Diverse Plant Assemblages Research Articles

Reinvestigating the fossil leaf Welwitschiophyllum brasiliense Dilcher et al. (2005), from the Lower Cretaceous Crato Formation of Brazil

The Lower Cretaceous Crato Formation of north-east Brazil yields a diverse plant assemblage. It has yielded many macrofossils thought to be related to the enigmatic gymnosperm group Gnetales, including the long leaf Welwitschiophyllum brasiliense Dilcher et al. 2005. This fossil plant is considered to be related to the extant gnetalean Welwitschia mirabilis Hooker 1863, despite lacking many gnetalean characteristics. Presently, this macrophyte fossil is known only from detached leaves and much anatomical information is currently unavailable. The reproductive structures assigned to the family Welwitschiaceae in the Crato Formation, as well as several key morphological features of the leaves are currently thought to relate fossil Welwitschiophyllum to extant Welwitschia. These leaf characters include: isobilateral leaf form, triangular elongated leaf shape with a wide base, longitudinal splitting from a frayed leaf apex, numerous parallel veins and possible thickening of the epidermis. However, several of these leaf characteristics also occur in many other macrophytes, perhaps as a result of convergence. Anatomical and morphological data described here from fossil Welwitschiophyllum leaves is compared with extant Welwitschia. Our results show that Welwitschiophyllum can only be placed tentatively in Gnetales, as many of the features we report are not diagnostic, and may have resulted from convergent evolution (e.g., gum). Fossils with better anatomical preservation and the reconstruction of the whole plant are really needed to better understand the affinities of Welwitschiophyllum.

Land use history drives differences in functional composition and losses in functional diversity and stability of Neotropical urban forests

With urbanisation rapidly transforming our world, a better understanding of how urban ecosystems can contribute to biodiversity conservation is urgently needed. Here, we investigated the functional composition and diversity of plant assemblages in different types of urban forests with the intent to predict the stability of the functions provided by these forests through the functional redundancy and response diversity of species. For this, we used data from non-urban mature forests, remnant urban forests, urban forests regenerated from croplands and urban forests regenerated from soil denudation, all located in the Brazilian Atlantic Forest. Our results showed that species functional composition shifted among urban and non-urban forests. However, functional diversity was lost only in urban forests with some previous use, indicating that the natural regeneration of urban forests after previous land use results in functionally poor forests. Urban forests regenerated from soil denudation (more intense disturbance) had a lower functional diversity. Conversely, urban forests regenerated from cropland (less intense disturbance) showed only a reduction in the number of functions provided. Our analysis also revealed the reduced functional redundancy and response diversity of urban forests with previous land use, which may indicate a greater vulnerability of the functions provided by these forests. Thus, we emphasise in this study the importance of land use history for decision making in urban forest conservation policies and highlight the crucial role of natural remnant urban forests as reservoirs of functional diversity and stability in highly degraded and fragmented landscapes.

Species-specific effects of passive warming in an Antarctic moss system.

Polar systems are experiencing rapid climate change and the high sensitivity of these Arctic and Antarctic ecosystems make them especially vulnerable to accelerated ecological transformation. In Antarctica, warming results in a mosaic of ice-free terrestrial habitats dominated by a diverse assemblage of cryptogamic plants (i.e. mosses and lichens). Although these plants provide key habitat for a wide array of microorganisms and invertebrates, we have little understanding of the interaction between trophic levels in this terrestrial ecosystem and whether there are functional effects of plant species on higher trophic levels that may alter with warming. Here, we used open top chambers on Fildes Peninsula, King George Island, Antarctica, to examine the effects of passive warming and moss species on the abiotic environment and ultimately on higher trophic levels. For the dominant mosses, Polytrichastrum alpinum and Sanionia georgicouncinata, we found species-specific effects on the abiotic environment, including moss canopy temperature and soil moisture. In addition, we found distinct shifts in sexual expression in P. alpinum plants under warming compared to mosses without warming, and invertebrate communities in this moss species were strongly correlated with plant reproduction. Mosses under warming had substantially larger total invertebrate communities, and some invertebrate taxa were influenced differentially by moss species. However, warmed moss plants showed lower fungal biomass than control moss plants, and fungal biomass differed between moss species. Our results indicate that continued warming may impact the reproductive output of Antarctic moss species, potentially altering terrestrial ecosystems dynamics from the bottom up. Understanding these effects requires clarifying the foundational, mechanistic role that individual plant species play in mediating complex interactions in Antarctica's terrestrial food webs.

