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Bickner MA, Herrera F, Shi G, Ichinnorov N, Crane PR, Herendeen PS. Mongolitria: A new Early Cretaceous three-valved seed from Northeast Asia. AMERICAN JOURNAL OF BOTANY 2024; 111:e16268. [PMID: 38050806 DOI: 10.1002/ajb2.16268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 11/03/2023] [Accepted: 11/06/2023] [Indexed: 12/06/2023]
Abstract
PREMISE Fossil seeds recovered from the Early Cretaceous of Mongolia and Inner Mongolia, China, are described and assigned to Mongolitria gen. nov., a new genus of gymnosperm seed. METHODS Abundant lignitized seeds along with compression specimens isolated from the matrix were studied using a combination of scanning electron microscopy, anatomical sectioning, light microscopy, synchrotron radiation X-ray microtomography, and cuticle preparations. A single permineralized seed was examined by light microscopy of cellulose acetate peels and X-ray microtomography. RESULTS Two species are recognized, Mongolitria friisae sp. nov. and Mongolitria exesum sp. nov. Both seeds are orthotropous with a short apical micropyle and a small, basal, circular attachment scar. The thick sclerenchymatous integument has a consistently three-parted organization and about 20 conspicuous longitudinal ribs on the surface. Mongolitria exesum differs from M. friisae primarily in its much larger size and thicker seed coat, which also preserves clear evidence of insect damage. CONCLUSIONS Mongolitria is similar to other fossil seeds that have been assigned to Cycadales, but displays a unique combination of characters not found in any living or extinct cycadaceous plant, leaving its higher-level systematic affinities uncertain. Germination apparently involved splitting of the integument into three valves. Mongolitria was prominent among the plant parts accumulating in peat swamps in eastern Asia during the Early Cretaceous.
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Affiliation(s)
| | - Fabiany Herrera
- Earth Sciences, Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, 60605, Illinois, USA
| | - Gongle Shi
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing, 210008, People's Republic of China
| | - Niiden Ichinnorov
- Institute of Paleontology and Geology, Mongolian Academy of Sciences, Ulaanbaatar-51, Mongolia
| | - Peter R Crane
- Oak Spring Garden Foundation, Upperville, 20184, Virginia, USA
- Yale School of the Environment, Yale University, New Haven, 06511, Connecticut, USA
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Huntsman SV, Leslie AB. The ontogeny of disparity in Cupressaceae seed cones. THE NEW PHYTOLOGIST 2023. [PMID: 38148572 DOI: 10.1111/nph.19482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 11/25/2023] [Indexed: 12/28/2023]
Abstract
Ontogenetic shape change has long been recognized to be important in generating patterns of morphological diversity and may be especially important in plant reproductive structures. We explore how seed cone disparity in Cupressaceae changes over ontogeny by comparing pollination-stage and mature cones. We sampled cones at pollen and seed release and measured cone scales using basic morphometric shape variables. We used multivariate statistical methods, particularly hypervolume overlap calculations, to measure morphospace occupation and disparity. Cone scales at both pollination and maturity exhibit substantial variability, although the disparity is greater at maturity. Mature cone scales are also more clustered in trait space, showing less overlap with other taxa than at pollination. These patterns reflect two growth strategies that generate closed cones over maturation, either through thin laminar scales or relatively thick, peltate scales, resulting in two distinct regions of morphospace occupation. Disparity patterns in Cupressaceae seed cones change over ontogeny, reflecting shifting functional demands that require specific patterns of cone scale growth. The evolution of Cupressaceae reproductive disparity therefore represents selection for trajectories of ontogenetic shape change, a phenomenon that should be widespread across seed plants.
