Extant Ecosystems Research Articles

Exceptional preservation of a marine tapeworm tentacle in Cretaceous amber

Parasites are ubiquitous in extant ecosystems but rarely preserved in the geological record, especially parasitic worms (helminths). One such group is Cestoda (tapeworms), a specialized endoparasitic group of platyhelminths (flatworms). They have a complex lifecycle with at least two hosts, infecting all major groups of vertebrates. However, their fossil record is extremely sparse due to their soft tissue and concealed habitats, with the only widely accepted example before the Quaternary being eggs discovered in a shark coprolite from the Permian. The lack of body fossils greatly hampers our understanding of their early evolution. We report a slender, armed fossil from mid-Cretaceous Kachin (Myanmar) amber (ca. 99 Ma). This fossil displays unique external (armature pattern) and internal (partially invaginated tentacle and rootless hooks) features that are most consistent with the tentacles of extant trypanorhynch tapeworms that parasitize marine elasmobranchs (mainly sharks and rays). Our study thus probably provides not only the first partial body fossil of a tapeworm, but also arguably the most convincing body fossil of a flatworm. In addition, the exquisite invaginated tentacle inside the fossil highlights that amber can preserve the internal structure of helminths. Remarkably, nearly all extant trypanorhynchs are endoparasites of marine elasmobranchs, thus our study provides an exceptional example of a marine endoparasite trapped in terrestrial amber.

Body size estimation from isolated fossil bones reveals deep time evolutionary trends in North American lizards.

Lizards play vital roles in extant ecosystems. However, their roles in extinct ecosystems are poorly understood because the fossil record of lizards consists mostly of isolated bones. This makes it difficult to document changes in lizard morphology and body size over time, which is essential for studies of lizard paleoecology and evolution. It is also difficult to compare available fossil lizard data with existing sources of extant lizard data because extant studies rarely measure individual bones. Furthermore, no previous study has regressed measurements of individual bones to body length across crown lizard groups, nor tested those regressions on fossil skeletons. An extensive dataset of individual bone measurements from extant lizards across crown taxonomic groups is here employed to develop novel methods for estimating lizard body size from isolated fossil elements. These methods were applied to a comparably large dataset of fossil lizard specimens from the robust Paleogene record (66-23 Ma) of the Western Interior of North America. This study tests the hypothesis that anatomical proportions have been conserved within higher-level crown lizard groups since the Paleogene and can therefore be used to reconstruct snout-vent length (SVL) and mass for fossil specimens referred to the same groups. Individual bones demonstrated strong correlation with SVL in extant as well as fossil lizard specimens (R2 ≥ 0.69). Equations for mass estimation from individual bones were derived from the SVL regressions using published equations for calculating lizard body mass from SVL. The resulting body size estimates from regression equations for the entire fossil dataset revealed that lizards reached greatest maximum body size in the middle Paleogene, with the largest size class dominated by anguid lizards that exceeded 1 meter in SVL and 1.5 kg in body mass. Maximum body size decreased to under 400 mm and below 1.5 kg in the late Paleogene. No association was found between changes in maximum lizard body size and marine isotope proxies of global temperature through the Paleogene. This is the first study to investigate body size evolution across lizard clades over a deep time interval and for a large geographic region. The proposed methods can be used to generate body size regressions and provide estimates of body size for isolated lizard bones referred to any crown group.

From meat availability to hominin and carnivore biomass: A paleosynecological approach to reconstructing predator-prey biomass ratios in the Pleistocene

Reconstructing the conditions and circumstances under which the human lineage evolved is of great interest to those disciplines related to human evolution, especially in fields such as archaeoecology and human paleoecology. A mathematical model was presented almost a decade ago aimed to reconstructing the human populations that the Pleistocene paleoecosystems could support. This model followed a paleosynecological perspective, being focused on: (i) estimating the availability of meat resources in the paleoecosystems, as these resources are vital for human survival; and (ii) measuring the level of competition for these resources among the members of the carnivore guild, including hominins. The model has been applied since then to several Pleistocene localities of Europe, with particular emphasis on the Orce and Sierra de Atapuerca sites. In this study, we use the model for estimating predator-prey biomass ratios and compare the model outputs with the values measured in present-day African ecosystems. The results obtained confirm that our paleosynecological approach provides estimates of predator-prey biomass ratios that are broadly similar to those measured in the extant ecosystems. However, our estimates tend to be slightly higher than expected, which is probably due to the weight of species that satisfy part of their nutritional requirements with resources other than the meat from large herbivores. This allows us to assume that our model performs relatively well, although it has room for methodological improvements.