Large‐scale α‐diversity patterns in plants and ground beetles (Coleoptera: Carabidae) indicate a high biodiversity conservation value of China's restored temperate forest landscapes

AbstractAimFollowing the near‐complete destruction of China's forest ecosystems during the 20th century, recent reforestation programmes have created large‐scale mosaics of protected secondary and plantation forests. These restored forests are often assumed to have limited biodiversity conservation value, but large‐scale evaluations of their diversity are lacking. In our study, we compared α‐diversity and species dissimilarity patterns of vascular plants and ground beetles (Coleoptera: Carabidae) in restored secondary and plantation forests to remnant mature forests across north‐eastern temperate China. We also assessed functional traits of beetles and cross‐taxon diversity links to evaluate differences in ecosystem functioning among forest types.Location. Northeast China.MethodsVascular plant and ground beetle assemblages were recorded in 159 temperate forest plots. The α‐diversity and species compositional dissimilarity of these taxa and the functional traits of beetles were compared between plantation, secondary and mature forest ecosystems.ResultsHerbaceous plant species richness peaked in mature forests, while carabid and woody plant diversity did not differ between forest types. Species dissimilarity of carabids was lowest in mature forests and highest in plantation forests. Mature forest contained the highest proportion of carnivorous beetles and secondary forests of large‐bodied carabids. Carabid diversity and woody plant species richness were positively correlated in mature forests, but not in secondary or plantation forests.Main conclusionsWhile China's mature forests show a great conservation value in harbouring highly diverse herbaceous plant assemblages and an abundance of distinct invertebrate trait groups such as small predatory carabids, China's restored temperate forests also support a high diversity of woody plants and carabids. Overall, our findings offer an encouraging conservation message for biodiversity conservation in China and demonstrate the importance of policy measures that ensure effective long‐term protection of both, China's remnant mature forests, but also its new forest ecosystems.

Functional diversity and composition of Caatinga woody flora are negatively impacted by chronic anthropogenic disturbance

Abstract Tropical plant assemblages can be taxonomically and phylogenetically impoverished by chronic anthropogenic disturbance (CAD), such as firewood collection and extensive grazing. However, to what extent the functional dimension responds to CAD is still unclear. Such knowledge is urgently required for predicting, preventing or even reversing the impacts of CAD. Chronic anthropogenic disturbance may operate as an ecological filter by selecting functional trait values (e.g. low wood density), thereby altering the functional composition and diversity of plant assemblages. We tested this hypothesis using 29 woody plant assemblages across three ontogenetic stages (seedlings, saplings and adults) in a 220‐km2 landscape of the Caatinga, northeast Brazil. We adopted a CAD index consisting of four indicators (proximity to urban centre and houses and the density of both people and livestock) and tested how well it explained the functional diversity and effect sizes (richness, evenness and dispersion) and composition (community‐weighted mean). Chronic anthropogenic disturbance affected several functional metrics across the three ontogenetic stages. However, CAD effects were stronger in adult communities by negatively affecting functional richness, dispersion and their effect sizes. CAD also altered the functional composition of leaf mass per area, woody density and leaf area of adult assemblages. Sapling communities were affected in terms of functional composition (leaf area, leaf dry matter and wood density), with positive and negative effects, while seedling assemblages responded positively to CAD only in terms of functional evenness and its effect size. Some changes in functional metrics were influenced by dominant Euphorbiaceae species across ontogenetic stages, especially in terms of leaf area and woody density. Synthesis. Chronic anthropogenic disturbance is an important driver of plant‐community functional organization across ontogenetic stages in the Caatinga. Adult assemblages are particularly sensitive and tend to lose functional niche space and support more acquisitive rather than conservative strategies as chronic anthropogenic disturbance increases. The proliferation of Euphorbiaceae disturbance‐adapted species can explain part of the community responses to chronic anthropogenic disturbance. Our findings highlight the ecological effects of chronic anthropogenic disturbance and show that it is a key influence on tropical biotas. Changes in plant functional traits associated with plant resource use are likely to affect ecosystem functioning and services provided by Caatinga.