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Affiliation(s)
- Stepfan V Huntsman
- Department of Earth and Planetary Sciences, Stanford University, 450 Jane Stanford Way, Building 320, Room 118, Stanford, CA, 94305, USA
| | - Andrew B Leslie
- Department of Earth and Planetary Sciences, Stanford University, 450 Jane Stanford Way, Building 320, Room 118, Stanford, CA, 94305, USA
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Herrera F, Shi G, Bickner MA, Ichinnorov N, Leslie AB, Crane PR, Herendeen PS. Early Cretaceous abietoid Pinaceae from Mongolia and the history of seed scale shedding. AMERICAN JOURNAL OF BOTANY 2021; 108:1483-1499. [PMID: 34458982 DOI: 10.1002/ajb2.1713] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 03/10/2021] [Indexed: 06/13/2023]
Abstract
PREMISE Seed cones of extant Pinaceae exhibit two mechanisms of seed release. In "flexers" the cone scales remain attached to the central axis, while flexing and separating from each other to release the seeds. In "shedders" scales are shed from the axis, with the seeds either remaining attached to the scale or becoming detached. The early fossil history of Pinaceae from the Jurassic to Early Cretaceous is dominated by flexing seed cones, while the systematic information provided by shedding fossil cones has been overlooked and rarely integrated with data based on compression and permineralized specimens. We describe the earliest and best-documented evidence of a "shedder" seed cone from the Aptian-Albian of Mongolia. METHODS Lignite samples from Tevshiin Govi locality were disaggregated in water, washed, and dried in air. Fossils were compared to material of extant Pinaceae using LM and CT scans. RESULTS Lepidocasus mellonae gen. et sp. nov. is characterized by a seed cone that disarticulated at maturity and shed obovate bract-scale complexes that have a distinctive ribbed surface and an abaxial surface covered with abundant trichomes. The ovuliferous scale has ca. 30-40 resin canals, but only scarce xylem near the attachment to the cone axis. Resin vesicles are present in the seed integument. Phylogenetic analysis places Lepidocasus as sister to extant Cedrus within the abietoid grade. CONCLUSIONS The exquisite preservation of the trichomes in L. mellonae raises questions about their potential ecological function in the cones of fossil and living Pinaceae. Lepidocasus mellonae also shows that a shedding dispersal syndrome, a feature that has often been overlooked, evolved early in the history of Pinaceae during the Early Cretaceous.
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Affiliation(s)
| | - Gongle Shi
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing, 210008, China
| | | | - Niiden Ichinnorov
- Institute of Paleontology, Mongolian Academy of Sciences, Ulaanbaatar-15160, Mongolia
| | - Andrew B Leslie
- Department of Geological Sciences, Stanford University, California, 94305, USA
| | - Peter R Crane
- Oak Spring Garden Foundation, Oak Spring, Upperville, Virginia, 20184, USA
- Yale School of the Environment, Yale University, New Haven, Connecticut, 06511, USA
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Herrera F, Shi G, Mays C, Ichinnorov N, Takahashi M, Bevitt JJ, Herendeen PS, Crane PR. Reconstructing Krassilovia mongolica supports recognition of a new and unusual group of Mesozoic conifers. PLoS One 2020; 15:e0226779. [PMID: 31940374 PMCID: PMC6961850 DOI: 10.1371/journal.pone.0226779] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 12/03/2019] [Indexed: 11/19/2022] Open
Abstract
Previously unrecognized anatomical features of the cone scales of the enigmatic Early Cretaceous conifer Krassilovia mongolica include the presence of transversely oriented paracytic stomata, which is unusual for all other extinct and extant conifers. Identical stomata are present on co-occurring broad, linear, multiveined leaves assigned to Podozamites harrisii, providing evidence that K. mongolica and P. harrisii are the seed cones and leaves of the same extinct plant. Phylogenetic analyses of the relationships of the reconstructed Krassilovia plant place it in an informal clade that we name the Krassilovia Clade, which also includes Swedenborgia cryptomerioides-Podozamites schenkii, and Cycadocarpidium erdmanni-Podozamites schenkii. All three of these plants have linear leaves that are relatively broad compared to most living conifers, and that are also multiveined with transversely oriented paracytic stomata. We propose that these may be general features of the Krassilovia Clade. Paracytic stomata, and other features of this new group, recall features of extant and fossil Gnetales, raising questions about the phylogenetic homogeneity of the conifer clade similar to those raised by phylogenetic analyses of molecular data.
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Affiliation(s)
- Fabiany Herrera
- Chicago Botanic Garden, Glencoe, Illinois, United States of America
| | - Gongle Shi
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing, People’s Republic of China
| | - Chris Mays
- Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden
- School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria, Australia
| | - Niiden Ichinnorov
- Institute of Paleontology and Geology, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia
| | - Masamichi Takahashi
- Department of Environmental Sciences, Faculty of Science, Niigata University, Nishi-ku, Niigata, Japan
| | - Joseph J. Bevitt
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, New South Wales, Australia
| | | | - Peter R. Crane
- Oak Spring Garden Foundation, Upperville, Virginia, United States of America
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut, United States of America
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Leslie AB, Beaulieu J, Holman G, Campbell CS, Mei W, Raubeson LR, Mathews S. An overview of extant conifer evolution from the perspective of the fossil record. AMERICAN JOURNAL OF BOTANY 2018; 105:1531-1544. [PMID: 30157290 DOI: 10.1002/ajb2.1143] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 05/29/2018] [Indexed: 05/07/2023]
Abstract
PREMISE OF THE STUDY Conifers are an important living seed plant lineage with an extensive fossil record spanning more than 300 million years. The group therefore provides an excellent opportunity to explore congruence and conflict between dated molecular phylogenies and the fossil record. METHODS We surveyed the current state of knowledge in conifer phylogenetics to present a new time-calibrated molecular tree that samples ~90% of extant species diversity. We compared phylogenetic relationships and estimated divergence ages in this new phylogeny with the paleobotanical record, focusing on clades that are species-rich and well known from fossils. KEY RESULTS Molecular topologies and estimated divergence ages largely agree with the fossil record in Cupressaceae, conflict with it in Araucariaceae, and are ambiguous in Pinaceae and Podocarpaceae. Molecular phylogenies provide insights into some fundamental questions in conifer evolution, such as the origin of their seed cones, but using them to reconstruct the evolutionary history of specific traits can be challenging. CONCLUSIONS Molecular phylogenies are useful for answering deep questions in conifer evolution if they depend on understanding relationships among extant lineages. Because of extinction, however, molecular datasets poorly sample diversity from periods much earlier than the Late Cretaceous. This fundamentally limits their utility for understanding deep patterns of character evolution and resolving the overall pattern of conifer phylogeny.
