| 1. |
- Friis, Else Marie, et al.
(författare)
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Catanthus, an Extinct Magnoliid Flower from the Early Cretaceous of Portugal
- 2021
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Ingår i: International journal of plant sciences. - : University of Chicago Press. - 1058-5893 .- 1537-5315. ; 182, s. 28-45
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Tidskriftsartikel (refereegranskat)abstract
- Premise of research. Early Cretaceous flowers recovered from Portugal and North America are some of the oldest and most informative angiosperm structures known. Analyses of this material provide a more direct basis for inferring floral structure and biology in early angiosperms than extrapolations based solely on extant taxa, and they have documented an unanticipated diversity of angiosperms, including the presence of many extinct forms, during the Early Cretaceous. The fossil flower described here from the Early Cretaceous of Portugal adds to the knowledge of this extinct diversity.Methodology. Coalified fossil flowers were extracted from unconsolidated sediments and cleaned with HF, HCl, and water. Details were studied using scanning electron microscopy and synchrotron radiation X-ray tomographic microscopy. Phylogenetic relationships were evaluated by adding the fossil to a phylogenetic analysis of extant basal angiosperms based on morphological characters but constrained according to a topology based on molecular data.Pivotal results. A new genus and species, Catanthus dolichostemon, are described on the basis of the fossil flowers. The perianth consists of three thick sepal-like tepals in an outer whorl and six thinner petallike tepals in two inner whorls. The androecium consists of several whorls of stamens with long, broad filaments and anthers with extrorse dehiscence. Pollen is trichotomocolpate and possibly monocolpate. The gynoecium is superior and apocarpous, consisting of six or, rarely, five carpels. Analysis of the phylogenetic position of Catanthus suggests a relationship to Canellales and Magnoliales.Conclusions. Catanthus is a new Early Cretaceous magnoliid angiosperm for which the relationship to the two major clades of extant magnoliids (Laurales + Magnoliales or Canellales + Piperales) is not resolved securely. Catanthus adds to the evidence of substantial extinct diversity among early angiosperms, including the presence of extinct forms related to extant magnoliids, and it is consistent with a general pattern that angiosperm assemblages from the middle Albian and earlier are dominated by noneudicots.
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| 2. |
- Friis, Else Marie, et al.
(författare)
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Early and Mid-Cretaceous Aristolochiaceous Seeds from Portugal and Eastern North America
- 2022
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Ingår i: International journal of plant sciences. - Chicago : University of Chicago Press. - 1058-5893 .- 1537-5315. ; 183:7, s. 587-603
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Tidskriftsartikel (refereegranskat)abstract
- Premise of research. The fossil record of Aristolochiaceae (Piperales, magnoliids) is sparse, particularly from Cretaceous strata. Fossil seeds from the Early and mid-Cretaceous of Portugal and North America provide the earliest unequivocal documentation of the group.Methodology. Detailed morphological and anatomical investigations of the fossil aristolochiaceous seeds were carried out using SEM and synchrotron radiation X-ray tomographic microscopy (SRXTM). Comparison with other seeds, extinct as well as extant, was based on published data and SRXTM analyses.Pivotal results. Two new genera and two new species, Aristospermum huberi and Siratospermum mauldinense, are described based on fossil seeds from the Early and mid-Cretaceous of Portugal and North America. The seeds are anatropous and bitegmic, with the micropyle formed by the inner integument. The testa consists of an exotesta of varied thickness and an endotesta of crystalliferous cells. The tegmen is three cell layers thick and consists of an outermost layer of longitudinally aligned fibers, a middle layer of transversely aligned fibers perpendicular to the longitudinal fibers, and an inner layer of thin-walled cuboidal cells. In most seeds the exotesta is abraded, exposing the crystalliferous cells of the endotesta. Among extant plants, a similar seed coat with a crystalliferous endotesta and crossing fibers in the tegmen is unique to Aristolochiaceae.Conclusion. The unique seed coat allows Aristospermum and Siratospermum to be assigned confidently to the lineage that today includes extant Aristolochiaceae. Aristospermum and Siratospermum provide the first unequivocal documentation of the Aristolochiaceae lineage of the Piperales during the Early Cretaceous diversification of angiosperms.
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| 3. |
- Friis, Else Marie, et al.
