Lagerstatte Research Articles

An inter-comparison study of three stomatal-proxy methods for CO2 reconstruction applied to early Jurassic Ginkgoales plants

The inverse relationship between concentrations of CO2 in the atmosphere (pCO2) and the stomatal index of vascular plant has been widely used to estimate ancient levels of atmospheric CO2. However, some atmospheric concentration of CO2 in the geological past (paleo-CO2) estimates show little congruence because they are derived using different correlative methods, or from different fossil plant species with different calibration approaches. Here we apply three methods, including (1) the empirical method of McElwain (1998), (2) the empirical method of Barclay and Wing (2016) and (3) the mechanistic method of Franks et al., (2014) to a single fossil Ginkgo species (Ginkgoites marginatus) to track and assess their consistency of pCO2 estimates for the Early Jurassic. By using an inter-comparison of three methods, a high degree of consistency in pCO2 estimates and trends has been observed in two empirical proxy methods. In addition, the mechanistic method and both the empirical methods also show generally good consistent paleo-CO2 estimates at the bed-level. To test the congruence of paleo-CO2 estimates, we also apply all three methods to one additional Ginkgoalean fossil species (Sphenobaiera huangii). All three methods show species-dependent uncertainty in paleo-CO2 estimates when applied to different Ginkgalean fossil species collected from the same fossiliferous bed. Moreover, considering the potential effect of guard cell size to the mechanistic method, the genome size of fossil and living Ginkgo taxa was analyzed based on the significant positive relationship between genome size and guard cell size. The result demonstrates that a likely occurrence of polyploidy in Sphenobaiera huangii may result in underestimated paleo-CO2 when applying mechanistic method due to an increase in the size of the stomatal complex.

Sauropod dinosaur fossils from the Kem Kem and extended ‘Continental Intercalaire’ of North Africa: A review

The Cretaceous (likely Aptian-Cenomanian) Kem Kem beds of Morocco are famous for their fossil-richness, including theropods, and several sauropod body fossils, such as Rebbachisaurus garasbae, as well as isolated sauropod teeth. Deposits from this particular age, however, stretch across Algeria and Tunisia, with possibly contemporaneous fossiliferous beds also being known from Egypt and Niger. Although the sediments of North Africa have yielded more complete sauropod specimens in recent years dated to either Cenomanian or Campanian-Maastrichtian, in general, these sites are not well-known. A recent study on isolated sauropod teeth from Morocco and Algeria revealed that a diverse sauropod fauna existed, and, moreover, evidence has been found of sauropod migration from Africa to Europe in the Cretaceous. In order to provide a better overview of the sauropod presence in the Albian-Cenomanian of North Africa, an overview of all sauropod material known from this time is necessary. Therefore, several previous reports on sauropod fossils and teeth from the Kem Kem and the ‘Continental Intercalaire’ of North Africa are here reviewed and summarized.

The first Elcanidae (Orthoptera, Elcanoidea) from the Daohugou fossil bed of northeastern China.

A new species of Elcanidae (Orthoptera, Elcanoidea), Parelcana pulchmaculasp. nov., is described based on four new specimens from the Middle Jurassic Jiulongshan Formation of northeastern China. The new species differs from all other known Archelcaninae species by its combination of wing-venation characters. This new finding improves our knowledge of variation on wing venation in elcanid insects and constitutes the first record of Elcanidae from the Daohugou fossil bed (Yanliao Biota) of northeastern China.

