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The determinants of biodiversity patterns can be understood using macroevolutionary analyses. The integration of fossils into phylogenies offers a deeper understanding of processes underlying biodiversity patterns in deep time. Cycadales are considered a relict of a once more diverse and globally distributed group but are restricted to low latitudes today. We still know little about their origin and geographic range evolution. Combining molecular data for extant species and leaf morphological data for extant and fossil species, we study the origin of cycad global biodiversity patterns through Bayesian total-evidence dating analyses. We assess the ancestral geographic origin and trace the historical biogeography of cycads with a time-stratified process-based model. Cycads originated in the Carboniferous on the Laurasian landmass and expanded in Gondwana in the Jurassic. Through now-vanished continental connections, Antarctica and Greenland were crucial biogeographic crossroads for cycad biogeography. Vicariance is an essential speciation mode in the deep and recent past. Their latitudinal span increased in the Jurassic and restrained toward subtropical latitudes in the Neogene in line with biogeographic inferences of high-latitude extirpations. We show the benefits of integrating fossils into phylogenies to estimate ancestral areas of origin and to study evolutionary processes explaining the global distribution of present-day relict groups.

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Objectives: This study presents the Integrated Leaf Trait Analysis (ILTA), a workflow for the combined application of methodologies in leaf trait and insect herbivory analyses on fossil dicot leaf assemblages. The objectives were (1) to record the leaf morphological variability, (2) to describe the herbivory pattern on fossil leaves, (3) to explore relations between leaf morphological trait combination types (TCTs), quantitative leaf traits, and other plant characteristics (e.g., phenology), and (4) to explore relations of leaf traits and insect herbivory. Material and Methods: The leaves of the early Oligocene floras Seifhennersdorf (Saxony, Germany) and Suletice-Berand (Ústí nad Labem Region, Czech Republic) were analyzed. The TCT approach was used to record the leaf morphological patterns. Metrics based on damage types on leaves were used to describe the kind and extent of insect herbivory. The leaf assemblages were characterized quantitatively (e.g., leaf area and leaf mass per area (LMA)) based on subsamples of 400 leaves per site. Multivariate analyses were performed to explore trait variations. Results: In Seifhennersdorf, toothed leaves of TCT F from deciduous fossil-species are most frequent. The flora of Suletice-Berand is dominated by evergreen fossil-species, which is reflected by the occurrence of toothed and untoothed leaves with closed secondary venation types (TCTs A or E). Significant differences are observed for mean leaf area and LMA, with larger leaves tending to lower LMA in Seifhennersdorf and smaller leaves tending to higher LMA in Suletice-Berand. The frequency and richness of damage types are significantly higher in Suletice-Berand than in Seifhennersdorf. In Seifhennersdorf, the evidence of damage types is highest on deciduous fossil-species, whereas it is highest on evergreen fossil-species in Suletice-Berand. Overall, insect herbivory tends to be more frequently to occur on toothed leaves (TCTs E, F, and P) that are of low LMA. The frequency, richness, and occurrence of damage types vary among fossil-species with similar phenology and TCT. In general, they are highest on leaves of abundant fossil-species. Discussion: TCTs reflect the diversity and abundance of leaf architectural types of fossil floras. Differences in TCT proportions and quantitative leaf traits may be consistent with local variations in the proportion of broad-leaved deciduous and evergreen elements in the ecotonal vegetation of the early Oligocene. A correlation between leaf size, LMA, and fossil-species indicates that trait variations are partly dependent on the taxonomic composition. Leaf morphology or TCTs itself cannot explain the difference in insect herbivory on leaves. It is a more complex relationship where leaf morphology, LMA, phenology, and taxonomic affiliation are crucial.

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PREMISE: Angiosperm leaves present a classic identification problem due to their morphological complexity. Computer-vision algorithms can identify diagnostic regions in images, and heat map outputs illustrate those regions for identification, providing novel insights through visual feedback. We investigate the potential of analyzing leaf heat maps to reveal novel, human-friendly botanical information with applications for extant- and fossil-leaf identification. METHODS: We developed a manual scoring system for hotspot locations on published computer-vision heat maps of cleared leaves that showed diagnostic regions for family identification. Heat maps of 3114 cleared leaves of 930 genera in 14 angiosperm families were analyzed. The top-5 and top-1 hotspot regions of highest diagnostic value were scored for 21 leaf locations. The resulting data were viewed using box plots and analyzed using cluster and principal component analyses. We manually identified similar features in fossil leaves to informally demonstrate potential fossil applications. RESULTS: The method successfully mapped machine strategy using standard botanical language, and distinctive patterns emerged for each family. Hotspots were concentrated on secondary veins (Salicaceae, Myrtaceae, Anacardiaceae), tooth apices (Betulaceae, Rosaceae), and on the little-studied margins of untoothed leaves (Rubiaceae, Annonaceae, Ericaceae). Similar features drove the results from multivariate analyses. The results echo many traditional observations, while also showing that most diagnostic leaf features remain undescribed. CONCLUSIONS: Machine-derived heat maps that initially appear to be dominated by noise can be translated into human-interpretable knowledge, highlighting paths forward for botanists and paleobotanists to discover new diagnostic botanical characters.

