomodontsPatranomodon,Eodicynodon oelofseniandE. oosthuizeniand led to a greater understanding of their cranial morphology and phylogenetic relationships. Based on an anatomical comparison and phylogenetic analyses (Bayesian and cladistics) the phylogenetic relationships of basal anomodonts are reassessed and it is suggested that NMQR 2913 does not belong to the genusEodicynodonbut likely represents a separate genus basal to other dicynodonts. A new genus is erected for NMQR 2913. This presents one of the first applications of Bayesian Inference of phylogeny on Therapsida. 

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2. Ice shelf basal melt rates from a high-resolution DEM record for Pine Island Glacier, Antarctica

   https://doi.org/10.5194/tc-2018-209  

   Shean, David E.; Joughin, Ian R.; Dutrieux, Pierre; Smith, Benjamin E.; Berthier, Etienne (October 2018, The Cryosphere Discussions)

   Abstract. Ocean-induced basal melting is directly and indirectly responsible for much of the Amundsen Sea Embayment ice loss in recent decades, but the total magnitude and spatiotemporal evolution of this melt is poorly constrained. To address this problem, we generated a record of high-resolution Digital Elevation Models (DEMs) for Pine Island Glacier (PIG) using commercial sub-meter satellite stereo imagery and integrated additional 2002–2015 DEM/altimetry data. We implemented a Lagrangian elevation change (Dh/Dt) framework to estimate ice shelf basal melt rates at 32–256-m resolution. We describe this methodology and consider basal melt rates and elevation change over the PIG shelf and lower catchment from 2008–2015. We document the evolution of Eulerian elevation change (dh/dt) and upstream propagation of thinning signals following the end of rapid grounding line retreat around 2010. Mean full-shelf basal melt rates for the 2008–2015 period were ~82–93 Gt/yr, with ~ 200–250 m/yr basal melt rates within large channels near the grounding line, ~ 10–30 m/yr over the main shelf, and ~ 0–10 m/yr over the North and South shelves, with the notable exception of a small area with rates of ~ 50–100 m/yr near the grounding line of a fast-flowing tributary on the South shelf. The observed basal melt rates show excellent agreement with, and provide context for, in situ basal melt rate observations. We also document the relative melt rates for km-scale basal channels and keels at different locations on the shelf and consider implications for ocean circulation and heat content. These methods and results offer new indirect observations of ice-ocean interaction and constraints on the processes driving sub-shelf melting beneath vulnerable ice shelves in West Antarctica. 

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3. Ecological convergence in phytochemistry and flower–insect visitor interactions along an Andean elevation gradient

   https://doi.org/10.1002/ece3.10418  

   Carvajal Acosta, Alma Nalleli; Formenti, Ludovico; Godschalx, Adrienne; Katsanis, Angelos; Schapheer, Constanza; Mooney, Kailen; Villagra, Cristian; Rasmann, Sergio (August 2023, Ecology and Evolution)

   Abstract The diversity of specialized molecules produced by plants radiating along ecological gradients is thought to arise from plants' adaptations to local conditions. Therefore, closely related species growing in similar habitats should phylogenetically converge, or diverge, in response to similar climates, or similar interacting animal communities. We here asked whether closely related species in the genusHaplopappus(Asteraceae) growing within the same elevation bands in the Andes, converged to produce similar floral odors. To do so, we combine untargeted analysis of floral volatile organic compounds with insect olfactory bioassay in congenericHaplopappus(Asteraceae) species growing within the same elevation bands along the Andean elevational gradient. We then asked whether the outcome of biotic interactions (i.e., pollination vs. seed predation) would also converge across species within the same elevation. We found that flower odors grouped according to their elevational band and that the main floral visitor preferred floral heads from low‐elevation band species. Furthermore, the cost–benefit ratio of predated versus fertilized seeds was consistent within elevation bands, but increased with elevation, from 6:1 at low to 8:1 at high elevations. In the light of our findings, we propose that climate and insect community changes along elevation molded a common floral odor blend, best adapted for the local conditions. Moreover, we suggest that at low elevation where floral resources are abundant, the per capita cost of attracting seed predators is diluted, while at high elevation, sparse plants incur a higher herbivory cost per capita. Together, our results suggest that phytochemical convergence may be an important factor driving plant–insect interactions and their ecological outcomes along ecological gradients. 

