Leaf Impressions Research Articles

New records for the Middle Siwalik flora of eastern Nepal and their climatic significance

The Siwalik plant fossils are important in understanding the climate change caused by the uplift of the Himalaya. The plant fossil assemblages are abundantly known from Nepal's central and western Siwalik sediments. However, they are poorly known from the Siwalik of the eastern region from where the modern Indian Summer Monsoon (ISM) enters Nepal. That is why fossils of this region are important in understanding the evolutionary history of ISM in Nepal. In the present communication, we report four new fossil leaf impressions/ compressions, namely Thelypteridaceophyllum tertiarum Joshi and Mehrotra of the family Thelypteridaceae, Calophyllum suraikholaensis Awasthi and Prasad of the Calophyllaceae, Albizia siwalica Prasad of the family Fabaceae, and Daphnogene makumensis Mehrotra, Dilcher et Lott of the family Lauraceae from the well-dated Middle Siwalik (∼9.5 Ma) sediments of eastern Nepal. The aforementioned and previous fossil records suggest that seasonal or monsoonal rainfall was present during the deposition of the sediments.

Responses of stomatal density and carbon isotope composition of sugar maple and yellow birch foliage to N, P and CaSiO3 fertilization.

Stomatal density, stomatal length and carbon isotope composition can all provide insights into environmental controls on photosynthesis and transpiration. Stomatal measurements can be time-consuming; it is therefore wise to consider efficient sampling schemes. Knowing the variance partitioning at different measurement levels (i.e., among stands, plots, trees, leaves and within leaves) can aid in making informed decisions around where to focus sampling effort. In this study, we explored the effects of nitrogen (N), phosphorus (P) and calcium silicate (CaSiO3) addition on stomatal density, length and carbon isotope composition (δ13C) of sugar maple (Acer saccharum Marsh.) and yellow birch (Betula alleghaniensis Britton). We observed a positive but small (8%) increase in stomatal density with P addition and an increase in δ13C with N and CaSiO3 addition in sugar maple, but we did not observe effects of nutrient addition on these characteristics in yellow birch. Variability was highest within leaves and among trees for stomatal density and highest among stomata for stomatal length. To reduce variability and increase chances of detecting treatment differences in stomatal density and length, future protocols should consider pretreatment and repeated measurements of trees over time or measure more trees per plot, increase the number of leaf impressions or standardize their locations, measure more stomata per image and ensure consistent light availability.

Marginal leaf galls on Pliocene leaves from India indicate mutualistic behavior between Ipomoea plants and Eriophyidae mites

We report a new type of fossil margin galls arranged in a linear series on dicot leaf impressions from the latest Neogene (Pliocene) sediments of the Chotanagpur Plateau, Jharkhand, eastern India. We collected ca. 1500 impression and compression leaf fossils, of which 1080 samples bear arthropod damage referable to 37 different damage types (DT) in the ‘GuidetoInsect(andOther)DamageTypesinCompressedPlantFossils’. A few leaf samples identified as Ipomoea L. (Convolvulaceae) have specific margin galls that do not match any galling DT previously described. This type of galling is characterized by small, linearly arranged, irregular, sessile, sub-globose, solitary, indehiscent, solid pouch-galls with irregular ostioles. The probable damage inducers of the present galling of the foliar margin might be members of Eriophyidae (Acari). The new type of gall suggests that marginal gall-inducing mites on leaves of Ipomoea did not change their host preference at the genus level since the Pliocene. The development of marginal leaf galling in Ipomoea is linked to extrafloral nectaries that do not offer protection against arthropod galling but indirectly protect the plant against herbivory from large mammals.