Shallow-marine testate amoebae with internal structures from the Lower Devonian of China

Testate amoebae, a polyphyletic protist group inhabiting a wide variety of extant ecosystems, have evolved as far back as early Neoproterozoic. However, their fossil record is discontinuous and biased toward empty shells. Here, we report an arcellinid testate amoeba species, Cangwuella ampulliformis gen. nov., sp. nov., from a shallow-marine community in the Early Devonian of Guangxi, southwestern China. With the aid of scanning electron microscopy and X-ray micro-tomography, we find that the shell of our testate amoeba contains some acetabuliform structures. Although such configuration does not match exactly with the known internal structures in extant testate amoebae, our fossils highlight the potential of exploring the ecological relationships between fossil testate amoebae and their associated organisms, and increase our knowledge on the diversity of testate amoebae in Early Devonian environments.

Mayflies as resource pulses in Jurassic lacustrine ecosystems

Abstract Resource pulses, occasional events of ephemeral resource superabundance, represent a fundamental mechanism by which energy, nutrients, and biomass are transported across ecotones. They are widespread in extant ecosystems; however, little is known about their deep-time record. We report the earliest-known mayfly swarm from the Early Jurassic Xiwan biota of southern China. Our taphonomic and sedimentological analyses show that these mayflies were buried on the bottom of a calm lake after post-mating death. Our suite of analyses suggests that the complex mating-swarm behavior was already well established in mayflies by the Early Jurassic. More importantly, our find represents the earliest-known resource pulse of insects, a mechanism that can play a substantial role in nutrient transport from aquatic ecosystems to surrounding terrestrial ecosystems. Such an aquatic-terrestrial ecosystem linkage may be a key novelty in Mesozoic lacustrine ecosystems. Our results high-light the underappreciated ecological significance of insects in deep-time terrestrial ecology.

Diet of Mesozoic toothed birds (Longipterygidae) inferred from quantitative analysis of extant avian diet proxies

BackgroundBirds are key indicator species in extant ecosystems, and thus we would expect extinct birds to provide insights into the nature of ancient ecosystems. However, many aspects of extinct bird ecology, particularly their diet, remain obscure. One group of particular interest is the bizarre toothed and long-snouted longipterygid birds. Longipterygidae is the most well-understood family of enantiornithine birds, the dominant birds of the Cretaceous period. However, as with most Mesozoic birds, their diet remains entirely speculative.ResultsTo improve our understanding of longipterygids, we investigated four proxies in extant birds to determine diagnostic traits for birds with a given diet: body mass, claw morphometrics, jaw mechanical advantage, and jaw strength via finite element analysis. Body mass of birds tended to correspond to the size of their main food source, with both carnivores and herbivores splitting into two subsets by mass: invertivores or vertivores for carnivores, and granivores + nectarivores or folivores + frugivores for herbivores. Using claw morphometrics, we successfully distinguished ground birds, non-raptorial perching birds, and raptorial birds from one another. We were unable to replicate past results isolating subtypes of raptorial behaviour. Mechanical advantage was able to distinguish herbivorous diets with particularly high values of functional indices, and so is useful for identifying these specific diets in fossil taxa, but overall did a poor job of reflecting diet. Finite element analysis effectively separated birds with hard and/or tough diets from those eating foods which are neither, though could not distinguish hard and tough diets from one another. We reconstructed each of these proxies in longipterygids as well, and after synthesising the four lines of evidence, we find all members of the family but Shengjingornis (whose diet remains inconclusive) most likely to be invertivores or generalist feeders, with raptorial behaviour likely in Longipteryx and Rapaxavis.ConclusionsThis study provides a 20% increase in quantitatively supported fossil bird diets, triples the number of diets reconstructed in enantiornithine species, and serves as an important first step in quantitatively investigating the origins of the trophic diversity of living birds. These findings are consistent with past hypotheses that Mesozoic birds occupied low trophic levels.

The Humpty Dumpty Effect on Planet Earth

Humans have treated the earth harshly. Degradation of extant ecosystems leaves little chance that they might function as they have in the past. Putting back the pieces and restoring what once existed is no longer possible even with re-wildling—an effect analogous to the Humpty Dumpty parable. However, we do have conservation successes after concerted efforts related to habitat protection, species and ecosystem restoration, and planning. While the changes to Earth's biosphere are grave, necessitating immediate and exhaustive action, our Humpty Dumpty world reassembles with progressive conservation victories at all regional scales from local to global which should lead to a modicum of optimism rather than despair. We suggest that to be truly effective our work as academic scientists must be more than publishing in scholarly journals. At the least, this should include changes in how success is measured in science and how university tenure is awarded.