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PREMISE: Nearly 200 araceous leaves and two spadices have been identified among Paleocene fossils from the Blindman River locality near Blackfalds, Alberta, Canada. Although not found in attachment, these probably represent parts of the same extinct plant species. METHODS: Specimens were studied using light microscopy. Phylogenetic analyses using a morphological matrix of living and fossil Araceae were performed using TNT version 1.5 to help establish relationships of the fossil leaves and spadices within Araceae and to each other. RESULTS: Leaves are simple with a broad petiole, entire margin, and elliptic to ovate or oblong blade with an acute to slightly rounded apex. A multi-veined midrib extends into the basal region of the blade. Parallelodromous primary veins of two orders diverge at acute angles, converging with a submarginal vein or at the apex. Transverse veins are opposite percurrent, producing rectangular to polygonal areoles. Higher-order veins are mixed opposite/alternate. Spadices are cylindrical, with helically arranged, bisexual, perigoniate flowers, each with six free tepals and a protruding style. Fruits are trilocular, with axile placentation and one seed per locule. CONCLUSIONS: Leaves are assignable to the fossil genus Orontiophyllum J. Kvacek & S.Y. Sm. as O. grandifolium comb. nov. Spadices are described as Bognerospadix speirsiae gen. et sp. nov. Leaves and spadices each conform to an early-diverging lineage of Araceae, increasing the known diversity of Proto-Araceae (viz., subfamilies Gymnostachydoideae and Orontioideae). Together, they provide strong evidence for extinct Proto-Araceae with novel combinations of characters shortly after the Cretaceous-Paleogene floral transition.

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Leaves are the most abundant and visible plant organ, both in the modern world and the fossil record. Identifying foliage to the correct plant family based on leaf architecture is a fundamental botanical skill that is also critical for isolated fossil leaves, which often, especially in the Cenozoic, represent extinct genera and species from extant families. Resources focused on leaf identification are remarkably scarce; however, the situation has improved due to the recent proliferation of digitized herbarium material, live-plant identification applications, and online collections of cleared and fossil leaf images. Nevertheless, the need remains for a specialized image dataset for comparative leaf architecture. We address this gap by assembling an open-access database of 30,252 images of vouchered leaf specimens vetted to family level, primarily of angiosperms, including 26,176 images of cleared and x-rayed leaves representing 354 families and 4,076 of fossil leaves from 48 families. The images maintain original resolution, have user-friendly filenames, and are vetted using APG and modern paleobotanical standards. The cleared and x-rayed leaves include the Jack A. Wolfe and Leo J. Hickey contributions to the National Cleared Leaf Collection and a collection of high-resolution scanned x-ray negatives, housed in the Division of Paleobotany, Department of Paleobiology, Smithsonian National Museum of Natural History, Washington D.C.; and the Daniel I. Axelrod Cleared Leaf Collection, housed at the University of California Museum of Paleontology, Berkeley. The fossil images include a sampling of Late Cretaceous to Eocene paleobotanical sites from the Western Hemisphere held at numerous institutions, especially from Florissant Fossil Beds National Monument (late Eocene, Colorado), as well as several other localities from the Late Cretaceous to Eocene of the Western USA and the early Paleogene of Colombia and southern Argentina. The dataset facilitates new research and education opportunities in paleobotany, comparative leaf architecture, systematics, and machine learning.

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Resumen El Bosque Petrificado Piedra Chamana, cerca del pueblo de Sexi en Cajamarca, registra la vegetación de los trópicos de Sudamérica de hace 39 millones de años, la que existió en los inicios de la historia de los bosques tropicales del Nuevo Mundo y antes del levantamiento de los Andes. En este bosque, descubrimientos notables incluyen el manglar del género Avicennia, un género de árboles forestales emergentes (Cynometra), y el segundo dipterocarp conocido del Nuevo Mundo. La importancia de los fósiles se basa en sus circunstancias únicas de preservación, es así como fósiles de plantas y suelos antiguos permiten la reconstrucción detallada del bosque y el medio ambiente en que existieron, contribuyendo con el conocimiento del cambio climático. Los sitios como este bosque fósil son muy vulnerables al disturbio y pérdida de los recursos fósiles. El monitoreo muestra que las actividades humanas y la erosión están teniendo efectos serios y que son necesarias medidas urgentes para su conservación. La importancia de los fósiles para la ciencia, la belleza de esta área de los Andes, y el potencial para la educación y turismo justifican el reconocimiento del Bosque Petrificado Piedra Chamana a nivel internacional. El bosque tropical representado por los fósiles es muy diferente del bosque diverso esclerófilo de hoja ancha que se encuentra actualmente en el sitio. La pérdida del suelo y la erosión del substrato suave y poroso por alteración de la cubierta vegetal son una amenaza para la biota nativa y los fósiles. Por lo tanto, las medidas de conservación necesarias para proteger los fósiles tendrían múltiples beneficios para la ecología del área.

