A new remarkable Early Cretaceous nelumbonaceous fossil bridges the gap between herbaceous aquatic and woody protealeans.

Dating back to the late Early Cretaceous, the macrofossil record of the iconic lotus family (Nelumbonaceae) is one of the oldest of flowering plants and suggests that their unmistakable leaves and nutlets embedded in large pitted receptacular fruits evolved relatively little in the 100 million years since their first known appearance. Here we describe a new fossil from the late Barremian/Aptian Crato Formation flora (NE Brazil) with both vegetative and reproductive structures, Notocyamus hydrophobus gen. nov. et sp. nov., which is now the oldest and most complete fossil record of Nelumbonaceae. In addition, it displays a unique mosaic of ancestral and derived macro- and micromorphological traits that has never been documented before in this family. This new Brazilian fossil-species also provides a rare illustration of the potential morphological and anatomical transitions experienced by Nelumbonaceae prior to a long period of relative stasis. Its potential plesiomorphic and apomorphic features shared with Proteaceae and Platanaceae not only fill a major morphological gap within Proteales but also provide new support for their unexpected relationships first suggested by molecular phylogenies.

An integrated leaf trait analysis of two Paleogene leaf floras.

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.

Traces of calcium oxalate biomineralization in fossil leaves from late Oligocene maar deposits from Germany.

Calcium oxalate (CaOx) is one of the most common bio-mineral in extant plants and is believed to serve a variety of functions such as calcium storage and herbivore defense. However, traces of CaOx crystals have rarely been identified in fossil plants, and they are primarily known from fossil gymnosperms, where empty cavities of former CaOx crystals or ghost crystals have been reported from leaf cuticles of some Late Cretaceous and Cenozoic conifers. Here we investigate fossil angiosperm leaves from the late Oligocene Rott Fossil Lagerstätte and report ghost crystals of various shapes, sizes and topology (distribution patterns), and cavities. These micromorphological structures of fossil leaves are compared to CaOx deposits in leaves of extant plants: globular structures in fossil leaves resemble CaOx druses (crystal aggregates) in fresh leaves in size and distribution; and angular or brick-shaped structures in the vascular system of fossil leaves closely resemble prismatic CaOx crystals in the vascular system of extant leaves in both size and topology. Chemically, CaOx druses have survived fossilization as cavities only, and were replaced by organic matter and ghost minerals containing Ca, Si, Al, S, and Fe. The identification of former CaOx remains in leaf fossils provides novel insights on the fate of plant bio-minerals during fossilization. More importantly, it provides an additional aspect of the ecophysiology of fossil plants thus improving the accuracy of palaeoecological reconstructions and can provide a broader perspective on the evolution of CaOx and their rule in plant ecology across geological timescales. Alternative interpretations of the fossil microstructures are discussed but ruled out.

First evidence of ranunculids in Early Cretaceous tropics.

Early Cretaceous floras containing angiosperms were described from several geographic areas, nearly from the Arctic to the Antarctic, and are crucial to understand their evolution and radiation. However, most of these records come from northern mid-latitudes whereas those of lower paleolatitude areas, such as the Crato Fossil Lagerstätte in NE Brazil, are less studied. Here, we describe from this region of northern Gondwanan origin, two fossil-species of eudicots belonging to a new extinct genus Santaniella gen. nov. Together with several vegetative axes and leaves, anatomically well-preserved fruits with seeds and persistent perianth-like organs allowed us to reconstruct its potential affinities with ranunculids, and presumably Ranunculaceae. Previous records putatively assigned to Ranunculales are all from mid-latitudes, and their first unequivocal occurrence in a low-latitude area supports further the hypothesis of a widespread radiation of the earliest diverging eudicot lineage by this early age.

Reconstructing leaf area from fragments: testing three methods using a fossil paleogene species.