Paleoenvironmental context and significance of a partial elasmosaurid skeleton from the Albian of Haute-Provence, France

The Early–Late Cretaceous transition (late Albian–early Cenomanian; ~100 Ma) witnessed marked environmental changes and a deep reorganization of the marine fauna. The impact of these environmental and biotic changes on Tethyan marine vertebrates is poorly understood, due to a fragmentary fossil record. Here we report upper Albian marine vertebrate remains, including a partially articulated plesiosaurian skeleton, from a fossiliferous glauconite-rich bed in the Alpes de Haute-Provence, France. The fossiliferous horizon produced a diversified invertebrate fauna including ammonoids and belemnoids. The ammonite fauna is abundant and diversified, indicating the Mortoniceras fallax ammonite Zone. The calcareous nannofossil biomarkers date the bed to the NC10a Zone. The fossiliferous bed consists of glauconitic marls enriched in planktic foraminifera and occurs amongst a monotonous succession of alternating marlstones and limestone beds. The vertebrate fauna consists of chondrichthyans and marine reptiles. Chondrichthyans are represented by five Lamniformes species (dominated by Sphenodus) and comprise predator taxa probably living in open marine temperate waters. The site yielded a large, partial post-cranial plesiosaurian skeleton with articulated elements, belonging to an elasmosaurid and representing one of the most complete Albian plesiosaurian specimens known from Europe. The abundance and preservation of the collected fossil remains are best explained by their concentration during a basin-scale episode of very low sedimentation corresponding to a major episode of marine transgression, associated with a lower oxygenation of bottom waters. These findings indicate that the newly discovered fossiliferous bed holds promising clues about the evolutionary history of major groups of marine vertebrates and ammonites near the Early–Late Cretaceous transition.

Callovian (Middle Jurassic) terebratulide brachiopods from the Jordan Valley (northwestern Jordan)

ABSTRACT Middle Jurassic terebratulide brachiopods from the Jordan Valley are herein revised and new taxa are added to the previous faunal list. The Callovian rocks (Mughanniyya Formation) of the Tel el Dhahab section has allowed recognising two new terebratulide taxa: Kutchithyris simoni sp. nov. and Trigonithyris wilsoni sp. nov, which are formally described herein. Additionally, three terebratulide species: Bihenithyris barringtoni, Ptyctothyris daghaniensis, and Sphriganaria cardioides are reported for the first time from Jordan, all of them recorded together Bihenithyris weiri, a more widespread taxa in the Ethiopian Province. The Callovian Mughanniyya Formation of northwest Jordan is dominated by highly fossiliferous limestone beds intercalated with marlstones deposited on a low angle carbonate ramp in a shallow protected, inner shelf setting. Brachiopods of the Jordanian Mughanniyya Formation can be correlated with the Callovian brachiopod faunas of the Aroussiah Formation in Sinai and the Zohar and Matmor formations in southern Israel. The high degree of endemism of the terebratulide brachiopods under study here is yet another confirmation of the pronounced Middle Jurassic endemism along the southern Tethyan margin of the Ethiopian Province.

Anatomical revision of the Australian teleosts Cavenderichthys talbragarensis and Waldmanichthys koonwarri impacting on previous phylogenetic interpretations of teleostean relationships