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Affiliation(s)
- Andrew B Leslie
- Department of Ecology and Evolutionary Biology, Brown University, Box G-W, 80 Waterman Street, Providence, Rhode Island, 02912, USA
| | - Jeremy Beaulieu
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas, 72701, USA
| | - Garth Holman
- School of Biology and Ecology, University of Maine, Orono, Maine, 04469, USA
| | | | - Wenbin Mei
- Department of Plant Sciences, University of California, Davis, 1 Shields Avenue, Davis, California, 95616, USA
| | - Linda R Raubeson
- Department of Biological Sciences, Central Washington University, 400 E. University Way, Ellensburg, Washington, 98926, USA
| | - Sarah Mathews
- CSIRO National Research Collections Australia, Australian National Herbarium, Canberra, ACT, 2601, Australia
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Herrera F, Moran RC, Shi G, Ichinnorov N, Takahashi M, Crane PR, Herendeen PS. An exquisitely preserved filmy fern (Hymenophyllaceae) from the Early Cretaceous of Mongolia. AMERICAN JOURNAL OF BOTANY 2017; 104:1370-1381. [PMID: 29885232 DOI: 10.3732/ajb.1700246] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 08/25/2017] [Indexed: 06/08/2023]
Abstract
PREMISE OF THE STUDY Hymenophyllaceae ("filmy ferns") are a widely distributed group of predominantly tropical, epiphytic ferns that also include some temperate and terrestrial species. Hymenophyllaceae are one of the earliest-diverging lineages within leptosporangiate ferns, but their fossil record is sparse, most likely because of their low fossilization potential and commonly poor preservation of their delicate, membranaceous fronds. A new species of unequivocal fossil Hymenophyllaceae, Hymenophyllum iwatsukii sp. nov., is described from the Early Cretaceous of Mongolia based on abundant and exceptionally well-preserved material. METHODS Bulk lignite samples collected from Tevshiin Govi and Tugrug localities in Mongolia, were disaggregated in water, cleaned with hydrochloric and hydrofluoric acids, washed, and dried in air. Fossils were examined and compared to material of extant Hymenophyllaceae using LM and SEM. KEY RESULTS The fossil fern specimens are assigned to the Hymenophyllaceae based on their membranaceous laminae with marginal sori that have sessile to short-stalked sporangia with oblique, complete annuli, and trilete, tetrahedral-globose spores. Within the family, the fossil material is assigned to the extant genus Hymenophyllum on the basis of bivalvate indusia and short, included receptacles. CONCLUSIONS Hymenophyllum iwatsukii was likely an epiphyte based on the sedimentary environment in which the fossils are preserved, the associated fossil flora, and the growth habit of extant species of Hymenophyllum. The new fossil species underlines the extent to which morphological characters in Hymenophyllum have been conserved despite significant tectonic, climatic, ecological, and floristic changes since the Early Cretaceous.