Rinistachya hilleri gen. et sp. nov. (Sphenophyllales), from the upper Devonian of South Africa

A rich and diverse plant assemblage has been excavated from latest Devonian (Famennian) black shales of the Witpoort Formation (Witteberg Group) at Waterloo Farm, close to the city of Grahamstown (South Africa). Several specimens of a new sphenopsid have been collected. The description of this as a new taxon, here named Rinistachya hilleri, gen. et sp. nov., provides an important addition to the scarce early record of the group. Rinistachya hilleri presents a novel architecture that include apparently plesiomorphic characters, reminiscent of the organisation of the Iridopteridales (including the production of two types of laterals at one node, the location of fertile parts in loose whorls on lateral branches and an organisation of the fertile parts in which they branch several times before bearing distally elongate sporangia). Other characters unambiguously nest Rinistachya within the Sphenopsida (including presence of planate and slightly webbed ultimate appendages and lateral strobili made of successive whorls of fertile leaves with fertile parts located at their axil). This provides strong support for a close relationship between Sphenopsida and Iridopteridales. Rinistachya furthermore represents the first record of a Devonian sphenopsid from Gondwana and extends the known distribution of the Sphenopsida from the tropics to very high palaeolatitudes. It is a new sphenopsid with a peculiar organisation. The new taxon allows better characterization of the initial evolutionary radiation at the base of the group.

Spontaneous revegetation of a peatland in Manitoba after peat extraction: diversity of plant assemblages and restoration perspectives

There are very few studies on the spontaneous revegetation of cutover fens or bogs from which peat has been extracted to the minerotrophic layers. Most peatlands with fen-type residual peat have problems regenerating a plant cover satisfactorily from a restoration point of view. We nevertheless found a site (Moss Spur, Manitoba, Canada) presenting a substantial and diversified spontaneous plant cover. We estimated that the site would provide insights about natural revegetation processes operating in peatlands. Vegetation assemblages and environmental conditions were surveyed 19 years after extraction activities ceased. Moss Spur has densely revegetated (163 plant species, vegetation cover of 94%) with minimal human assistance. However, the composition of plant assemblages varies considerably across the site, depending on certain abiotic variables, particularly water pH, water table level, and the thickness of the residual peat layer. Moss Spur was remarkably wet considering the past peat extraction activities and the absence of active rewetting procedures. The high water table level may in part explain the successful revegetation. However, plant assemblages were not of equal quality from a restoration perspective. Some assemblages were highly diversified, and especially those dominated by Scirpus cyperinus, a species that should be further considered in peatland restoration projects to direct the recovery of the peatland towards a natural fen species composition.

Soil C:N:P stoichiometry responds to vegetation change from grassland to woodland

Woody encroachment has been a major land cover change in dryland ecosystems during the past century. While numerous studies have demonstrated strong effects of woody encroachment on soil carbon (C), nitrogen (N), and phosphorus (P) storage, far less is known about the plasticity of soil C:N:P stoichiometry in response to woody encroachment. We assessed landscape-scale patterns of spatial heterogeneity in soil C:N:P ratios throughout a 1.2 m soil profile in a region where grassland is being replaced by a diverse assemblage of subtropical woody plants dominated by Prosopis glandulosa, an N2-fixing tree. Woody species had leaf and fine root C:N:P ratios significantly different from grasses. Variation in soil C:N ratios in both horizontal and vertical planes was remarkably smaller than that of soil N:P and C:P ratios. Spatial patterns of soil C:N ratio throughout the profile were not strongly related to vegetation cover. In contrast, spatial patterns of soil N:P and C:P ratios displayed a strong resemblance to that of vegetation cover throughout the soil profile. Within the uppermost soil layer (0–5 cm), soil N:P and C:P ratios were higher underneath woody patches while lower within the grassland; however, this pattern was reversed in subsurface soils (15–120 cm). These results indicate a complex response of soil C:N:P stoichiometry to vegetation change, which could have important implications for understanding C, N, and P interactions and nutrient limitations in dryland ecosystems.