Bean, L. B. & Arratia, G., 4 October 2019. Anatomical revision of the Australian teleosts Cavenderichthys talbragarensis and Waldmanichthys koonwarri impacting on previous phylogenetic interpretations of teleostean relationships. Alcheringa 44, 121–159. ISSN 0311-5518. Australia has two important sites for Mesozoic fishes. The Talbragar Fossil Fish Bed in New South Wales is a Tithonian freshwater lake deposit containing the iconic form Cavenderichthys talbragarensis, first described in 1895. The Koonwarra Fossil Bed in Victoria is an Albian freshwater lake deposit containing Waldmanichthys koonwarri, first described in 1971. Following the tradition of the time, both species were first ascribed to the historic genus Leptolepis. In 2015, these two species were placed into a newly erected family, Luisiellidae, with the Oxfordian–Tithonian fish Luisiella feruglioi from the Cañadón Calcáreo Formation in Chubut, Argentinian Patagonia. This new family was interpreted as a stem teleost group, closer to Leptolepis coryphaenoides than to the crown-group Teleostei, a contrary hypothesis to previous interpretations that placed Cavenderichthys as a teleost incertae sedis in the crown Teleostei. This paper re-examines the morphological characters of the Australian taxa, including 46 previously undescribed specimens of W. koonwarri, from Museum Victoria. Some of the new characters include the special configuration of the jaws and the position of the quadrate-mandibular articulation; the special vertebral pattern at the level of the abdominal/caudal regions; a stegural-like uroneural in the caudal skeleton; and the structure of the scales. Finding the new characters in Waldmanichthys called for reappraisals of the morphology of Cavenderichthys and Luisiella. In the case of Cavenderichthys, 34 specimens were re-examined, but for specimens of Luisiella, a conservative approach was followed, based on its last morphological description as well as photographs taken more recently. The systematic position of the three Gondwanan taxa was re-evaluated using a pre-existing data matrix including 240 characters and 56 taxa. The new results give a very different scenario, with the three taxa now included in the crown-group Teleostei. The family Luisiellidae is restricted to its type species L. feruglioi. The two Australian fish genera cluster together with the Late Jurassic European genera Leptolepides and Orthogonikleithrus and are now ascribed to the family Orthogonikleithridae. The new results suggest that the three Gondwanan genera are stem taxa to the Osteoglossocephala (osteoglosomorphs plus more advanced teleosts), and their combination of morphological characters has a major effect on the interpretation of basal euteleosts, questioning some previous interpretations, as for instance, the homology of the stegural as an euteleostean character. Lynne B. Bean* [lynne.bean@anu.edu.au], Research School of Earth Sciences, Australian National University, Acton 2001, Australia; Gloria Arratia [garratia@ku.edu], Department of Ecology and Evolutionary Biology and Biodiversity Institute, University of Kansas, Dyche Hall, Lawrence, KS 66045, USA.

Differential Species Responses to Aspects of Resistance to Invasion in Two Columbia Plateau − Protected Areas

Protected-area sagebrush steppe ecosystems are few in number and increasingly important to the North American conservation network as sagebrush steppe faces growing threats from land use, climate change, and invasive species. We analyzed the distribution and abundance of native perennial and invasive annual plants to better understand patterns of plant invasion within two protected areas: John Day Fossil Beds National Monument (JODA), located in central Oregon, and Craters of the Moon National Monument and Preserve (CRMO), located in southeast Idaho. We used multivariate analysis to examine vegetation monitoring datasets and illuminate geographic variation in plant cover along gradients of well-known aspects of resistance to plant invasion (elevation, exposure [slope and aspect], precipitation and proximity to disturbance). Topographically mediated resistance to invasion appeared to manifest in the park with greater topographic variability (JODA), while increased elevation was more strongly associated with resistant sites in the park, which spanned a greater elevational gradient (CRMO). Factors that may mitigate moisture-mediated resistance also differed between sites. Slope and aspect were factors of apparent resistance for bunchgrass communities in JODA, while high crop year precipitation appeared to benefit medusahead (Taeniatherum caput-medusae [L.] Nevski) and the weedy native subshrub broom snakeweed (Gutierrezia sarothrae [Pursh] Britton & Rusby) over bunchgrasses and Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young). Increased elevation and distance to disturbed areas were the most important factors of resistance in forb-rich communities at CRMO, with the invasive annuals cheatgrass (Bromus tectorum L.), tumblemustard (Sisymbrium altissimum L.), and Descurainia spp. Webb & Bethel. invading in low elevations and in close proximity to roads or agricultural fields. Such complexity underscores the idiosyncratic nature of the manifestation of resistance and the need for place-based empirical studies to provide information for guiding protected-area management.

A late Pleistocene human footprint from the Pilauco archaeological site, northern Patagonia, Chile.