(författare)
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Early flowers of primuloid Ericales from the Late Cretaceous of Portugal and their ecological and phytogeographic implications
- 2021
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Ingår i: Fossil Imprint. - Prague : Národní muzeum. - 2533-4050 .- 2533-4069. ; 77:2, s. 214-230
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Tidskriftsartikel (refereegranskat)abstract
- A distinctive feature of the major eudicot diversification that occurred through the Late Cretaceous is the unequivocal presence of Cornales and diverse Ericales. Here we describe well-preserved fossil flowers from the Mira locality in western Portugal, of Campanian-Maastrichtian age, that we assign to a new extinct genus of Ericales with two new species; Miranthus elegans gen. et sp. nov. and Miranthus kvacekii sp. nov. The fossil flowers are pedicellate, structurally bisexual, actinomorphic, pentamerous and isomerous, with five narrowly triangular persistent calyx lobes, a five-lobed corolla, five antepetalous stamens, five staminodes alternating with the petals and a semi-inferior, unilocular ovary. The ovary consists of five carpels and has a raised nectariferous ring with stomata-like openings above the insertion of the perianth, and a long five-angled style. A key feature, which confirms a relationship with Primulaceae s. l., is the free, central dome-shaped placenta that bears numerous, densely spaced ovules. The ovary matures into a capsule containing many, minute, reticulate seeds. Flowers of Miranthus are especially similar to those of extant Samolus, a genus of about twelve species that is sister group to other genera of subfamily Theophrastoideae and that has a disjunct distribution mainly in the Southern Hemisphere. Miranthus also appears to have grown in environments influenced by marine conditions, an ecological preference also seen in Samolus. Miranthus expands the diversity of Ericales known from the Late Cretaceous, and together with previously described fossils provides further evidence that the diversification of Ericales was already underway by the Campanian-Maastrichtian stages of the Late Cretaceous.
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| 4. |
- Friis, Else Marie, et al.
(författare)
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Extinct seed plant diversity in the Early Cretaceous: An enigmatic new microsporangiate fossil with Decussosporites pollen in situ
- 2022
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Ingår i: Review of Palaeobotany and Palynology. - Amsterdam : Elsevier. - 0034-6667 .- 1879-0615. ; 304, s. 104716-104716
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Tidskriftsartikel (refereegranskat)abstract
- A new microsporangiate cone, Renbernia zhoui, is described from the mesofossil flora extracted from exposures ofthe Potomac Group at Puddledock, Virginia, U.S.A., which are of Early Cretaceous (early-middle Albian) age. The cone consists of densely arranged dorsiventrally flattened laminar, flabelliform microsporangiophores that bear two elongate microsporangia on the presumed abaxial surface. The microsporangia are separated by sterile tissue that expands apically into a prominent hood-like sterile extension. The microsporangia have extrorse valvate dehiscence and both microsporangia and sterile apical expansion are covered by a short stiff hairs. In situ pollen resembles Decussosporites, elliptical with a long median colpus on the presumed distal surface flanked laterally by two equally long lateral colpi. A short transverse colpus on the presumed proximal surface links the two lateral colpi and divides the grain into two parts creating the appearance of two sacci. Renbernia zhoui is similar to Brenneria potomacensis described from the slightly older Drewry's Bluff and Dutch Gap mesofossil floras from the Potomac Group that also has Decussosporites-type pollen in situ. However, Renbernia microsporangiophores are more distinctly laminar and have sporangia that are more prominently elongated and with a hood-like apical extension of sterile tissue. The in situ pollen is also much smaller, the pollen wall is much more distinctly perforate-foveolate rather than more or less psilate, and in Renbernia the saccus-like structures are not inflated. The relationship of Brenneria and Renbernia, as well as the possible link between Decussosporites-type pollen and pollen of Eucommiidites (Erdtmanithecales) is discussed.
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| 5. |
- Friis, Else Marie, et al.
(författare)
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Melloniflora, a new extinct multiparted flower from the Early Cretaceous of Virginia
- 2020
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Ingår i: International journal of plant sciences. - : University of Chicago Press. - 1058-5893 .- 1537-5315. ; 181, s. 887-897
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Tidskriftsartikel (refereegranskat)abstract
- remise of research. The Puddledock mesofossil flora from Virginia is the richest source for studying structurally preserved plant fossils in the Early Cretaceous Potomac Group sequence. Together with other mesofossil floras from the Potomac Group and also from Portugal, it is key for direct assessment of the structure, relationships, and reproductive biology of early angiosperms. In this study, a new multiparted floral structure from the Puddledock locality is analyzed, and its phylogenetic relationships are discussed.Methodology. The fossil was extracted from unconsolidated clays and sands through sieving in water. Adhering sediment was removed using HF and HCl followed by rinsing in water. External and internal features were studied using scanning electron microscopy and synchrotron radiation X-ray tomographic microscopy. Phylogenetic analyses were carried out by adding the features of the fossil flower to an existing morphological data set for extant angiosperms.Pivotal results. A new taxon, Melloniflora virginiensis gen. et sp. nov., is established on the basis of a small multiparted floral structure that has several series of free stamens (ca. 50) and carpels (21) borne on a flattened receptacle. Stamens have a broad, short base, and dehiscence is introrse. Ovules are borne in two rows on either side of the ventral suture of the carpels. Abundant secretory cells occur in all tissues. Melloniflora is related to extant early-diverging members of the Magnoliales but also has features found among extant taxa of other early-diverging angiosperm lineages such as Austrobaileyales.Conclusions. Melloniflora adds to the knowledge of plants related to extinct magnoliids from the Early Cretaceous. It shows a combination of features not seen in any extant taxon. Melloniflora contributes to the evidence of considerable extinct diversity at an early stage in angiosperm evolution, especially among clades that today are represented by only a few relatively species-poor lineages.