An Eocene leaf flora from the northern Peruvian Andes

The fossil forest known as El Bosque Petrificado Piedra Chamana lies in close proximity to the village of Sexi in the Department of Cajamarca in northern Peru. The forest was deposited in either a lahar or pyroclastic flow, and ashfall deposits, as mineralized wood and leaf impressions 39 million years ago (late Middle Eocene). More than 30 types of non-monocot angiosperms have been described from the fossil wood, which is densely embedded in rock outcrops, scattered across the ground, and occasionally found in situ. Anatomical characteristics and identifications of the woods suggest a seasonally flooded lowland tropical forest with a dry period. This site also preserves a small leaf flora which has not received a full treatment in earlier works and is the focus of the present study. The leaves are described in detail using standard leaf architecture terminology. The flora has 31 non-monocot leaf morphotypes. The presence of more than 30 morphotypes suggests high diversity based on having only ∼210 non-monocot leaf specimens. The leaf collection also includes ∼10 monocot specimens. One of the leaf morphotypes shows similarities to the extant mangrove genus Avicennia, possibly confirming one of the fossil wood identifications. Most of the leaves are incomplete, but when the margin is preserved, it is untoothed. The lack of teeth indicates a warm, tropical climate (estimated mean annual temperature of >25 °C based on leaf margin analysis). Leaves in the collection are small with 28 of 31 morphotypes inferred as microphyll or notophyll in laminar size, providing support for the seasonal dryness indicated by the fossil woods. Despite the small size of the collection, this leaf flora is important to document as there are few Eocene plant macrofossil localities in Peru; it provides some insight into the Cenozoic forests in this understudied region.

Non-avian theropod phalanges from the marine Fox Hills Formation (Maastrichtian), western South Dakota, USA.

We report here the first dinosaur skeletal material described from the marine Fox Hills Formation (Maastrichtian) of western South Dakota. The find consists of two theropod pedal phalanges: one recovered from the middle part of the Fairpoint Member in Meade County, South Dakota; and the other from the Iron Lightning Member in Ziebach County, South Dakota. Comparison with pedal phalanges of other theropods suggests strongly that the Fairpoint specimen is a right pedal phalanx, possibly III-2, from a large ornithomimid. The Iron Lightning specimen we cautiously identify as an ornithomimid left pedal phalanx II-2. The Fairpoint bone comes from thinly bedded and cross-bedded marine sandstones containing large hematitic concretions and concretionary horizons. Associated fossils include osteichthyan teeth, fin spines and otoliths, and abundant teeth of common Cretaceous nearshore and pelagic chondrichthyans. Leaf impressions and other plant debris, blocks of fossilized wood, and Ophiomorpha burrows are also common. The Iron Lightning bone comes from a channel deposit composed of fine to coarse sandstone beds, some of which contain bivalves, and a disseminated assemblage of mammal teeth, chondrichthyan teeth, and fragmentary dinosaur teeth and claws. We interpret the depositional environment of the two specimens as marginal marine. The Fairpoint bone derives from a nearshore foreset setting, above wave base subject to tidal flux and storm activity. The Iron Lightning specimen comes from a topset channel infill probably related to deposition on a tidal flat or associated coastal setting. The taphonomic history and ages of the two bones differ. Orthogonal cracks in the cortical bone of the Fairpoint specimen suggest post-mortem desiccation in a dryland coastal setting prior to transport and preservation in the nearby nearshore setting described above. The pristine surface of the Iron Lightning specimen indicates little transport before incorporation into the channel deposit in which it was found. The Fairpoint bone bed most probably lies within the Hoploscaphites nicolletii Ammonite Zone of the early late Maastrichtian, and would therefore have an approximate age of 69 Ma. The Iron Lightning bone is from the overlying H. nebrascensis Ammonite Zone, and is thus about one million years younger.

Taphonomic overprinting on the late Palaeozoic terrestrial plant–animal interactions: a noise in the record

Plant–animal interactions investigated largely in Glossopteris leaf fossils (1214 specimens) from the lower Permian strata of peninsular India reveal evidence of taphonomic modifications of the ichnofabric. The leaf fossils indicate both above-ground (pre-depositional) and on-ground (post-depositional) animal activities. Animal traces that extend beyond the margins of the leaf compressions or are emplaced on the leaf impressions are evidently post-depositional, preserved ex situ. Both feeding (herbivory/detritivory) and locomotary animal traces are interpreted in the host media. Preserved traces in the leaf fossils depict arrays of pre- and post-depositional events (viz., biotic interactions on green foliage, leaf detachment from the trees, post-mortem transport and burial) along taphonomic pathways. Accordingly, five taphonomic pathways are proposed based on varied combinations of pre- and post-depositional traces, emplaced on leaf fossils. Low diversity and persistent rarity of post-depositional traces (4%) as compared to more common pre-depositional traces (7%) in the sample population are noted. Less common post-depositional trace fossil assemblages of depauperate diversity indicate that stressed habitats prevailed at the depositional sites and a limited time window for preservation of plant–animal interactions. The recognition of pre- and post-depositional trace fossil suites ensures ichnological and ethological fidelity of faunal data on plant–animal interactions.