The present study describes the discovery of a singular sedimentary structure corresponding to an ichnite that was excavated at the paleo-archaeological site Pilauco (Osorno, Chile). The trace fossil is associated with megafauna bones, plant material and unifacial lithic tools. Here we present a detailed analysis of the Pilauco ichnite and associated sedimentary structures, as well as new radiocarbon data. The ichnological analysis confidently assigns the trace to the ichnospecies Hominipes modernus—a hominoid footprint usually related to Homo sapiens. Some particular characteristics of the Pilauco trace include an elongated distal hallux, lateral digit impressions obliterated by the collapsed sediment, and sediment lumps inside and around the trace. In order to evaluate the origin of the ichnite, trackmaking experiments are performed on re-hydrated fossil bed sediments. The results demonstrate that a human agent could easily generate a footprint morphology equivalent to the sedimentary structure when walking on a saturated substrate. Based on the evidence, we conclude that the trackmaker might well have been a bare-footed adult human. This finding, along with the presence of lithic artifacts in the same sedimentary levels, might represent further evidence for a pre-Clovis South American colonization of northern Patagonia, as originally proposed for the nearby Monte Verde site.

Strontium isotope radiometric dating reveals the late Eocene and Oligocene successions in northern Kuwait

The strata exposed at Jal Az-Zor escarpment in northern Kuwait represent one of the best outcrops in the country, extending over 60 km in length with a cliff-face of around 36 m. The age assignment of these rock units was mostly done during the 1920s to 1960s and was largely based on taxonomy grouping of an oyster-rich bed present at the base of Jal Az-Zor correlated to what appeared to be a similar layer that belongs to the Lower Fars Formation in Iran. In the subsurface, the results of biostratigraphic analysis using different taxonomic groups have suggested ages that position this exposed lithological unit in the range of late Miocene to Pliocene (11.63–2.58 Ma). Due to the lack of radiometric numerical data, the strontium isotope ratio (87Sr/86Sr) age-dating method was applied on carefully selected surface and subsurface samples including an oyster shell, beds with abundant fossils, and calcite cemented specimens. Petrographic, XRD, and SEM-EDX analyses were utilized to determine the rock composition, assist in identifying the biomass, and carbonate content of the samples before performing age dating on selected areas of the sample. Numerical age determination based on (87Sr/86Sr) ratio revealed that an oyster shell taken from the cliff of Jal Az-Zor is 20.53 Ma in age (Aquitanian), the fossiliferous bed exposed at the foot of the escarpment is 24.39 Ma in age (Chattian), and the Sabriyah roadcut beds exhibit an age of 30.32 Ma (Rupelian). The subsurface extracted samples that are dominated by calcite cement uncovered an age range between 36 and 19.41 Ma (Burdigalian to Priabonian). This analysis introduces the late Eocene and Oligocene to Kuwait’s stratigraphy otherwise known to be eroded. The implications of such findings can revamp the Paleogene and Neogene tectonic evolution of Kuwait and potentially lead to the renaming of the undifferentiated Kuwait Group strata to a more representative name, such as the Kuwait Formation that combines the traditional tripartite subdivision of the group.

Revision of the Cretaceous Proctotrupomorpha (Insecta: Hymenoptera) of Australia

Based on new and better images of the fossils, we revise the known Cretaceous Proctotrupomorpha of Australia. The fossils were collected at the Koonwarra Fossil Bed, the only source of Cretaceous Proctotrupomorpha in Australia so far. The revision results in the following new taxa and new attributions: Cretacoformicidae fam. nov. in Proctotrupomorpha superfamily incertae sedis, including Cretacoformica explicata Jell & Duncan, 1986 from the Koonwarra Fossil Bed and Iberapria perialla Engel et al., 2013 from Lower Cretaceous Spanish amber, possibly related to Serphitoidea s.l. (including Mymarommatoidea and Yurapriidae) and Chalcidoidea, and Koonwarrus katya gen. et sp. nov. in Proctotrupomorpha incertae familiae from the Koonwarra Fossil Bed, possibly related to Proctotrupoidea, Diaprioidea and/or Platygastroidea. Two other proctotrupomorph fossils from the Koonwarra Fossil Bed are confirmed to represent Proctotrupidae. Through the survey of Cretaceous Australian Proctotrupomorpha, which are preserved just in very few known fossils, the necessity of additional research on Australian Cretaceous Hymenoptera and continuing search for insect fossils in the Koonwarra Fossil Bed, as well as for additional research on known fossils and possible redescriptions is being emphasized.