Thermal performance of the European flat oyster, Ostrea edulis (Linnaeus, 1758)—explaining ecological findings under climate change

Climate change challenges marine organisms by constraining their temperature-dependent scope for performance, fitness, and survival. According to the concept of Oxygen and Capacity Limited Thermal Tolerance (OCLTT), the overall thermal performance curve relates to an organism’s aerobic power budget, its overall aerobic scope for growth, exercise, reproduction, and other performances. We hypothesize that physiological principles shaping tolerance in extant ecosystems have also been operative during climatic changes in the distant past. To compare response patterns in extant fauna and their palaeo-relatives, we started here by studying the metabolic background of performance in the European flat oyster Ostrea edulis at organismic and cellular levels, focusing on the acute thermal window and the metabolic changes towards upper lethal temperatures. We investigated the response of the oysters (pre-acclimated at 12 °C) to a short-term warming protocol (by 2 °C every 48 h) from 14 to 36 °C which we identified as the lethal temperature. At the organismic level, heart and filtration rates were recorded. Gill metabolites were studied by 1H NMR spectroscopy to address thermal responses at the cellular level. Feeding activity by O. edulis (assessed by the filtration rates) was highest between 18 and 24 °C when overall energy expenditure (indicated by heart rate as a proxy for routine metabolic rate) was moderate. We conclude that this range reflects the thermal optimum of this species. Beyond 26 °C, the gill tissue of O. edulis became partly anaerobic, and cardiac dysfunction (arrhythmia) developed at 28 °C followed by an Arrhenius break point (30 °C). This mirrors performance constraints and indicates a wide temperature range of passive tolerance which may be a long-standing characteristic of ostreids supporting survival in extreme environments as well as during past and present climate oscillations.

Fossil fern rhizomes as a model system for exploring epiphyte community structure across geologic time: evidence from Patagonia.

BackgroundIn extant ecosystems, complex networks of ecological interactions between organisms can be readily studied. In contrast, understanding of such interactions in ecosystems of the geologic past is incomplete. Specifically, in past terrestrial ecosystems we know comparatively little about plant biotic interactions besides saprotrophy, herbivory, mycorrhizal associations, and oviposition. Due to taphonomic biases, epiphyte communities are particularly rare in the plant-fossil record, despite their prominence in modern ecosystems. Accordingly, little is known about how terrestrial epiphyte communities have changed across geologic time. Here, we describe a tiny in situ fossil epiphyte community that sheds light on plant-animal and plant-plant interactions more than 50 million years ago.MethodsA single silicified Todea (Osmundaceae) rhizome from a new locality of the early Eocene (ca. 52 Ma) Tufolitas Laguna del Hunco (Patagonia, Argentina) was studied in serial thin sections using light microscopy. The community of organisms colonizing the tissues of the rhizome was characterized by identifying the organisms and mapping and quantifying their distribution. A 200 × 200 µm grid was superimposed onto the rhizome cross section, and the colonizers present at each node of the grid were tallied.ResultsPreserved in situ, this community offers a rare window onto aspects of ancient ecosystems usually lost to time and taphonomic processes. The community is surprisingly diverse and includes the first fossilized leafy liverworts in South America, also marking the only fossil record of leafy bryophyte epiphytes outside of amber deposits; as well as several types of fungal hyphae and spores; microsclerotia with possible affinities in several ascomycete families; and evidence for oribatid mites.DiscussionThe community associated with the Patagonian rhizome enriches our understanding of terrestrial epiphyte communities in the distant past and adds to a growing body of literature on osmundaceous rhizomes as important hosts for component communities in ancient ecosystems, just as they are today. Because osmundaceous rhizomes represent an ecological niche that has remained virtually unchanged over time and space and are abundant in the fossil record, they provide a paleoecological model system that could be used to explore epiphyte community structure through time.