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Affiliation(s)
| | - Robbin C Moran
- The New York Botanical Garden, Bronx, New York 10458 USA
| | - Gongle Shi
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008 People's Republic of China
| | - Niiden Ichinnorov
- Institute of Paleontology and Geology, Mongolian Academy of Sciences, Ulaanbaatar-51, Mongolia
| | - Masamichi Takahashi
- Department of Environmental Sciences, Niigata University, Ikarashi, Nishi-ku, Niigata 950-2181 Japan
| | - Peter R Crane
- Oak Spring Garden Foundation, Oak Spring, Upperville, Virginia 20184 USA
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511 USA
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Herrera F, Shi G, Ichinnorov N, Takahashi M, Bugdaeva EV, Herendeen PS, Crane PR. The presumed ginkgophyte Umaltolepis has seed-bearing structures resembling those of Peltaspermales and Umkomasiales. Proc Natl Acad Sci U S A 2017; 114:E2385-E2391. [PMID: 28265050 PMCID: PMC5373332 DOI: 10.1073/pnas.1621409114] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The origins of the five groups of living seed plants, including the single relictual species Ginkgo biloba, are poorly understood, in large part because of very imperfect knowledge of extinct seed plant diversity. Here we describe well-preserved material from the Early Cretaceous of Mongolia of the previously enigmatic Mesozoic seed plant reproductive structure Umaltolepis, which has been presumed to be a ginkgophyte. Abundant new material shows that Umaltolepis is a seed-bearing cupule that was borne on a stalk at the tip of a short shoot. Each cupule is umbrella-like with a central column that bears a thick, resinous, four-lobed outer covering, which opens from below. Four, pendulous, winged seeds are attached to the upper part of the column and are enclosed by the cupule. Evidence from morphology, anatomy, and field association suggests that the short shoots bore simple, elongate Pseudotorellia leaves that have similar venation and resin ducts to leaves of living GinkgoUmaltolepis seed-bearing structures are very different from those of Ginkgo but very similar to fossils described previously as Vladimaria. Umaltolepis and Vladimaria do not closely resemble the seed-bearing structures of any living or extinct plant, but are comparable in some respects to those of certain Peltaspermales and Umkomasiales (corystosperms). Vegetative similarities of the Umaltolepis plant to Ginkgo, and reproductive similarities to extinct peltasperms and corystosperms, support previous ideas that Ginkgo may be the last survivor of a once highly diverse group of extinct plants, several of which exhibited various degrees of ovule enclosure.
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Affiliation(s)
| | - Gongle Shi
- Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, People's Republic of China
| | - Niiden Ichinnorov
- Institute of Paleontology and Geology, Mongolian Academy of Sciences, Ulaanbaatar-51, Mongolia
| | - Masamichi Takahashi
- Department of Environmental Sciences, Faculty of Sciences, Niigata University, Ikarashi, Nishi-ku, Niigata 950-2181, Japan
| | - Eugenia V Bugdaeva
- Institute of Biology and Soil Science, Far East Branch, Russian Academy of Sciences, Vladivostok 690022, Russia
| | | | - Peter R Crane
- School of Forestry and Environmental Studies, Yale University, New Haven, CT 06511;
- Oak Spring Garden Foundation, Oak Spring, Upperville, VA 20184
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Shi G, Leslie AB, Herendeen PS, Herrera F, Ichinnorov N, Takahashi M, Knopf P, Crane PR. Early Cretaceous Umkomasia from Mongolia: implications for homology of corystosperm cupules. THE NEW PHYTOLOGIST 2016; 210:1418-29. [PMID: 26840646 DOI: 10.1111/nph.13871] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2015] [Accepted: 12/17/2015] [Indexed: 05/21/2023]
Abstract
Corystosperms, a key extinct group of Late Permian to Early Cretaceous plants, are important for understanding seed plant phylogeny, including the evolution of the angiosperm carpel and anatropous bitegmic ovule. Here, we describe a new species of corystosperm seed-bearing organ, Umkomasia mongolica sp. nov., based on hundreds of three-dimensionally preserved mesofossils from the Early Cretaceous of Mongolia. Individual seed-bearing units of U. mongolica consist of a bract subtending an axis that bifurcates, with each fork (cupule stalk) bearing a cupule near the tip. Each cupule is formed by the strongly reflexed cupule stalk and two lateral flaps that partially enclose an erect seed. The seed is borne at, or close to, the tip of the reflexed cupule stalk, with the micropyle oriented towards the stalk base. The corystosperm cupule is generally interpreted as a modified leaf that bears a seed on its abaxial surface. However, U. mongolica suggests that an earlier interpretation, in which the seed is borne directly on an axis (shoot), is equally likely. The 'axial' interpretation suggests a possible relationship of corystosperms to Ginkgo. It also suggests that the cupules of corystosperms may be less distinct from those of Caytonia than has previously been supposed.
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Affiliation(s)
- Gongle Shi
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing, 210008, China
- School of Forestry and Environmental Studies, Yale University, 195 Prospect Street, New Haven, CT, 06511, USA
| | - Andrew B Leslie
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, 02912, USA
| | | | - Fabiany Herrera
- Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL, 60022, USA
| | - Niiden Ichinnorov
- Paleontological Center, Mongolian Academy of Sciences, PO Box 260, Ulaanbaatar-51, Mongolia
| | - Masamichi Takahashi
- Department of Environmental Sciences, Faculty of Sciences, Niigata University, 8050, 2-cho, Ikarashi, Nishi-ku, Niigata, 950-2181, Japan
| | - Patrick Knopf
- Botanischer Garten Rombergpark, Am Rombergpark 49b, Dortmund, 44225, Germany
| | - Peter R Crane
- School of Forestry and Environmental Studies, Yale University, 195 Prospect Street, New Haven, CT, 06511, USA
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