The Carnivores of Quarry 3, Agate Fossil Beds National Monument

At the beginning of the twentieth century, in the remote upper reaches of the Niobrara River valley, paleontologists discovered an unbelievable trove of fossil bones eroding from two adjacent hillsides. Under these two “fossil hills” were buried entire skeletons of extinct animals that previously had been known only by fragmentary remains. Over the next two decades, leading museums of the day expended great effort exposing and then extracting whole portions of this bonebed for public exhibition and for research purposes. Many years later, scientists from the University of Nebraska–Lincoln reopened the old quarries to search for clues, long overlooked, that might explain why rhinoceroses, chalicotheres, and entelodonts had perished together millions of years ago at this particular place. In the process, they uncovered carnivore dens unrecognized by the first excavators. Today, the displays at Agate Fossil Beds National Monument lead visitors through the forensic evidence that discloses a sequence of events culminating in the demise of many hundreds of animals. The exhibits at the visitor center also include murals by artist Mark Marcuson and a diorama that uses full skeletal mounts, all illustrating the fascinating story of the Agate bonebed. In addition, the park is situated in a 3,000-acre preserve of shortgrass prairie and tells the story of rancher James Cook, who first noticed the bones in the 1880s, and his friendship with the scientists who came to excavate at Agate. Visitors can follow several trails to view the historic fossil sites, where wayside exhibits explain the paleontological investigations, and reconstruct the landscape of a dryland paleoriver valley and its animals, 22 million to 23 million years ago.

Fossil Finds Around Ancient Troy

Greek myths mention the existence of a monster (ketos) arount the city of Troy. This monster was killed by Heracles at cape Agammia (now Kucuk Besire Burun). There is a scene on a Greek vase dated to the sixth century, which depicts the heroic deed of Heracles at Agammia. The head of the monster is unmistakably a large animal fossil skull. In our survey project around Troy, we found fossil beds in in Beşige Burun, which most likey is the source of Greek myths concerning the Monster of Troy. Keywords : Troy, Fossill, Agammia, Kucuk Besige, Kumburun DOI : 10.7176/JSTR/5-2-25

Aptian carbonate platform development in the Southern Iberian Palaeomargin (Prebetic of Alicante, SE Spain)

The Aptian stratigraphic record of the Alicante region consists of: a rudist and coral-rich carbonate platform of earliest Aptian age (Llopis Formation), with a discontinuous siliciclastic member at its top; followed by late Early, to Late Aptian hemipelagic marls and marlstones (Almadich Formation); and then by renewed carbonate platform development of Late Aptian to earliest Albian age (Seguilí Formation). In the Llopis Formation, SW-dipping, massive clinoform beds of bioclastic debris are succeeded by flat-lying platform-top beds. The latter show a cyclically regressive stacking of biofacies, with rudist-dominated floatstone in their lower parts passing upwards to finer-grained, more sparsely fossiliferous bed tops with burrow mottling. Caprinid rudists, with originally almost wholly aragonitic shells, dominate the external platform-top facies, while more internal facies contain a mix of monopleurid, polyconitid and requieniid rudists, all with relatively slightly thicker development of the calcitic outer shell layer, together with caprinids. Biostratigraphic and carbon-isotope data link the termination of the Llopis platform with the onset of OAE1a. The carbonate platform of the Seguilí Formation again contains tabular platform-top beds showing repeated cyclic regression, with dense rudist and/or chondrodont floatstones overlain by sparser floatstones with wackestone matrix and secondarily filled burrows. But caprinids are now absent, while requieniids and polyconitids, some of large size, as well as radiolitids, all with thickened calcitic outer shell layers, accompany the tubular monopleurid, Mathesia, together with a greater development of Chondrodonta biofacies. The same overall pattern of biotic turnover from the Early, to the Late Aptian is confirmed in other parts of Iberia and contiguous regions. Moreover, Iberian platforms of late Early Aptian age outside the present study area reveal a transitional phase with an increasing proportion of polyconitids in the outer platform-top to upper slope facies at the expense of caprinids. The siliciclastic influx at the top of the Llopis Formation implies a climatic shift from arid, to relatively more humid/pluvial conditions through the mid-Early Aptian, as seen in several other Iberian sections. This climatic change was probably forced by the intensified greenhouse conditions at the onset of OAE1a. By contrast with these Iberian platforms, caprinids continued to dominate the outer platform-top zones of some central to southern Tethyan platforms until the close of the Early Aptian. This broad palaeolatitudinal differentiation of rudist associations within the Tethyan belt implies a climatic influence, whether exerted through thermal modulation of seawater pH and/or aragonite saturation, variation in nutrient flux, or any combination of these.