Revisión de las avispas figítidas fósiles (Insecta: Hymenoptera: Cynipoidea) descritas de depósitos de compresión durante la primera mitad del siglo XX

En la presente investigación se revisan los holotipos de las avispas fósiles del Cenozoico atribuidas a la familia Figitidae, las cuales fueron descritas en la primera mitad del siglo XX por Charles T. Brues y Georg Statz provenientes de los yacimientos de Florissant (EE.UU.) y Rott-am-Siebengebirge (Alemania), respectivamente. Se proponen los siguientes cambios taxonómicos: Palaeogronotoma? sola (Brues) n. comb., Aulacidea rotundata (Statz) n. comb., A. plana (Statz) n. comb. y A. spiniger (Statz) n. comb. Los cambios taxonómicos para las tres últimas especies indicadas han implicado su emplazamiento en el género actual Aulacidea, de la familia Cynipidae, y por lo tanto no pertenecen a la familia Figitidae como se consideró originalmente en 1938. La revisión de una especie fósil originalmente descrita en 1919, conservada en ámbar báltico, muestra que posee un conjunto único de caracteres para la familia Cynipidae, permitiendo la descripción de una nueva tribu: Kinseycynipsini n. tribe. Se hacen indicaciones taxonómicas referidas a otras tres especies de cinípidos fósiles. La adscripción taxonómica correcta de las especies fósiles de figítidos y cinípidos descritas hace alrededor de un siglo es importante para entender la evolución de estas dos familias de cinipoideos, las cuales desempeñan un importante papel ecológico en los ecosistemas terrestres actuales. También se proporcionan listas actualizadas de las especies fósiles de figítidos y cinípidos conocidas.

Mass extinctions drove increased global faunal cosmopolitanism on the supercontinent Pangaea

Mass extinctions have profoundly impacted the evolution of life through not only reducing taxonomic diversity but also reshaping ecosystems and biogeographic patterns. In particular, they are considered to have driven increased biogeographic cosmopolitanism, but quantitative tests of this hypothesis are rare and have not explicitly incorporated information on evolutionary relationships. Here we quantify faunal cosmopolitanism using a phylogenetic network approach for 891 terrestrial vertebrate species spanning the late Permian through Early Jurassic. This key interval witnessed the Permian–Triassic and Triassic–Jurassic mass extinctions, the onset of fragmentation of the supercontinent Pangaea, and the origins of dinosaurs and many modern vertebrate groups. Our results recover significant increases in global faunal cosmopolitanism following both mass extinctions, driven mainly by new, widespread taxa, leading to homogenous ‘disaster faunas’. Cosmopolitanism subsequently declines in post-recovery communities. These shared patterns in both biotic crises suggest that mass extinctions have predictable influences on animal distribution and may shed light on biodiversity loss in extant ecosystems.

Synthetic microbiology: from analogy to methodology.

Synthetic microbiology: from analogy to methodology.

Algal ancestor of land plants was preadapted for symbiosis

Colonization of land by plants was a major transition on Earth, but the developmental and genetic innovations required for this transition remain unknown. Physiological studies and the fossil record strongly suggest that the ability of the first land plants to form symbiotic associations with beneficial fungi was one of these critical innovations. In angiosperms, genes required for the perception and transduction of diffusible fungal signals for root colonization and for nutrient exchange have been characterized. However, the origin of these genes and their potential correlation with land colonization remain elusive. A comprehensive phylogenetic analysis of 259 transcriptomes and 10 green algal and basal land plant genomes, coupled with the characterization of the evolutionary path leading to the appearance of a key regulator, a calcium- and calmodulin-dependent protein kinase, showed that the symbiotic signaling pathway predated the first land plants. In contrast, downstream genes required for root colonization and their specific expression pattern probably appeared subsequent to the colonization of land. We conclude that the most recent common ancestor of extant land plants and green algae was preadapted for symbiotic associations. Subsequent improvement of this precursor stage in early land plants through rounds of gene duplication led to the acquisition of additional pathways and the ability to form a fully functional arbuscular mycorrhizal symbiosis.

Reconstructing Extinct Plant Water Use for Understanding Vegetation–Climate Feedbacks: Methods, Synthesis, and a Case Study Using the Paleozoic-Era Medullosan Seed Ferns