Response of plant diversity to moss, Carex or Scirpus revegetation strategies of wet depressions in restored fens

Pool margins and wet depressions (hollows) contribute considerably to peatland biodiversity by sheltering specific plant assemblages. In peatlands restored after peat extraction, the typical communities associated with pools generally fail to re-establish if only the moss layer transfer technique is applied, a common approach on flat bare peatlands. To adapt peatland ecological restoration methods for recolonizing shallow wet fen habitats, this study investigates the response of plant communities re-establishing in wet depressions subjected to four revegetation strategies. In a restored fen (southeastern Quebec, Canada), 48 depressions were dug out and revegetated with 1) mosses, 2) Carex species, 3) Scirpus validus, or 4) through spontaneous colonization (control treatment without implanted species). After four growing seasons, plant community structure and composition were surveyed in and outside the revegetated area respectively to test whether reintroduced communities had a propensity to extend beyond the central wet depression. Restoration strategies strongly impacted plant communities. Moss-revegetated wet depressions had higher moss and vascular fen-specialist species richness and distinct species assemblages relative to other treatments. Carex treatment increased only vascular cover compared to control, while Scirpus validus treatment did not differ from control. The positive impact of moss transfer was local and limited to core revegetated areas, as transferred plant material did not colonize any further. Our results suggest that transferring moss in created wet depressions is an effective strategy to foster the recolonization of diverse and distinct plant assemblages, and thereby restore local fen biodiversity hotspots.

Araucaria bract-scale complex and associated foliage from the early-middle Eocene of Antarctica and their implications for Gondwanan biogeography

ABSTRACTThe early-middle Eocene Fossil Hill flora from King George Island in the Antarctic Peninsula regions is one of the most diverse Cenozoic plant assemblages in Antarctica. It represents a rich Nothofagus and conifer dominated vegetation. These plant fossils, especially conifers are of crucial importance for understanding the biogeographic history of the Gondwanan plants. Here we describe the first Araucaria bract-scale complex, A. fildesensis sp. nov., and associated foliage from the Fossil Hill flora and tentatively assigned them to the Section Eutacta, which is today restricted to Australasia, based on comparison with extant material. This study confirms that Araucaria species with small bract-scale complexes, small scale-like mature leaves and awl-shaped juvenile leaves like those of extant Section Eutacta, lived in Antarctica in the Eocene. These fossils provide potential evidence for the trans-Antarctic floristic changes of Araucaria species in the Section Eutacta between southern Australia and southern South America during the Eocene, when Antarctica was ice-free and forested.

Surprisingly modern Latest Cretaceous– earliest Paleocene woods of India

ABSTRACT Background and approach – The Deccan Intertrappean Beds of Central India contain a diverse assemblage of fossil plants, including petrified woods from 15 localities. These beds are dated at c. 67–64 Ma, i.e. latest Cretaceous–earliest Paleocene and span the K-Pg boundary, a significant time in angiosperm history. At this time, the Indian tectonic plate was halfway on its journey from Gondwana to its collision with Asia, and relatively close to the equator. We provide descriptions in IAWA Hardwood List codes for 47 species of Deccan fossil woods, based on our examination of thin sections of these woods, mostly holotypes that are housed at the Birbal Sahni Institute of Palaeobotany, Lucknow, India. An appendix lists all validly published Deccan wood species of which we are aware, including 52 that we were not able to examine. Main results – The Deccan fossil woods described herein include the oldest known occurrences of some orders, families or genera viz. Lamiales (Lamia-ceae), Achariaceae (Hydnocarpus-like wood), Anacardiaceae, Simaroubaceae (Ailanthus-like and Simarouba-like woods), subfamily Leeoideae (Vitaceae), subfamily Myrtoideae (Myrtaceae), subfamily Planchoideae (Lecythidaceae), tribe Castilleae (Moraceae), tribes Grewioideae and Sterculioideae (Malvaceae). These first fossil records are discussed with reference to other macrofossil and pollen records of the same or related clades. They complement recent work on the oldest known Olea and Connaraceae also documented by Deccan woods.For the Deccan woods we examined, we could confirm the earlier taxonomic assignment at least down to order or family level for 29 taxa. Ordinal level affinities are ambiguous for eight of the taxa. In two cases, we revised the taxonomic assignment to other families; for another eight, the original assignment was found to be incorrect, but we are unable to suggest alternative affinities. Evolutionary implications – Only 3% of all Deccan woods have scalariform perforations and the incidences of so-called specialized features in the Baileyan sense are high, so these woods have a remarkably “modern” aspect. This is anomalous in comparison with contemporaneous fossil woods from higher paleolatitudes, and seemingly they are more “derived” than the recent flora. In these respects, the Deccan woods constitute a unique assemblage. The low incidence of scalariform perforations suggests xeric conditions, while – in contrast – the low incidence of distinct growth ring boundaries suggests an aseasonal everwet climate. It is speculated that convergent xylem specialization, especially the selection for simple perforations, was enhanced by the climatic conditions found at low paleolatitudes with high temperatures as would characterize the Deccan Intertrappean Beds at the K-Pg boundary.