A micro X-ray computed tomography dataset of fossil echinoderms in an ancient obrution bed: a robust method for taphonomic and palaeoecologic analyses

BackgroundTaphonomic and palaeoecologic studies of obrution beds often employ conventional methods of investigation such as physical removal and extraction of fossils from their host rock (matrix) by mechanical preparation. This often-destructive method is not suitable for studying mold fossils, which are voids left in host rocks due to dissolution of the original organism in post-depositional processes.FindingsMicrocomputed tomography (µCT) scan data of 24 fossiliferous rock samples revealed thousands of Paleozoic echinoderms. Digitally "stitching" together individually µCT scanned rock samples within three-dimensional (3D) space allows for quantifiable taphonomic data on a fossil echinoderm-rich obrution deposit from the Devonian (Emsian) of South Africa. Here, we provide a brief step-by-step guide on creating, segmenting, and ultimately combining sections of richly fossiliferous beds to create virtual models suited for the quantitative and qualitative taphonomic analyses of fossil invertebrate assemblages.ConclusionsVisualizing the internal features of fossiliferous beds in 3D is an invaluable taphonomic tool for analyzing delicate fossils, accounting for all specimens irrespective of their preservation stages and with minimal damage. This technique is particularly useful for analyzing fossiliferous deposits with mold fossils that prove to be difficult to study with traditional methods, because the method relies on the large density contrast between the mold and host rock.

Detrital zircon U–Pb geochronology constrains the age of Brazilian Neogene deposits from Western Amazonia

The fossiliferous beds of the Solimões Formation, western Brazilian Amazon have yielded several vertebrate fossils that are key to understand the evolution of Neotropical biotas. Although this sedimentary unit has been studied for more than two centuries, no absolute dates are available so far, preventing more precise bio/chronostratigraphic interpretations and broader comprehension of the biotic/geological events that affected this northern portion of South America during the Neogene. Here, we present the first Neogene radioisotopic dates for the Brazilian Amazon, via U-Pb dating of detrital zircon from two classical sites. Both samples have small proportions of relatively young zircon grains, the dates from which are the maximum ages of deposition. LA-ICPMS analysis of two grains from the Niterói locality yielded a weighted mean of 8.5 ± 0.5 Ma and CA-TIMS analysis of two grains from the Talismã locality yielded a weighted mean of 10.89 ± 0.13 Ma. These maximum deposition ages are in the Tortonian stage, late Miocene, confirming the age previously inferred based on biochronological data.

First U-Pb zircon ages for late Miocene Ashfall Konservat-Lagerstätte and Grove Lake ashes from eastern Great Plains, USA.