Abstract The Piedra Chamana Fossil Forest, near the village of Sexi in central Cajamarca, records the vegetation of the South American tropics 39 million years ago, early in the New World tropical forests history and before the rise of the present-day Andes. In this fossil forest, notable discoveries have included the mangrove genus Avicennia, a genus of emergent forest trees (Cynometra), and the second dipterocarp known from the New World. The significance of the fossils rests on the unique circumstances of preservation, the detailed reconstruction of the forest and environment that is possible based on the plant fossils and ancient soils, and the importance of this record for the study of climate change. Sites like the fossil forest are particularly vulnerable to disturbance and loss of the fossil resources. Ongoing monitoring shows that human activities and erosion are having serious effects and, conservation measures are urgently needed. The importance of the fossils for science, the beauty of this area of the Andes, and the potential of the site for education and tourism justify recognition of the fossil forest at an international level. The lowland tropical forest represented by the fossils is very different from the diverse broad-leaf sclerophyllous forest or woodland now growing in the area. Soil loss and erosion of the soft, porous volcanic substrate when the vegetation cover is disturbed poses a threat to both the native biota and the fossils. The conservation measures needed at the fossil site would have multiple benefits for the ecology of the region.

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Fossil plant gas-exchange-based CO2 reconstructions use carbon (C) assimilation rates of extant plant species as substitutes for assimilation rates of fossil plants. However, assumptions in model species adoption can lead to systematic error propagation. We used a dataset of c. 2500 extant species to investigate the role of phylogenetic relatedness and ecology in determining C assimilation, an essential variable in gas-exchange-based CO2 models. We evaluated the effect on random and systematic error propagation in atmospheric CO2 caused by adopting different model species. Phylogenetic relatedness, growth form, and solar exposure are important predictors of C assimilation rate. CO2 reconstructions that apply C assimilation rates from modern species based solely on phylogenetic relatedness to fossil species can result in CO2 estimates that are systematically biased by a factor of > 2. C assimilation rates used in CO2 reconstructions should be determined by averaging assimilation rates of modern plant species that are (1) in the same family and (2) have a similar habit and habitat as the fossil plant. In addition, systematic bias potential and random error propagation are greatly reduced when CO2 is reconstructed from multiple fossil plant species with different modern relatives at the same site.

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PREMISE OF THE STUDY: The history of the basal angiosperm family Monimiaceae is based largely on fossil wood and leaf and floral fossils of uncertain affinity. Fossilized leaves with a well-preserved cuticle and Hedycarya-like flowers, including one with in situ pollen tetrads and fruits from an early Miocene lacustrine diatomite deposit in southern New Zealand implies a long record for Hedycarya in New Zealand. The flowers contain pollen grains that are very similar to those of the modern New Zealand species Hedycarya arborea and the Australian H. angustifolia but are considerably smaller. METHODS: We undertook comparative studies of the leaf, flower and fruit morphology of the newly discovered macrofossils and compared the in situ pollen grains from the flower with dispersed pollen grains from extant species. KEY RESULTS: The leaves are referred to a new, extinct species, Hedycarya pluvisilva Bannister, Conran, Mildenh. & D.E.Lee, (Monimiaceae), and associated with fossilized Hedycarya-like flowers that include in situ pollen and an infructescence of three drupes from the same site. Phylogenetic analysis placed the fossil into Hedycarya, sister to H. angustifolia in a clade with H. arborea and Levieria acuminata. A new name, Planarpollenites fragilis Mildenh., is proposed for dispersed fossil pollen tetrads at the site and those associated with the flower. CONCLUSIONS: The fossils are similar to those of modern Australian and New Zealand Hedycarya species, suggesting that the genus and related taxa have been significant components of the rainforests of Australia and the former Zealandian subcontinent for most of the Cenozoic.

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PREMISE OF THE STUDY: Documented fossil floras in the neotropics are sparse, yet their records provide evidence on the spatial and temporal occurrence of taxa, allowing for testing of biogeographical and diversification scenarios on individual lineages. A new fossil Piper from the Late Cretaceous of Colombia is described here, and its importance for assessing diversification patterns in the genus is addressed. METHODS: Leaf architecture of 32 fossil leaf compressions from the Guaduas Formation was compared with that of 294 extant angiosperm species. The phylogenetic position of the fossil named Piper margaritae sp. nov. was established based on leaf traits and a molecular scaffold of Piper. The age of the fossil was independently used as a calibration point for divergence time estimations. KEY RESULTS: Natural affinities of P. margaritae to the Schilleria clade of Piper indicate that the genus occurred in tropical America by the Late Cretaceous. Estimates of age divergence and lineage accumulation reveal that most of the extant diversity of the genus accrued during the last ∼30 Myr. CONCLUSIONS: The recent radiation of Piper is coeval with both the Andean uplift and the emergence of Central America, which have been proposed as important drivers of diversity. This pattern could exemplify a recurrent theme among many neotropical plant lineages.

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