The Piedra Chamana fossil woods (Eocene, Peru)

The fossil woods and leaves of the Fossil Forest Piedra Chamana represent a diverse assemblage of plants dating to 39 Ma (late Middle Eocene). The fossils are preserved in an ashfall and overlying lahar deposits near the small village of Sexi in the northern Peruvian Andes (central Cajamarca). The assemblage includes dicot wood types and leaf morphotypes, as well as a diversity of monocot material. The ~30 dicot wood types are referred to the families Acanthaceae, Anacardiaceae, Apocynaceae, Combretaceae, Cordiaceae, Dipterocarpaceae, Euphorbiaceae, Fabaceae, Lechythidaceae, Lythraceae, Malvaceae, Melastomataceae, Muntingiaceae, Rubiaceae, Rutaceae, and Sapindaceae. Described herein are descriptions of the first 17 wood types that have been assigned to the families Acanthaceae through Lythraceae; descriptions of the additional wood types will appear in a later paper. The paleovegetation can be characterized as lowland tropical forest with a dry aspect based on preliminary analysis of floristic affinities and wood anatomical characteristics of the fossils.

Fantastic Wetlands and Where to Find Them: Modeling Rich Fen Distribution in New York State with Maxent

Rich fens are groundwater dependent, mineral-rich wetlands that support diverse plant assemblages and high densities of rare species. Despite their conservation importance, fens are threatened by habitat loss, altered nutrient regimes, invasive species, and groundwater extraction. Fen conservation is hindered by limited inventory efforts. We used maximum entropy modeling (maxent) to estimate fen distribution throughout New York State (NYS), USA (125,936 sq. km). During predictor assembly, coarse-resolution climate variables (temperature, humidity, and precipitation) were statistically downscaled to match higher-resolution terrain variables (10 m2) for fen distribution modeling using linear regression for temperature and humidity variables (R2 = 0.92), and thin-plate spline regression for precipitation (mean absolute error = 10.14 mm). A nine-parameter maxent model of fen distribution incorporating geological characteristics, soils, landcover, climate (PC axis 1), terrain facets, and hydrology accurately predicted fen records (AUC = 0.97), with an 82% correct classification rate compared to 70% for a null model. Fen habitat spanned only 0.04% of NYS, and matched well with assertions that fens occupy narrowly-distributed, rare hydrogeologic settings. Our results suggest distribution modeling techniques may improve fen detection in large, poorly sampled regions.

Links between plant and fungal diversity in habitat fragments of coastal shrubland.

Habitat fragmentation is widespread across ecosystems, detrimentally affecting biodiversity. Although most habitat fragmentation studies have been conducted on macroscopic organisms, microbial communities and fungal processes may also be threatened by fragmentation. This study investigated whether fragmentation, and the effects of fragmentation on plants, altered fungal diversity and function within a fragmented shrubland in southern California. Using fluorimetric techniques, we assayed enzymes from plant litter collected from fragments of varying sizes to investigate enzymatic responses to fragmentation. To isolate the effects of plant richness from those of fragment size on fungi, we deployed litter bags containing different levels of plant litter diversity into the largest fragment and incubated in the field for one year. Following field incubation, we determined litter mass loss and conducted molecular analyses of fungal communities. We found that leaf-litter enzyme activity declined in smaller habitat fragments with less diverse vegetation. Moreover, we detected greater litter mass loss in litter bags containing more diverse plant litter. Additionally, bags with greater plant litter diversity harbored greater numbers of fungal taxa. These findings suggest that both plant litter resources and fungal function may be affected by habitat fragmentation’s constraints on plants, possibly because plant species differ chemically, and may thus decompose at different rates. Diverse plant assemblages may produce a greater variety of litter resources and provide more ecological niche space, which may support greater numbers of fungal taxa. Thus, reduced plant diversity may constrain both fungal taxa richness and decomposition in fragmented coastal shrublands. Altogether, our findings provide evidence that even fungi may be affected by human-driven habitat fragmentation via direct effects of fragmentation on plants. Our findings underscore the importance of restoring diverse vegetation communities within larger coastal sage scrub fragments and suggest that this may be an effective way to improve the functional capacity of degraded sites.