This paper documents the first U-Pb zircon ages for Ashfall Fossil Beds (Nebraska, USA), a terrestrial Konservat-Lagerstätte mass-death assemblage that is arguably the most diverse of its type and age. The Ashfall tephra was correlated with ignimbrites from the Bruneau-Jarbidge volcanic field (12.7–10.5 Ma) in southwest Idaho based on geochemical analysis. The methods and geochemical data supporting the original age assessment of the ash bed, however, were never published, and there has been a persistent misconception that dateable heavy minerals (e.g., zircon) are absent. Notwithstanding, we recovered abundant zircons from Ashfall Fossil Beds, and from an ash bed ~6 km to the southeast at Grove Lake, Nebraska, and analyzed them through LA-ICP-MS. Our new zircon U-Pb age of 11.86 ± 0.13 Ma substantiates correlation of the Ashfall Fossil Beds deposit to tuffs originating from the Bruneau-Jarbidge caldera (~12.7–10.5 Ma). Our U-Pb zircon age of 6.42 ± 0.06 Ma for the Grove Lake ash bed coincides with supervolcanic activity in the Heise volcanic field (6.6–4.3 Ma) in eastern Idaho. These new dates improve age constraints of strata comprising the Ogallala Group and the important paleontological site. Moreover, we find that detrital and airfall zircons are unevenly distributed in the stratified ash beds we describe herein and presumably in similar deposits worldwide. Therefore, a higher-resolution sampling scheme is necessary in such cases.

Culcita remberi sp. nov., an Understory Fern of Cyatheales from the Miocene of Northern Idaho

Premise of research. Excavations at the Clarkia fossil beds in northern Idaho have recovered numerous exceptionally well-preserved plant fossils over the past 45 years. We report on a compression fossil of a fertile frond from a tree fern found at the Emerald Creek locality.Methodology. Intact leaf material was liberated from the substrate by wetting with hydrofluoric acid followed by submersion in a water bath. The lamina was preserved between sheets of acetate and photographed, and fertile pinnules with sporangia were mounted on aluminum stubs and imaged with scanning electron microscopy. Spores were released from sporangia after incubation in Schulz’s solution and treatment with KOH.Pivotal results. The specimen is similar to members of several extant fern lineages, including Hymenophyllaceae, Dennstaedtiaceae, and the tree fern order Cyatheales. It shares with these groups the possession of oblong, marginal sori, although the sori of the specimen are most similar to the cup-shaped sori of Dennstaedtiaceae and the bivalvate sori of Culcitaceae. The fossil also has sporangia, each with a complete, uninterrupted, oblique annulus, which is strongly associated with Culcitaceae.Conclusions. On the basis of its overall lamina morphology and details of the sori and especially the sporangia, we conclude that this specimen belongs to an extinct species of the monogeneric tree fern family Culcitaceae. The occurrence of a tree fern in the temperate plant community of the Miocene Clarkia locality is unexpected but not incompatible with the habitat preferences of this genus, as the two extant species of Culcita are found in montane altitudes and temperate forests elsewhere in the world.

Plant community ecology and climate on an upland volcanic landscape during the Early Eocene Climatic Optimum: McAbee Fossil Beds, British Columbia, Canada