Revisions to the Eocene carpoflora of Anjou, western France, with new data from X-ray tomography

ABSTRACT Selected fruits and seeds preserved as molds and casts in sediments from the Anjou flora of Maine-et-Loire have been reexamined with the aid of X-ray tomography. Virtual casts and surface renderings from micro-CT scanning data reveal external and internal morphological characters that were not visible by standard reflected light microscopy. Application of this methodology leads to a revision of the fruit formerly treated as Juglandicarya. It is a 5-valved capsule of likely sapindalean affinity, and is placed in Vaudoisia gruetii (Vaudois-Miéja) gen. et. comb. nov. A seed with the characteristic rumination of Anonaspermum is also recognized for the first time, as are capsular fruits of Ericaceae. We note that many disseminules are hidden from optical viewing because they are buried within the hand samples. A more extensive micro-CT scan investigation of more samples, including those showing only fossil leaf impressions at the surface, may be expected to yield a wealth of new information on this classic flora.

Paleobotany of the uppermost Cretaceous Chorrillo Formation, Santa Cruz Province, Argentina: insights in a freshwater floral community

Few latest Cretaceous fossil floras are known for South America, and in particular for the Austral-Magallanes Basin. Recent studies carried out in the Chorrillo Formation (Maastrichtian) revealed a diverse array of fossil elements, including continental invertebrates, vertebrates, palynomorphs, fossil woods and leaf impressions. In this work, we describe the megafloristic elements identified in the unit from two fossiliferous levels, along with a palynological sample obtained from one such level. The first Mesozoic Nymphaeaceae (water lilies) remains for Argentina are reported, consisting of fragmentary leaves and seeds of a minute Nuphar-grade plant. Several leaf impressions referred to dicotiledonean and monocotiledonean morphotypes are also described. Additionally, microscopic remains reveal a diverse palynological assemblage containing terrestrial and aquatic ferns, conifers and angiosperms. A community that inhabited low energy, probably paludal, freshwater environments was identified, based on the sedimentology of the bearing strata such as the presence of hydromorphic paleosols and poorly decomposed organic matter suggesting poor drainage and eventual reducing and anoxic conditions, as well as the presence of Salviniaceae (water ferns), Marsileaceae (water-clovers), Nymphaeaceae and Zygnemataceae (freshwater conjugate algaes). Palynological elements suggest similarities with Campanian to Paleocene Patagonian units, mostly located in the Austral-Magallanes, Cañadón Asfalto and Golfo the San Jorge basins. Finally, aquatic communities from other Maastrichtian units (e.g. La Colonia and Lago Colhué Huapi formations) are compared with the Chorrillo Formation presented herein, suggesting similarities in functional groups even though taxa involved differ partially.

MICROFACIES OF LATE PLEISTOCENE TRAVERTINE DEPOSITS IN JORDAN

The Late Pleistocene travertine outcrops from Deir Alla, Suwayma, and Az Zara were investigated, and their microfacies were identified. The microfacies of the Deir Alla travertines include micrite and spar groundmass, shrubs, crystalline crusts, a stromatolite-like structure, peloids, and cements. Shrub travertine includes spar calcite-coated stems with probably microbial micritic clumps. The crystalline crust travertine displays an alternation of micrite and sparite laminae. The micritic laminae are dark-coloured. Bundles of radial spar crystals are associated locally with micritic groundmass. The crystalline crust developed where biogenic activity is limited. Peloidal microfacies are less than 0.25 mm in diameter, cryptocrystalline, pale-dark green in colour, elliptical to spherical in shape, and usually associated with microorganisms. The microfacies of the Suwayma and Az Zara travertines include crystalline calcite rhombs and other composite scalenohedral crystals. They occur as small anhedral-subhedral crystals, monocrystalline to some polycrystalline, corroded, subrounded, and mainly coated with iron oxide and/or clay minerals. Peloids, ooids, and oncoids are common. They are dark-green coloured, cryptocrystalline to microcrystalline carbonates of spherical and ellipsoidal shape with less than 1 mm in diameter. Rich flora travertines include reed and paper-thin rafts with leaf impressions encrusted on moss cushions. The flora observed in the upper part of the Suwayma section was identified as charophyte oospores (gyrogonites). A few grains of quartz are present as small subhedral-euhedral crystals, monocrystalline, corroded, rounded, and mainly coated with iron oxide. The iron is irregularly distributed among the laminae and voids and is occasionally replaced by carbonates. The described macrophyte encrustation structures probably represent algae, cyanobacteria, or bryophytes. All samples of micrite and spar calcite appear as groundmass.