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4. Basal Channel Evolution on the Getz Ice Shelf, West Antarctica

   https://doi.org/10.1029/2019JF005293  

   Chartrand, A. M.; Howat, I. M. (August 2020, Journal of Geophysical Research: Earth Surface)

   Abstract Ice shelves regulate the ice‐ocean boundary by buttressing the flux of grounded ice into the ocean and are vulnerable to basal melt, which can lead to ice‐shelf thinning and loss of buttressing. Localized, enhanced basal melt can form basal channels, which may impact ice‐shelf stability. Here we investigate the evolution of the Getz Ice Shelf Basal Channel (GISBC) in West Antarctica using a novel suite of geophysical data, including Reference Elevation Model of Antarctica (REMA) digital elevation models, ICESat‐1 and ‐2 altimetry, Operation IceBridge altimetry and radar, and InSAR‐derived ice flow velocities. We describe basal‐channel and ice‐shelf change in both Eulerian and Lagrangian frameworks and document changes in the channel's shape and its lateral motion and estimate basal melting. We find a high degree of spatial and temporal variability in GISBC evolution, with several locations of active basal incision. Incision occurs at rates of up to 22 m a⁻¹at the head of the channel, which is extending toward the grounding line at a rate of ~1 km a⁻¹. Freeboard heights over areas of rapid basal incision are out of hydrostatic equilibrium. The GISBC is also migrating to the northwest, perpendicular to the northeasterly ice flow direction, at an average rate of 70–80 m a⁻¹. The spatiotemporal variability of evolution of the GISBC motivates further characterization of basal channels and their impact on ice‐shelf stability, so that these effects may more readily be incorporated in ice‐ocean models predicting ice flow and sea‐level rise. 

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5. Unnecessary splitting of genus-level clades reduces taxonomic stability in amphibians

   https://doi.org/10.3897/vz.74.e114285  

   Mahony, Stephen; Kamei, Rachunliu G; Brown, Rafe M; Chan, Kin Onn (March 2024, Vertebrate Zoology)

   Abstract Although the differentiation of clades at the species level is usually based on a justifiable and testable conceptual framework, the demarcation of supraspecific boundaries is less objective and often subject to differences of opinion. The increased availability of large-scale phylogenies has in part promulgated a practice of what we consider excessively splitting clades at the “genus” level. Many of these new genus-level splits are predicated on untenable supporting evidence (e.g., weakly supported phylogenies and purportedly “diagnostic” but actually variable, non-exclusive, or otherwise problematic opposing character state differences) without careful consideration of the effects on downstream applications. As case studies, we critically evaluate several recent examples of splitting established monophyletic genera in four amphibian families that resulted in the creation/elevation of 20 genus-level names (Dicroglossidae:Phrynoglossus,Oreobatrachus,Frethiasplit fromOccidozyga; Microhylidae:Nanohylasplit fromMicrohyla; Ranidae:Abavorana,Amnirana,Chalcorana,Humerana,Hydrophylax,Indosylvirana,Papurana,Pulchrana,Sylviranasplit fromHylarana; Rhacophoridae:Tamixalus,Vampyrius,Leptomantis,Zhangixalussplit fromRhacophorus,Rohanixalussplit fromFeihyla,Orixalussplit fromGracixalus, andTarugasplit fromPolypedates), and also address the taxonomic status of the monotypic genusPteroranarelative toHylarana. We reassess the original claims of diagnosability and justifications for splitting and argue that in many cases, the generic splitting of clades is not only unnecessary but also destabilizes amphibian taxonomy, leading to a host of downstream issues that affect categories of the user community (stakeholders such as taxonomists, conservationists, evolutionary biologists, biogeographers, museum curators, educators, and the lay public). As an alternative, we advocate for the use of the subgenus rank in some cases, which can be implemented to establish informative partitions for future research without compromising on information content, while avoiding gratuitous (and often transient) large-scale binomial (genus-species couplet) rearrangements. We encourage taxonomists to consider the actual needs and interests of the larger non-taxonomic end-user community who fund the majority of taxonomic research, and who require a system that remains reasonably stable and is relatively intuitive, without the need for inaccessible laboratory equipment or advanced technical scientific knowledge to identify amphibian species to the genus level. 

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