The McAbee Fossil Beds, in south-central British Columbia, Canada, provide a record of forest ecosystems within a volcanically-active, upland landscape during the Early Eocene Climatic Optimum (EECO). To assess plant community ecology and climate within this environment, palynology and census-style macrofossil collections were investigated from two shale horizons separated in time by likely 103–104 years. An ensemble of leaf physiognomic estimates indicates a persistent warm (mean annual temperature [MAT] ≈ 10–12 °C) and mesic (mean annual precipitation ≈ 1000 mm∙yr−1) climate between the horizons. The plant community was similar in both horizons, comprising angiosperms (e.g., Ulmus, Fagus, Alnus, Betula, and Carya) and gymnosperms (e.g., Metasequoia, Pinus, Picea, and Larix). Plant diversity and the distribution of dicot leaf mass per area (MA) values were consistent between the two horizons, despite intervals of varying tuff thickness and frequency between the horizons. Differences in macrofossil abundances of Ulmus, Fagus, and Pinus, and a lack of such differences in their respective pollen abundances might be explained by local patch dynamics, influenced by spatial heterogeneity resulting from topographic diversity and disturbance. MA estimates suggest dicots were predominately deciduous, and the distribution of MA is similar to a modern forest in Panama influenced by seasonal precipitation. The diversity of dicots at McAbee, despite relatively lower mean annual temperatures, is comparable to fossil plant quarries of similar volume from early Eocene sites in Patagonia (e.g., Laguna del Hunco) and the Denver Basin with relatively warmer MATs (17–25 °C). This is best explained by a combination of predominately frost-free winters, high productivity, and an abiotic environment characterized by spatial heterogeneity and high rates of change. The sampled paleofloras of this study showcase an EECO plant community, likely representing an ecological solution to volcanic disturbance over millennial time scales.

Biostratigraphy and floristic evolution of coal swamp floras of a part of Talcher Basin, India: a window on a Permian temperate ecosystem

The present megafloral assemblage recorded from the Barakar sediments of Dholpahar section along Singda rivulet near Gopal Prasad Village in Talcher Basin comprises of equisetaceous stems, Gangamopteris buriadica, Palaeovittaria kurzii and 19 species of the genus Glossopteris. Record of Gangamopteris, Palaeovittaria and many narrow mesh forms of Glosspteris viz., G. angustifolia, G. churiensis, G. communis, G. recurva, G. spatulata, G. stenoneura, G. tenuifolia, G. vulgaris and G. zeilleri from two older fossiliferous horizons demonstrates that these fossils were preserved during Lower Barakar sedimentation. The report of middle and broad mesh forms of Glossopteris viz., G. barakarensis, G. browniana, G. indica, G. intermittens, G. karharbariensis, G. nakkarea, G. oldhamii, G. taeniensis and G. retifera in the youngest fossiliferous horizons reveals that these fossils were preserved during the deposition of Upper Barakar sediments. The continuation of some of the Karharbari plant fossils in the early phase of Barakar Formation and their disappearance in the flora of Late Barakar suggests a shift in the climatic setup. Palaeoclimate and palaeovegetation of this area are also summarised in this study. Moreover, the fossil assemblages of different fossiliferous beds of Dholpahar section demonstrate the evolution of midrib and meshes in different reticulate leaves.

Belowground rhizomes and roots in waterlogged paleosols: Examples from the Middle Jurassic of Beijing, China

Plant rhizomes and roots occur in terrestrial ecosystems since at least the Devonian, but the documentation of belowground plant tissues is sparse in the fossil record. In this study, fossils representing belowground rhizomes and roots are described from the top of the Upper Yaopo Formation (Middle Jurassic), at the Yuejiapo section, Mentougou District, Beijing, China. Morphological studies of the plant fossils, together with lithofacies analyses, provide new information on plant–soil interactions during the Jurassic period. Three types of rooting systems are recognized from two fossiliferous beds. The Bed-1 Flora is interpreted as representing a Cladophlebis-dominated community, where abundant foliage remains mainly of Cladophlebis cf. scariosa and Cladophlebis delicatula are associated with Type-A rooting system. The Bed-2 Flora includes Type-B and Type-C rooting systems, although the floristic composition is unknown due to the absence of identifiable foliage remains. The Type-A and Type-B rooting systems consist of abundant in situ vertical rhizomes, fine shoot-borne roots and lateral roots, and are consistent with those of some extant ferns. The Type-C rooting system shows a thick central taproot and at least three orders of lateral roots, an architecture typical of various gymnosperms. The in situ rooting systems, as well as sedimentary evidence, contribute to the recognition of stacked, reworked Entisols in a dynamic waterlogged environment.