Coryphoid palms from the K-Pg boundary of central India and their biogeographical implications: Evidence from megafossil remains

Ten palm leaf impressions are documented from the latest Maastrichtian (late Cretaceous) to early Danian (earliest Paleocene) sediments (K-Pg, c. 66–64 Ma) of the Mandla Lobe of the Deccan Inter-trappean Beds, Madhya Pradesh, central India. The palmate leaf shape along with a definite well-preserved costa support their placement in the subfamily Coryphoideae of the family Arecaceae. We place all recovered palm leaf specimens in the fossil genus Sabalites, report seven species of coryphoid palms and describe two new species namely, Sabalities umariaensis sp. nov. and Sabalites ghughuaensis sp. nov. The fossils indicate that coryphoid palms were highly diverse in central India by the latest Cretaceous. These and earlier reported coryphoid palm fossils from the same locality indicate that they experienced a warm and humid tropical environment during the time of deposition. These discoveries confirm the presence of a diversity of Coryphoideae in Gondwana prior to the India-Eurasia collision and provide information about coryphoid biogeographical history over geological time. Based on megafossil remains, we trace coryphoid palm migration pathways from India to mainland Southeast (SE) Asia and other parts of Asia after the docking of the Indian subcontinent with Eurasia early in the Paleogene.

A diverse assemblage of Late Eocene woods from Oregon, western USA

Well-preserved silicified woods from a site near the town of Post, Oregon, western USA, provide insights into the late Eocene vegetation and climate ca. 36 million years and data for comparing with both older and younger wood floras regionally and globally. The composition of this wood flora, taken into consideration along with taxa identified from silicified fruits and seeds of the same locality, provides a more complete picture of the former vegetation. We recognize woods belonging to the families Anacardiaceae (Pistacia terrazasae sp. nov.), Cannabaceae (Celtis popsii sp. nov.), Cercidiphyllaceae (Cercidiphyllum cf. alalongum R.A.Scott et E.A.Wheeler), Fagaceae (Fagus dodgeii sp. nov., Lithocarpoxylon ashwillii sp. nov., Lithocarpoxylon sp., Quercus sp.), Hamamelidaceae (Hamamelidoxylon crystalliferum sp. nov., H. cf. suzukii E.A.Wheeler et T.A.Dillhoff), Juglandaceae (Pterocaryoxylon sp.), Malvaceae (Wataria kvacekii n. sp.), Platanaceae (Platanoxylon cf. haydenii (Felix) Süss et Müll.-Stoll, Platanus sp.), Sapindaceae (Acer, 2 spp.), Trochodendraceae (Trochodendron beckii (Hergert et H.K.Phinney) R.A.Scott et E.A.Wheeler). This assemblage, which we refer to as the Post Hammer flora (UF 279), is comparable in age to the nearby Teater Road flora known mainly from fossil leaf impressions. Comparing the functional traits of the Hammer woods to the older Clarno Nut Beds woods attests to changing climate in the region, including an increase in seasonality.

A Deep Learning Method for Fully Automatic Stomatal Morphometry and Maximal Conductance Estimation.