Vegetation affects feedbacks in Earth's hydrologic system, but is constrained by physiological adaptations. In extant ecosystems, the mechanisms controlling plant water used can be measured experimentally; for extinct plants in the recent geological past, water use can be inferred from nearest living relatives, assuming minimal evolutionary change. In deep time, where no close living relatives exist, fossil material provides the only information for inferring plant water use. However, mechanistic models for extinct plant water use must be built on first principles and tested on extant plants. Plants serve as a conduit for water movement from the soil to the atmosphere, constrained by tissue-level construction and gross architecture. No single feature, such as stomata or veins, encompasses enough of the complexity underpinning water-use physiology to serve as the basis of a model of functional water use in all (or perhaps any) extinct plants. Rather, a “functional whole plant” model must be used. To understand the interplay between plant and atmosphere, water use in relation to environmental conditions is investigated in an extinct plant, the seed fernMedullosa((Division Pteridospermatophyta), by reviewing methods for reconstructing physiological variables such as leaf and stem hydraulic capacity, photosynthetic rate, transpiration rate, stomatal conductance, and albedo. Medullosans had the potential for extremely high photosynthetic and assimilation rates, water transport, stomatal conductance, and transpiration—rates comparable to later angiosperms. When these high growth and gas exchange rates of medullosans are combined with the unique atmospheric gas composition of the late Paleozoic atmosphere, complex vegetation-environmental feedbacks are expected despite their basal phylogenetic position relative to post-Paleozoic seed plants.

Arbuscular mycorrhizal fungi in a voltzialean conifer from the Triassic of Antarctica

Mycorrhizas are intimate mutualistic relationships between plants and fungi that represent an integral component of ancient and extant ecosystems. These symbioses have been established for at least 400million years and are found in numerous fossil plant groups, including early land plants, seed ferns, and cordaitaleans. In modern ecosystems, it is common for different types of mycorrhizas to occur within a single plant; however, fossil evidence of this is exceedingly scarce. A vesicular–arbuscular mycorrhiza is described in Notophytum krauselii (voltzialean conifers) based on permineralizations from the Middle Triassic of Antarctica. This symbiosis occurs in young non-nodular roots and is characterized by fungal hyphae, vesicles, and arbuscules within a discrete zone of the root cortex. Together with the mycorrhizal root nodules described previously for N. krauselii, this discovery represents only the second record of multiple types of mycorrhizae occurring within the same fossil plant, and provides important information on the system of interactions that may have allowed voltzialean conifers to survive in an extreme paleoenvironment.

Highly resolved early Eocene food webs show development of modern trophic structure after the end-Cretaceous extinction

Generalities of food web structure have been identified for extant ecosystems. However, the trophic organization of ancient ecosystems is unresolved, as prior studies of fossil webs have been limited by low-resolution, high-uncertainty data. We compiled highly resolved, well-documented feeding interaction data for 700 taxa from the 48 million-year-old latest early Eocene Messel Shale, which contains a species assemblage that developed after an interval of protracted environmental and biotal change during and following the end-Cretaceous extinction. We compared the network structure of Messel lake and forest food webs to extant webs using analyses that account for scale dependence of structure with diversity and complexity. The Messel lake web, with 94 taxa, displays unambiguous similarities in structure to extant webs. While the Messel forest web, with 630 taxa, displays differences compared to extant webs, they appear to result from high diversity and resolution of insect–plant interactions, rather than substantive differences in structure. The evidence presented here suggests that modern trophic organization developed along with the modern Messel biota during an 18 Myr interval of dramatic post-extinction change. Our study also has methodological implications, as the Messel forest web analysis highlights limitations of current food web data and models.

The oldest North American pachycephalosaurid and the hidden diversity of small-bodied ornithischian dinosaurs

Taphonomic biases dictate how organisms are represented in the fossil record, but their effect on studies of vertebrate diversity dynamics is poorly studied. In contrast to the high diversity and abundance of small-bodied animals in extant ecosystems, small-bodied dinosaurs are less common than their large-bodied counterparts, but it is unclear whether this reflects unique properties of dinosaurian ecosystems or relates to taphonomic biases. A new, fully domed pachycephalosaurid dinosaur, Acrotholus audeti, from the Santonian of Alberta predates incompletely domed taxa, and provides important new information on pachycephalosaur evolution and the completeness of the ornithischian fossil record. Here we provide the first empirical evidence that the diversity of small-bodied ornithischian dinosaurs is strongly underestimated based on ghost lineages and the high proportion of robust and diagnostic frontoparietal domes compared with other pachycephalosaur fossils. This suggests preservational biases have a confounding role in attempts to decipher vertebrate palaeoecology and diversity dynamics through the Mesozoic.