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| 6. |
- Friis, Else Marie, et al.
(författare)
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Microsporangiophores from the Early Cretaceous (Berriasian) of Bornholm, Denmark, with comments on a pre-angiosperm xerophytic flora
- 2021
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Ingår i: Review of Palaeobotany and Palynology. - Amsterdam : Elsevier. - 0034-6667 .- 1879-0615. ; 293
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Tidskriftsartikel (refereegranskat)abstract
- A new taxon, Skyttegaardia galtieri, is described based on microsporangiophores with Monosulcites/Cycadopites pollen isolated from clays collected at the Skyttegård locality, island of Bornholm, Denmark, which are of earliest Cretaceous (Berriasian) age. Each microsporangiophore consists of a short, massive proximal fertile stalk-like portion with a truncate base, and a long sterile distal extension. A cavity on each side of the median line of the stalk-like portion, partially encloses a sporangium that dehisces by a longitudinal slit. The long distal extension tapers to a slender point and is curved toward the inferred adaxial side. The extension is irregularly angular in cross-section and the cuticle is thick with deep stomatal pits. The organization of the microsporangiophore, the in situ pollen and stomatal features suggest relationship with extant Cycadales. However, in all extant and fossil cycads there are usually many more sporangia per microsporangiophore, typically in groups of two to five, and they are borne on the surface of the proximal stalk-like portion rather than embedded in its tissues. These differences preclude secure inclusion of Skyttegaardia in Cycadales and open the possibility that these microsporangiophores were produced by a group of extinct plants, the other parts of which remain to be identified. The thick cuticle and sunken stomata of Skyttegaardia, together with the embedded sporangia, suggest adaptation to water stress, which is also consistent with the xeromorphic traits seen among the leaf fragments in the Skyttegaard flora and the arid conditions inferred from geological–geochemical proxies.
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| 7. |
- Friis, Else Marie, et al.
(författare)
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Multiparted, apocarpous flowers from the Early Cretaceous of eastern North America and Portugal
- 2020
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Ingår i: Fossil Imprint. - Prague : Czech National Museum. - 2533-4069 .- 2533-4050. ; 76, s. 279-296
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Tidskriftsartikel (refereegranskat)abstract
- Three new genera, Atlantocarpus, Lambertiflora and Mugideiriflora, are described from the Early Cretaceous of North America and Portugal based on floral structures with multicarpellate and apocarpous gynoecia that have been studied using scanning electron microscopy and synchrotron radiation X-ray tomographic microscopy. Lambertiflora and Mugideiriflora have numerous perianth parts in several series, as well as many stamens and many carpels borne on a short conical receptacle. Atlantocarpus has many carpels arranged spirally on an elongated receptacle. Perianth and stamens are not preserved in Atlantocarpus, but scars of two sizes at the base of the receptacle indicate the presence of several series of tepals and stamens. Phylogenetic assessment of the three new genera indicates close relationships with members of extant Austrobaileyales, which is also favoured by the apparently ascidiate carpels of Atlantocarpus. However, the phylogenetic signal is not strong and the fossils also share many features with magnoliid angiosperms. Fully secure resolution of their relationships is hampered by lack of information of critical floral features in the fossil material, the constellation of likely plesiomorphic characters that they exhibit, and inadequate knowledge of character homologies and character evolution among extant taxa. There is also the broader concern about whether phylogenetic patterns can be reliably inferred for the earliest phases of angiosperm evolution based solely on a depauperate assemblage of extant taxa given extensive extinction over the last 100 million years. The new genera add to growing evidence of diverse extinct angiosperms with multiparted flowers during the Early Cretaceous that have a variety of relationships to extant ANA-grade angiosperms and magnoliids.
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