| 1. |
- Coiro, Mario, et al.
(författare)
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Parallel evolution of angiosperm-like venation in Peltaspermales : a reinvestigation of Furcula
- 2024
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Ingår i: New Phytologist. - 0028-646X .- 1469-8137. ; 242:6, s. 2845-2856
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Tidskriftsartikel (refereegranskat)abstract
- Leaf venation is a pivotal trait in the success of vascular plants. Whereas gymnosperms have single or sparsely branched parallel veins, angiosperms developed a hierarchical structure of veins that form a complex reticulum. Its physiological consequences are considered to have enabled angiosperms to dominate terrestrial ecosystems in the Late Cretaceous and Cenozoic.Although a hierarchical-reticulate venation also occurs in some groups of extinct seed plants, it is unclear whether these are stem relatives of angiosperms or have evolved these traits in parallel. Here, we re-examine the morphology of the enigmatic foliage taxon Furcula, a potential early Mesozoic angiosperm relative, and argue that its hierarchical vein network represents convergent evolution (in the Late Triassic) with flowering plants (which developed in the Early Cretaceous) based on details of vein architecture and the absence of angiosperm-like stomata and guard cells.We suggest that its nearest relatives are Peltaspermales similar to Scytophyllum and Vittaephyllum, the latter being a genus that originated during the Late Triassic (Carnian) and shares a hierarchical vein system with Furcula.We further suggest that the evolution of hierarchical venation systems in the early Permian, the Late Triassic, and the Early Cretaceous represent ‘natural experiments’ that might help resolve the selective pressures enabling this trait to evolve.
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| 2. |
- Denk, Thomas, et al.
(författare)
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Cenozoic migration of a desert plant lineage across the North Atlantic
- 2023
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 238:6, s. 2668-2684
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Tidskriftsartikel (refereegranskat)abstract
- Previous paleobotanical work concluded that Paleogene elements of the sclerophyllous subhumid vegetation of western Eurasia and western North America were endemic to these disjunct regions, suggesting that the southern areas of the Holarctic flora were isolated at that time. Consequently, molecular studies invoked either parallel adaptation to dry climates from related ancestors, or long-distance dispersal in explaining disjunctions between the two regions, dismissing the contemporaneous migration of dry-adapted lineages via land bridges as unlikely.We report Vauquelinia (Rosaceae), currently endemic to western North America, in Cenozoic strata of western Eurasia. Revision of North American fossils previously assigned to Vauquelinia confirmed a single fossil-species of Vauquelinia and one of its close relative Kageneckia.We established taxonomic relationships of fossil-taxa using diagnostic character combinations shared with modern species and constructed a time-calibrated phylogeny.The fossil record suggests that Vauquelinia, currently endemic to arid and subdesert environments, originated under seasonally arid climates in the Eocene of western North America and subsequently crossed the Paleogene North Atlantic land bridge (NALB) to Europe. This pattern is replicated by other sclerophyllous, dry-adapted and warmth-loving plants, suggesting that several of these taxa potentially crossed the North Atlantic via the NALB during Eocene times.
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| 3. |
- Steinthorsdottir, Margret, et al.
(författare)
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Searching for a nearest living equivalent for Bennettitales : a promising extinct plant group for stomatal proxy reconstructions of Mesozoic pCO(2)
- 2021
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Ingår i: GFF. - London : Informa UK Limited. - 1103-5897 .- 2000-0863. ; 143:2-3, s. 190-201
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Tidskriftsartikel (refereegranskat)abstract
- To understand Earth ' s climate variability and improve predictions of future climate change, studying past climates is an important avenue to explore. A previously published record of pCO(2), across the Triassic-Jurassic boundary (TJB, similar to 201 Ma) of East Greenland, showed that Bennettitales (Anamozomites and Pterophyllum) responded in parallel to the empirically proven pCO(2)-responders Ginkgoales, reducing their stomatal densities by half across the TJB, indicating a transient doubling of pCO(2). The abundance of fossil Bennettitales in Mesozoic strata and natural history museum collections worldwide offers enormous potential for further stomatal proxy pCO(2) reconstructions, but a suitable nearest living equivalent (NLE) should ideally first be identified for this extinct plant group. Using specimens from herbarium collections, three species of cycads, historically considered the best NLE, were tested for pCO(2) response, as well as two species of tree ferns, grown in experimental growth chambers. None responded to changes in pCO(2), and were consequently rejected as NLEs. Finally, two species of ferns were selected from the literature, and produced very similar pCO(2) compared to Ginkgoales. However, these understory ferns are not appropriate NLEs for Bennettitales due to differences in habitat and a distant evolutionary relationship. Future work should test additional plant groups, in particular seed plants such as basal angiosperms and Gnetales, for suitability as NLE for Bennettitales in pCO(2) reconstructions, for example through biogeochemical fingerprinting using infrared microspectroscopy. Until an appropriate NLE is identified, Bennettitales pCO(2) can be reconstructed based on cross-calibration of stomatal densities with those of co-occurring pCO(2) responders, such as Ginkgoales.
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