Handbook for opening the vault: a helpful guide to using and interpreting paleontological data

book reviews ISSN 1948‐6596 Handbook for opening the vault: a helpful guide to using and in‐ terpreting paleontological data Paleontology in Ecology and Conservation. Julien Louys (editor), 2012, Springer. 273 pp. $129/ £90 (hardback) ISBN: 9783642250378; http://www.springer.com In a past incarnation as a research student working on nature reserve selection and de‐ sign algorithms, I kept coming across provisos in the conservation planning literature such as ‘we need long‐term data on populations and ecosystems but because these are largely un‐ available we must rely on the limited, static species data that are available.’ I wondered why the palaeo‐record was not being used to fill this information gap. The first time I sug‐ gested this to a colleague, the response was predictable: what would data spanning ‘geologic’ time offer to modern conservation efforts? However, as is argued in this book, the fossil record is not limited to deep‐time (fossil data can provide insights into changes in extant populations and ecosystems over the past few centuries). Further, ecological data across all time‐scales are necessary for good management that supports the biodiver‐ sity and the ecosystem processes that make ecosystems resilient to environmental change (Mace et al. 2012). This book is aimed at researchers working in ecology and conservation who are interested in making use of the vast amount of informa‐ tion stored within the fossil record. The greatest strength of the book is that it teaches conservation planners how to access the ver‐ tebrate paleontological record, in order to extract the long‐term demographic data that they require. This includes data on animal demographics (mortality, age structure), predator–prey interactions, species richness and abundance, phylogenetic diversity, habi‐ tat usage and biotic recycling of nutrients. Conservation biologists will be interested in the review of evidence from the fossil record of the possible mechanisms by which animal and plant species may respond to future envi‐ ronmental change (extinction/extirpation, re‐ location and adaptation) and the context in which each response is likely to occur (Chapter 6). The authors address in detail the issues in‐ volved in using and interpreting the fossil re‐ cord to understand and manage modern eco‐ systems, such as differences in scale (temporal, spatial and taxonomic) between palaeoecology and neo‐ecology, as well as the taphonomic processes that affect the compo‐ sition of the fossil record (i.e. the death as‐ semblage). However, the unique contribution of this book is the focus on the positive as‐ pects of these differences, including guidance on dealing with potential problems. For ex‐ ample, the process of taphonomy—the crea‐ tion, movement, deposition and preservation of fossils—is described in terms of the novel information it offers (Chapter 5) to neo‐ ecological research. There is also an excellent review of the spatial, temporal and taxonomic scales of long‐term neo‐ecological studies, and guidance on ways that palaeoecological data can be integrated with these (Chapter 4) in order to extend the time scale of our obser‐ vations of biodiversity and ecological and evo‐ lutionary processes. The fossil record does not only provide depth in terms of temporal scales; the integration of multiple fossil records across space provides insights into the macro‐scale ecological and evolutionary processes that are likely to be affected by current and future global environ‐ mental change. This book provides a number of good examples of integrating records frontiers of biogeography 5.1, 2013 — © 2013 the authors; journal compilation © 2013 The International Biogeography Society

Phototrophic sulfide oxidation: environmental insights and a method for kinetic analysis

Previously, we presented data that indicated microbial sulfide oxidation would out-compete strictly chemical, abiotic sulfide oxidation reactions under nearly all conditions relevant to extant ecosystems (Luther et al., 2011). In particular, we showed how anaerobic microbial sulfide oxidation rates were several orders of magnitude higher than even metal catalyzed aerobic sulfide oxidation processes. The fact that biotic anaerobic sulfide oxidation is kinetically superior to abiotic reactions implies that nearly all anaerobic and sulfidic environments should host microbial populations that oxidize sulfide at appreciable rates. This was likely an important biogeochemical process during long stretches of euxinia in the oceans suggested by the geologic record. In particular, phototrophic sulfide oxidation allows the utilization of carbon dioxide as the electron acceptor suggesting that this process should be particularly widespread rather than relying on the presence of other chemical oxidants. Using the Chesapeake Bay as an example, we argue that phototrophic sulfide oxidation may be more important in many environments than is currently appreciated. Finally, we present methodological considerations to assist other groups that wish to study this process.

Pre-Cretaceous Agaricomycetes yet to be discovered: Reinvestigation of a putative Triassic bracket fungus from southern Germany

Agaricomycetes are major components of extant terrestrial ecosystems; however, their fruiting bodies are exceedingly rare as fossils. Reinvestigation of a peculiar fossil from Late Triassic sediments of southern Germany interpreted as a bracket fungus revealed that this fossil in fact represents a wood abnormality, resulting from injury to the cambium and subsequent callus growth in a <i>Baieroxylon</i> -like ginkgoalean wood. As a result, the fossil record of the Agaricomycetes does not yet pre-date the Early Cretaceous, suggesting a late diversification of basidiomycetes possessing large fruiting bodies. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.201200006" target="_blank">10.1002/mmng.201200006</a>