Reconstructing diagenetic conditions of bone at the Gray Fossil Site, Tennessee, USA

The preservation of vertebrate fossils requires transformation of the original bioapatite mineral matrix, predominantly hydroxylapatite, during diagenesis into a thermodynamically more stable phase. Fossil bone geochemistry and structure provides a wealth of information on the conditions present during diagenesis, including site redox and pH, and about sedimentation rates during burial. The Gray Fossil Site preserves Late Neogene lacustrine deposits that serve as one of a few records of North American paleoclimate during a critical period of the Cenozoic. Despite having >40 vertebrate species and diverse plant assemblages, none of the prior studies used bone composition to understand what paleoenvironmental and diagenetic conditions must have been like to facilitate bone preservation and fossilization. Alligator sp. phalanges were examined using multiple geochemical tools, including Fourier-transform infrared spectroscopy, X-ray diffraction, and electron microprobe analyses. Evidence of bioerosion within thin cortical and isolated trabecular regions of bone suggests biotic utilization of organics (collagen) and/or the mineral(s) following deposition. Chemically zoned and laminated cortical Alligator bone is interpreted as preserved lines of arrested growth that developed during life, and supports previous interpretations of a regional seasonal climate. Lastly, the Alligator bones are mineralogically heterogeneous as fluorinated and iron-containing apatite phases. Compared to modern bone, iron concentrations were high, at up to 3wt%. The uptake of Fe by the Alligator bones examined in this study suggests that fluids present during diagenesis that led to bone preservation within the lacustrine sediment at the Gray Fossil Site were likely acidic, anoxic, and reducing.

Influence of plant resistance traits in selectiveness and species strength in a tropical plant-herbivore network.

Plant-herbivore networks are highly specialized in their interactions, yet they are highly variable with regard to the relative importance of specific host species for herbivores. How host species traits determine specialization and species strength in this antagonistic network is still an unanswered question that we addressed in this study. We assessed plant cover and antiherbivore resistance traits to assess the extent to which they accounted for the variation in specialization and strength of interactions among species in a plant-herbivore network. We studied a tropical antagonistic network including a diverse herbivore-host plant assemblages in different habitat types and climatic seasons, including host plants with different life histories. Particular combinations of leaf toughness, trichome density, and phenolic compounds influenced herbivore specialization and host species strength, but with a significant spatiotemporal variation among plant life histories. Conversely, plant-herbivore network parameters were not influenced by plant cover. Our study highlights the importance of species-specific resistance traits of plants to understand the ecological and evolutionary consequences of plant-herbivore interaction networks. The novelty of our research lies in the use of a trait-based approach to understand the variation observed in diverse plant-herbivore networks.

A new Pennsylvanian pollen organ from northwestern Missouri with affinities in the Lyginopteridales

An Upper Pennsylvanian locality (Bonner Springs Shale, Kansas City Group, Middle Missourian) in western Missouri contains a diverse and well-preserved fossil assemblage of both plants and arthropods. The plants are preserved as impressions and compressions, and include fertile and vegetative remains of various sphenopsids, lycopsids, ferns, seed ferns, cordaites and conifers. The discovery of a branching system with lyginopterid pollen organs, Parkvillia northcuttii, demonstrates that this group of Paleozoic seed ferns was more diverse and complex than previously known. The fertile structure is characterized by multiple levels of branching with the penultimate branches alternately arranged; ultimate rachises bearing 6–10 alternately arranged, slightly flattened, shield-shaped synangia. Synangia are approximately 5mm in diameter and each consists of a cap with up to 18 sporangia attached to the abaxial surface. The radial and trilete pollen is ornamented by grana and coni. Also in the assemblage are small radially symmetrical ovules and sphenopterid foliage, suggesting that this assemblage contains multiple lyginopterid taxa. The orientation of sporangia and features of the synangia, together with the three-dimensional branching, indicate a morphological pattern that has not been recognized within the Lyginopteridaceae.