Stomata are integral to plant performance, enabling the exchange of gases between the atmosphere and the plant. The anatomy of stomata influences conductance properties with the maximal conductance rate, gsmax, calculated from density and size. However, current calculations of stomatal dimensions are performed manually, which are time-consuming and error prone. Here, we show how automated morphometry from leaf impressions can predict a functional property: the anatomical gsmax. A deep learning network was derived to preserve stomatal morphometry via semantic segmentation. This forms part of an automated pipeline to measure stomata traits for the estimation of anatomical gsmax. The proposed pipeline achieves accuracy of 100% for the distinction (wheat vs. poplar) and detection of stomata in both datasets. The automated deep learning-based method gave estimates for gsmax within 3.8 and 1.9% of those values manually calculated from an expert for a wheat and poplar dataset, respectively. Semantic segmentation provides a rapid and repeatable method for the estimation of anatomical gsmax from microscopic images of leaf impressions. This advanced method provides a step toward reducing the bottleneck associated with plant phenotyping approaches and will provide a rapid method to assess gas fluxes in plants based on stomata morphometry.

Fossil leaves of Populus L. (Salicaceae Mirb.) from the upper Pliocene of Tengchong, Yunnan, southwestern China

Fossil leaves of Populus L. (Salicaceae Mirb.) were widely reported in the North Hemisphere during the Cenozoic. However, most of them are leaf impressions without details of cuticles or only preserved as tiny cuticle fragments. Here, we describe several fossil leaves of Populus with fine cuticular structures from the upper Pliocene of Tengchong, western Yunnan, China. The leaves have ovate, rhombic-ovate to orbicular leaf shape with long petioles, pinnate venation, rounded to cuneate bases, acuminate apices and serrate margins. They are pilose bilaterally with multicellular trichome bases and hypostomatic with paracytic stomata. According to the gross morphology and cuticle structures, the present fossils mostly resemble the extant species P. rotundifolia Griff. except that the fossils have denser trichome bases, and are therefore tentatively assigned to Populus cf. rotundifolia Griff. Nowadays, P. rotundifolia is distributed at mountain slopes above an elevation of 2000 m a.s.l. The present new finding indicates that western Yunnan might have approached its present height at least by the late Pliocene. Recent phylogenetic study proposed that the divergence of P. rotundifolia from P. davidiana Dode occurred at the Pleistocene (Calabrian, ca. 0.88 Ma). However, our fossil occurrence implies that such a divergence might have occurred at least by the late Pliocene (3.3–2.8 Ma), much earlier than the molecular estimation. In addition, the Hengduan Mountainous Region might be the species differentiation center of P. rotundifolia from P. davidiana based on their modern distributions and the present fossil occurrence.

Pleistocene plants from Zarzal Formation, middle valley of the Cauca River Basin, Colombia

We report macro and meso palaeobotanical records from the Zarzal Formation, in the Cauca River Depression, and the Quindío-Risaralda Basin between the Western and the Central Cordilleras of Colombia. The fossils correspond to leaves and seeds obtained from layers of mudstones, diatomites, and tuffaceous sandstones deposited in the inter-Andean valleys of Cauca and La Vieja rivers, separated by the Serranía Santa Bárbara ridge between the Valle del Cauca and Quindío departments. The sediments of the Pleistocene Zarzal Formation were deposited in a fluvial-lacustrine environment, with volcanic influence originated in the Central Cordillera to the east of the depositional area. The study here presented allowed the identification of thirteen morphotypes of leaf impressions grouped in six Angiosperm families: Poaceae?/Cyperaceae? and Araceae of the Monocots group, Melastomataceae, Fabaceae and Lauraceae belonging to the Eudicots group and one family of Lycopsida: Thelypteridaceae. On the other hand, very well-preserved silicified micro-seeds were grouped in eight morphotypes, belonging to the botanical groups Cyperaceae and Asteraceae. The fossils found allowed us to identify two types of plant associations that exhibit paleofloristic richness. In the Cauca River Basin, an autochthonous to parautocthonous plant association could correspond to a sub-Andean gallery forest, whilst in the La Vieja River Basin a parautocthonous plant association indicates a swamped floodplain. Keywords: paleoflora, leaves, seeds, Cauca River, La Vieja River, lacustrine deposit.

