ORCID Profile
0000-0003-4263-133X
Current Organisation
Baylor University
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Publisher: Elsevier BV
Date: 02-2016
Publisher: Wiley
Date: 02-2014
DOI: 10.3732/AJB.1300220
Abstract: Relationships of leaf size and shape (physiognomy) with climate have been well characterized for woody non-monocotyledonous angiosperms (dicots), allowing the development of models for estimating paleoclimate from fossil leaves. More recently, petiole width of seed plants has been shown to scale closely with leaf mass. By measuring petiole width and leaf area in fossils, leaf mass per area (MA) can be estimated and an approximate leaf life span inferred. However, little is known about these relationships in ferns, a clade with a deep fossil record and with the potential to greatly expand the applicability of these proxies. We measured the petiole width, MA, and leaf physiognomic characters of 179 fern species from 188 locations across six continents. We applied biomechanical models and assessed the relationship between leaf physiognomy and climate using correlational approaches. The scaling relationship between area-normalized petiole width and MA differs between fern fronds and pinnae. The scaling relationship is best modeled as an end-loaded cantilevered beam, which is different from the best-fit biomechanical model for seed plants. Fern leaf physiognomy is not influenced by climatic conditions. The cantilever beam model can be applied to fossil ferns. The lack of sensitivity of leaf physiognomy to climate in ferns argues against their use to reconstruct paleoclimate. Differences in climate sensitivity and biomechanical relationships between ferns and seed plants may be driven by differences in their hydraulic conductivity and/or their differing evolutionary histories of vein architecture and leaf morphology.
Publisher: Elsevier BV
Date: 08-2015
Publisher: American Association for the Advancement of Science (AAAS)
Date: 17-01-2020
Abstract: Around the time of the end-Cretaceous mass extinction that wiped out dinosaurs, there was both a bolide impact and a large amount of volcanism. Hull et al. ran several temperature simulations based on different volcanic outgassing scenarios and compared them with temperature records across the extinction event. The best model fits to the data required most outgassing to occur before the impact. When combined with other lines of evidence, these models support an impact-driven extinction. However, volcanic gases may have played a role in shaping the rise of different species after the extinction event. Science , this issue p. 266
Publisher: Center for Open Science
Date: 30-01-2020
Abstract: The Community of Open Scholarship Grassroots Networks (COSGN), includes 120 grassroots networks, representing virtually every region of the world and every research discipline. These networks communicate and coordinate on topics of common interest. We propose, using an NSF 19-501 Full-Scale implementation grant, to formalize governance and coordination of the networks to maximize impact and establish standard practices for sustainability. In the project period, we will increase the capacity of COSGN to advance the research and community goals of the participating networks in idually and collectively, and establish governance, succession planning, shared resources, andcommunication pathways to ensure an active, community-sustained network of networks. By the end of the project period, we will have established a self-sustaining network of networks that leverages disciplinary and regional ersity, actively collaborates across networks for grassroots organizing, and shares resources for maximum impact on culture change for open scholarship.
Publisher: Wiley
Date: 05-02-2011
DOI: 10.1111/J.1469-8137.2010.03615.X
Abstract: See also the Commentary by Burnham and Tonkovich
Publisher: Elsevier BV
Date: 02-2020
Publisher: Elsevier BV
Date: 02-2016
DOI: 10.1016/J.CUB.2015.12.050
Abstract: The fossil record provides tangible, historical evidence for the mode and operation of evolution across deep time. Striking patterns of convergence are some of the strongest ex les of these operations, whereby, over time, similar environmental and/or behavioral pressures precipitate similarity in form and function between disparately related taxa. Here we present fossil evidence for an unexpected convergence between gregarious plant-eating mammals and dinosaurs. Recent excavations of Late Pleistocene deposits on Rusinga Island, Kenya, have uncovered a catastrophic assemblage of the wildebeest-like bovid Rusingoryx atopocranion. Previously known from fragmentary material, these new specimens reveal large, hollow, osseous nasal crests: a craniofacial novelty for mammals that is remarkably comparable to the nasal crests of lambeosaurine hadrosaur dinosaurs. Using adult and juvenile material from this assemblage, as well as computed tomographic imaging, we investigate this convergence from morphological, developmental, functional, and paleoenvironmental perspectives. Our detailed analyses reveal broad parallels between R. atopocranion and basal Lambeosaurinae, suggesting that osseous nasal crests may require a highly specific combination of ontogeny, evolution, and environmental pressures in order to develop.
Publisher: Oxford University Press (OUP)
Date: 22-06-2021
DOI: 10.1093/AOB/MCAB078
Abstract: Leaf size has considerable ecological relevance, making it desirable to obtain leaf size estimations for as many species worldwide as possible. Current global databases, such as TRY, contain leaf size data for ~30 000 species, which is only ~8% of known species worldwide. Yet, taxonomic descriptions exist for the large majority of the remainder. Here we propose a simple method to exploit information on leaf length, width and shape from species descriptions to robustly estimate leaf areas, thus closing this considerable knowledge gap for this important plant functional trait. Using a global dataset of all major leaf shapes measured on 3125 leaves from 780 taxa, we quantified scaling functions that estimate leaf size as a product of leaf length, width and a leaf shape-specific correction factor. We validated our method by comparing leaf size estimates with those obtained from image recognition software and compared our approach with the widely used correction factor of 2/3. Correction factors ranged from 0.39 for highly dissected, lobed leaves to 0.79 for oblate leaves. Leaf size estimation using leaf shape-specific correction factors was more accurate and precise than estimates obtained from the correction factor of 2/3. Our method presents a tractable solution to accurately estimate leaf size when only information on leaf length, width and shape is available or when labour and time constraints prevent usage of image recognition software. We see promise in applying our method to data from species descriptions (including from fossils), databases, field work and on herbarium vouchers, especially when non-destructive in situ measurements are needed.
No related grants have been discovered for Daniel Peppe.