Laurinoxylon chalatenangensis sp. nov. from the Miocene Chalatenango Formation, El Salvador

Fossil woods from Miocene sediments in El Salvador, collected in rocks of the Chalatenango Formation, have yielded a diverse plant assemblage in need of detailed studies. This new report of Laurinoxylon chalatenangensis sp. nov. Cevallos-Ferriz, Cerón-López et Flores-Rocha, is based on the combination of wood anatomical characters like distinct growth rings, diffuse porosity, vessel elements solitary and in multiple radials of 2–4, occasionally larger, simple and occasionally scalariform perforation plate, intervessel pits alternate, large elliptical vessel element-ray pits with reduced borders, septate thin-walled fibers, 1–4 seriate heterocelular rays, axial parenchyma scanty paratracheal, and oil cells associated with rays and among the fibers. Its presence in the Chalatenango Fm., and similarity to the Chiapas Laurinoxylon, suggest that this lineage extended its distribution southwards through the Neoegene. This record adds a new species to the growing list of Neotropical taxa that were present in Mexico prior to the great exchange of biota in the Americas.

Exploring the fossil history of pleurocarpous mosses: Tricostaceae fam. nov. from the Cretaceous of Vancouver Island, Canada.

Mosses, very diverse in modern ecosystems, are currently underrepresented in the fossil record. For the pre-Cenozoic, fossil mosses are known almost exclusively from compression fossils, while anatomical preservation, which is much more taxonomically informative, is rare. The Lower Cretaceous of Vancouver Island (British Columbia, Canada) hosts a diverse anatomically preserved flora at Apple Bay. While the vascular plant component of the Apple Bay flora has received much attention, the numerous bryophytes identified at the locality have yet to be characterized. Fossil moss gametophytes in more than 20 carbonate concretions collected from the Apple Bay locality on Vancouver Island were studied in serial sections prepared using the cellulose acetate peel technique. We describe Tricosta plicata gen. et sp. nov., a pleurocarpous moss with much-branched gametophytes, tricostate plicate leaves, rhizoid-bearing bases, and delicate gametangia (antheridia and archegonia) borne on specialized branches. A new family of hypnanaean mosses, Tricostaceae fam. nov., is recognized based on the novel combination of characters of T. plicata. Tricosta plicata reveals pleurocarpous moss diversity unaccounted for in extant floras. This new moss adds the first bryophyte component to an already diverse assemblage of vascular plants described from the Early Cretaceous at Apple Bay and, as the oldest representative of the Hypnanae, provides a hard minimum age for the group (136 Ma).

Facies architecture and palaeoenvironmental implications of the upper Cretaceous (Santonian) Csehbánya formation at the Iharkút vertebrate locality (Bakony Mountains, Northwestern Hungary)

The Csehbánya Formation (Santonian), exposed in the Iharkút open-pit, Bakony Mountains, Hungary, is made up of a cyclic alternation of conglomerate, sandstone, and variegated siltstone and clay deposited in a fluviolacustrine environment. As a result of continuous excavation since 2002 it has yielded rich and diverse continental vertebrate and plant assemblages. A facies and architectural analysis of the Csehbánya Formation at this location identified four main lithofacies associations with eight subtypes consisting of (1) lenticular sandstones representing river channels, (2) conglomerates with sandstone (coarse grained likewise representing channel deposits), (3) heterolithic-channel fill (high density flash flow deposits) (4) splay sandstones produced by crevasse splays, (5) dark sandy siltstone (small-scale stagnant pool deposits with high organic content), (6) greenish-grey claystone (deposits of shallow lakes and ponds), (7) reddish (moderately drained) paleosols, and (8) yellowish, mottled (hydromorphic) paleosols.The sedimentological investigations revealed that the terrestrial deposits exposed by the Iharkút open-pit were formed in an anastomosing fluvial system because: (i) the alluvial architecture is characterized by large proportion of overbank deposits encasing the channel sandstone bodies, (ii) the ribbon shaped sandstone bodies are dominant, (iii) cross-bedding and lateral accretion are almost completely absent in the channel fill deposits and (iv) the sandstone bodies are clearly isolated from each other, embedded in floodplain sediments, suggesting multiple co-existing channels.The most important vertebrate fossil site (SZ-6) was examined in special detail because it shows peculiar lithological features. The layers richest in fossils (Unit 1) of SZ-6 site are interpreted as a lag deposit formed during an episodic high density flash flood event representing a relatively short time interval, i.e., probably within a single rainy season.