Dispersed pollen and calyx remains of Diospyros (Ebenaceae) from the middle Miocene “Plant beds” of Søby, Denmark

ABSTRACT Diospyros is a large genus of woody flowering plants with a predominantly subtropical and tropical modern distribution. Fossils attributed to Diospyros are mainly leaf impressions from Cretaceous and Cenozoic strata across the Northern Hemisphere. However, it is difficult to assign such fossils to Diospyros because genus-diagnostic leaf characteristics remain to be identified. Unequivocal fossil records of Diospyros are few, including staminate flowers with in situ pollen from the late Eocene of South Australia and dispersed pollen from Cenozoic strata in the Northern Hemisphere. Here, we investigated dispersed pollen and calyx remains from Miocene deposits of Denmark using a combined scanning electron/light microscopy approach. Tricolporate, relatively large pollen with lalongate pori and long bow-shaped colpi and a distinctive micro/nanorugulate exine ornamentation together with persistent 4-lobed flower calyces allow unambiguous identification of the genus. Based on the large size of the calyx, we describe a new fossil-species of Diospyros. Further, a review of the fossil pollen record of Diospyros shows that, in addition to the Australian record, the genus was present in South China, western North America and Europe during the Eocene and in East and South Africa and Central Asia during the Oligo-Miocene. Although still scanty, the pollen record can contribute vital information for time-calibrated molecular phylogenies to resolve conflicting biogeographic inferences. A thorough description of the historical biogeography of Diospyros is still in its infancy. While we initiate such a study here, development of a comprehensive picture will require further studies of dispersed pollen grains with high taxonomic resolution.

Biotic community and landscape changes around the Eocene–Oligocene transition at Shapaja, Peruvian Amazonia: Regional or global drivers?

Since 2012, we have investigated a stratigraphic section encompassing the late Eocene–earliest Oligocene interval at Shapaja (Tarapoto area, Peruvian Amazonia, ca. 7°S), through paleontological and geological fieldwork. The measured sedimentary series (120 m-thick [West] plus 90 m-thick [East]), assigned to the upper member of the Pozo Formation, records fluvial micro-conglomeratic lenses intercalated with floodplain and evaporite-rich fine red deposits, estuarine/coastal-plain tidally-influenced fine sandstones, and oxbow lake nodule-rich blue clays. This sedimentary shift coincides locally with the demise of the large Eocene coastal-plain wetland known as Pozo System. The late Eocene–early Oligocene Shapaja section was extensively sampled for chemostratigraphy (δ 13 C on dispersed organic matter and pedogenic carbonate nodules), which in turn allowed for refining the location of the Eocene-Oligocene Transition (EOT) and other climatic events recognized at a global scale (i.e., Oi-1 and Oi-1a). The section has yielded nine fossil localities with plant remains (leaves, wood, charophytes, and palynomorphs), mollusks, decapods, and/or vertebrates (selachians, actinopterygians, lungfishes, amphibians, sauropsids, and mammals), documenting ~130 distinct taxa. Four localities of the upper member of the Pozo Formation at Shapaja predate the EOT, one is clearly within the EOT, while four are earliest/early Oligocene in age. The small leaf impressions found along the Shapaja section could be indicative of dry and/or seasonal conditions for this region throughout and after the EOT. Monkeys, indicative of tropical rainforest environments, are only recorded in a latest Eocene locality (TAR-21). Two biotic turnovers are perceptible in the selachian, metatherian, and rodent communities, well before the EOT [~35–36 Ma] and a few hundred thousand years after the EOT [~33 Ma]. The latter turnover seems to be primarily related to a global sea-level drop (ichthyofauna: marine-littoral elements replaced by obligate freshwater taxa) and/or the onset of a drier and more seasonal climate in early Oligocene times (terrestrial components). Changes in the structure of the Shapaja paleocommunities were mostly driven by the flexural subsidence during the late Eocene, and then globally driven by the earliest Oligocene climatic deterioration. • The Shapaja section spans the late Eocene–early Oligocene interval ( ca. 36–32.5 Ma). • Micro- and macroremains of 129 plant and animal fossil taxa were recognized. • Two faunal turnovers are recorded on both sides of the Eocene-Oligocene transition. • Shapaja records the earliest occurrence of South American primates and sloth. • Community changes are locally- then globally-driven (late Eocene/earliest Oligocene).