PREMISE: Fossil leaf traits can enable reconstruction of ancient environments and climates. Among these, leaf size has been particularly studied because it reflects several climatic forcings (e.g., precipitation and surface temperature) and, potentially, environment characteristics (e.g., nutrient availability, local topography, and openness of vegetation). However, imperfect preservation and fragmentation can corrupt its utilization. We provide improved methodology to estimate leaf size from fossil fragments. METHODS: We apply three methods: (1) visually reconstructing leaf area based on taxon-specific gross morphology; (2) estimating intact leaf area from vein density based on a vein scaling relationship; and (3) a novel complementary method, determining intact leaf length based on the tapering of the midvein in the fragment. We test the three methods for fossils of extinct Eotrigonobalanus furcinervis (Fagaceae) from two lignite horizons of the middle and late Eocene of central Germany respectively (~45/46 and 35/36 Ma). RESULTS: The three methods, including the new one, yield consistent leaf size reconstructions. The vein scaling method showed a shift to larger leaf size, from the middle to the late Eocene. CONCLUSIONS: These methods constitute a toolbox with different solutions to reconstruct leaf size from fossil fragments depending on fossil preservation. Fossil leaf size reconstruction has great potential to improve physiognomy-based paleoenvironmental reconstructions and the interpretation of the fossil record.

Revealing the diversity of amber source plants from the Early Cretaceous Crato Formation, Brazil.

BACKGROUND: Amber has been reported from the Early Cretaceous Crato Formation, as isolated clasts or within plant tissues. Undescribed cones of uncertain gymnosperm affinity have also been recovered with amber preserved in situ. Here, we provide multiple lines of evidence to determine the botanical affinity of this enigmatic, conspicuous cone type, and to better understand the diversity of amber-source plants present in the Crato Formation and beyond. RESULTS: A new taxon of amber-bearing pollen cone Araripestrobus resinosus gen. nov. et sp. nov. is described here from complete cones and characteristic disarticulated portions. The best-preserved cone portion has both in situ amber infilling the resin canals inside the preserved microsporophyll tissues and pollen of the Eucommiidites-type. This places this genus within the Erdtmanithecales, an incompletely known gymnosperm group from the Mesozoic. FTIR analysis of the in situ amber indicates a potential araucariacean conifer affinity, although affinity with cupressacean conifers cannot be definitely ruled out. Pyr-GC-MS analysis of the Araripestrobus resinosus gen. nov. et sp. nov. in situ fossil resin shows that it is a mature class Ib amber, thought to indicate affinities with araucariacean and cupressacean, but not pinaceous, conifers. This is the first confirmed occurrence of this class of amber in the Crato Formation flora and in South America, except for an archaeological sample from Laguna Guatavita, Colombia. CONCLUSIONS: The combined results of the cones' novel gross morphology and the analyses of the in situ amber and pollen clearly indicate that the new taxon of resinous gymnosperm pollen cones from the Crato Formation is affiliated with Erdtmanithecales. The cone morphology is very distinct from all known pollen cone types of this extinct plant group. We therefore assume that the plant group that produced Eucommiidites-type pollen is much more diverse in habits than previously thought. Moreover, the diversity of potential amber source plants from the Crato Formation is now expanded beyond the Araucariaceae and the Cheirolepidiaceae to include this member of the Erdtmanithecales. Despite dispersed Eucommiidites pollen being noted from the Crato Formation, this is the first time macrofossils of Erdtmanithecales have been recognized from the Early Cretaceous of South America.

Plant-insect interactions patterns in three European paleoforests of the late-Neogene-early-Quaternary.

Plants and insects are constantly interacting in complex ways through forest communities since hundreds of millions of years. Those interactions are often related to variations in the climate. Climate change, due to human activities, may have disturbed these relationships in modern ecosystems. Fossil leaf assemblages are thus good opportunities to survey responses of plant-insect interactions to climate variations over the time. The goal of this study is to discuss the possible causes of the differences of plant-insect interactions' patterns in European paleoforests from the Neogene-Quaternary transition. This was accomplished through three fossil leaf assemblages: Willershausen, Berga (both from the late Neogene of Germany) and Bernasso (from the early Quaternary of France). In Willershausen it has been measured that half of the leaves presented insect interactions, 35% of the fossil leaves were impacted by insects in Bernasso and only 25% in Berga. The largest proportion of these interactions in Bernasso were categorized as specialist (mainly due to galling) while in Willershausen and Berga those ones were significantly more generalist. Contrary to previous studies, this study did not support the hypothesis that the mean annual precipitation and temperature were the main factors that impacted the different plant-insect interactions' patterns. However, for the first time, our results tend to support that the hydric seasonality and the mean temperature of the coolest months could be potential factors influencing fossil plant-insect interactions.