Record of plant fossils from freshly discovered succession of the Pariwar Formation, Jaisalmer Basin, western India

ABSTRACT This research paper underscores the systematic study of the two species Ptilophyllum cutchense (Morris) Bose and Kasat and Ptilophyllum acutifolium (Morris) Bose and Kasat of the genus Ptilophyllum Morris. These species of the bennettitalean flora have been recorded for the first time from a newly discovered fossiliferous sedimentary succession of the Pariwar Formation cropping out near Serawa Village located at about 2 km west of Sanu Village of the Jaisalmer Basin. The investigated Serawa Section entails extremely rich record of undiversified bennettitalean flora. The Ptilophyllum cutchense of this studied succession also presents its first record from the Pariwar Formation of the Jaisalmer Basin. Ribbed axes are also described in this section. The floral record from the exposure near Serawa Village has been found somewhat different from the floral records made by earlier workers from the other known localities of the Pariwar Formation. The presence of leaf impressions, calcareous nannofossils and bioturbations in the successive horizons of the studied succession indicates the presence of shallow marine condition at the time of deposition of the rock unit under present endeavour.

Paleocene high-latitude leaf flora of Antarctica Part 1: entire-margined angiosperms

Paleocene leaf floras are rare in high latitudes of the Southern Hemisphere, where studies have shown higher taxonomic diversity compared to Northern Hemisphere equivalents. The floras provide valuable insights into biodiversity and forest communities during the Paleocene. The Antarctic Peninsula hosts a wealth of Paleocene–Eocene floras which have been used to interpret climates before, during and after one of the most abrupt and transient warming events known from the geological record. The best-preserved and most diverse Paleocene macrofossils from this region come from the Cross Valley Formation, Seymour Island Group, which have previously provided evidence for warm temperate climates prior to the PETM. Here we present the taxonomy of leaf impressions from the Paleocene Cross Valley Flora for one species and ten new leaf morphotypes of entire-margined angiosperms. The new morphotypes provide evidence of an increased angiosperm diversity within cool-temperate Gondwanan forest inhabiting the east side of the Antarctic Peninsula, which contrasts with a lower floral diversity on the west side of the Peninsula during the late Paleocene.

A new Oligocene fern of Dryopteridaceae from the České středohoří Mts (Czech Republic)

A new palaeobotanical site was recovered at artificial excavations within the city district of Ústí nad Labem called Mojžíř in northern Bohemia (Czech Republic) that yielded slabs of Oligocene tephritic pyroclastic rocks with plant impressions. The fossiliferous layer belongs to the Děčín Formation of the České středohoří Mts. dated to the Oligocene (30.8–24.7 Ma). One of the recovered fossils belongs to a new leptosporangiate fern matching modern representatives of Polystichum Roth (Dryopteridaceae Herter). These frond fragments are partly fertile and allow studying the position of sori and details of indusia and spores. This fossil fern is described here as a new species of Polystichum, P. pacltovae Kvaček sp. nov., which matches the modern European species of Polystichum, namely Polystichum braunii (Spenner) Fée . Accompanying plant fossils include another fern frond described as "Aspidium "elongatum Heer (non Swartz) of unknown affinities, fragmentary needles assigned to Pinus cf. hepios (Unger) Unger of the Pinaceae and leaf impressions of Betulaceae comparable to Betula brongniartii Ettingshausen.

Machine Learning Enables High-Throughput Phenotyping for Analyses of the Genetic Architecture of Bulliform Cell Patterning in Maize.

Bulliform cells comprise specialized cell types that develop on the adaxial (upper) surface of grass leaves, and are patterned to form linear rows along the proximodistal axis of the adult leaf blade. Bulliform cell patterning affects leaf angle and is presumed to function during leaf rolling, thereby reducing water loss during temperature extremes and drought. In this study, epidermal leaf impressions were collected from a genetically and anatomically diverse population of maize inbred lines. Subsequently, convolutional neural networks were employed to measure microscopic, bulliform cell-patterning phenotypes in high-throughput. A genome-wide association study, combined with RNAseq analyses of the bulliform cell ontogenic zone, identified candidate regulatory genes affecting bulliform cell column number and cell width. This study is the first to combine machine learning approaches, transcriptomics, and genomics to study bulliform cell patterning, and the first to utilize natural variation to investigate the genetic architecture of this microscopic trait. In addition, this study provides insight toward the improvement of macroscopic traits such as drought resistance and plant architecture in an agronomically important crop plant.