Swedish Museum of Natural History
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Fish otoliths from the middle Paleocene (Selandian) of southern Sweden
No full textThe first fossil otolith association from the middle Paleocene (Selandian) of Scania, southern Sweden is described. Forty-seven otoliths were retrieved from shallow wells representing 14 teleost taxa. Many specimens are small and/or eroded and, therefore, not identifiable to species level. Nevertheless, our findings indicate the potential for further fossil otolith discoveries in the region. The Scanian otolith-based fauna greatly resembles the better-known coeval association from Copenhagen, Denmark, but is relatively rich and diverse in perciform otoliths. The fauna records the first occurrence of Serranus? caribbaeus from the European Paleocene, and of Archaemacruroides ornatus from the Selandian of the North Sea Basin
Searching for a nearest living equivalent for Bennettitales: a promising extinct plant group for stomatal proxy reconstructions of Mesozoic pCO2
No full textTo understand Earth ́s climate variability and improve predictions of future climate change, studying past climates is an important avenue to explore. A previously published record of pCO2, across the Triassic–Jurassic boundary (TJB, ~201 Ma) of East Greenland, showed that Bennettitales (Anamozamites and Pterophyllum) responded in parallel to the empirically proven pCO2-responders Ginkgoales, reducing their stomatal densities by half across the TJB, indicating a transient doubling of pCO2. The abundance of fossil Bennettitales in Mesozoic strata and natural history museum collections worldwide offers enormous potential for further stomatal proxy pCO2 reconstructions, but a suitable nearest living equivalent (NLE) should ideally first be identified for this extinct plant group. Using specimens from herbarium collections, three species of cycads, historically considered the best NLE, were tested for pCO2 response, as well as two species of tree ferns, grown in experimental growth chambers. None responded to changes in pCO2, and were consequently rejected as NLEs. Finally, two species of ferns were selected from the literature, and produced very similar pCO2 compared to Ginkgoales. However, these understory ferns are not appropriate NLEs for Bennettitales due to differences in habitat and a distant evolutionary relationship. Future work should test additional plant groups, in particular seed plants such as basal angiosperms and Gnetales, for suitability as NLE for Bennettitales in pCO2 reconstructions, for example through biogeo- chemical fingerprinting using infrared microspectroscopy. Until an appropriate NLE is identified, Bennettitales pCO2 can be reconstructed based on cross-calibration of stomatal densities with those of co-occurring pCO2 responders, such as Ginkgoales.This work was supported by the EU Marie Curie Excellence Grant (MEXT-CT-2006-042531) to J.McE and M.S., the Swedish Research Council (VR Starting Grant NT-7 2016 04905) to M.S., and the IRCSET Embark scholarship (R10679) to C.E-K. We also gratefully acknowledge funding from the EU Marie Curie Intra-European Fellowship (PEA-IEF-2010-275626) and ERC grant (ERC-279962-OXYEVOL). We thank the following for technical assistance: Bredagh Moran, UCD; Matthew Gilroy, Conviron UK; Aidan Blake, Aaron Refrigeration Ireland. </p
Biomechanical adaptations for burrowing in the incisor enamel microstructure of Geomyidae and Heteromyidae (Rodentia: Geomyoidea)
No full textThe enamel microstructure of fossil and extant Geomyoidea (Geomyidae, Heteromyidae) lower incisors incorporates three- or two-layered schmelzmusters with uniserial, transverse Hunter-Schreger bands having parallel and perpendicular or exclusively perpendicular oriented interprismatic matrix. Phylogenetically, these schmelzmusters are regarded as moderately (enamel type 2) to highly derived (enamel type 3). Our analysis detected a zone of modified radial enamel close to the enamel–dentine junction. Modified radial enamel shows a strong phylogenetic signal within the clade Geomorpha as it is restricted to fossil and extant Geomyoidea and absent in Heliscomyidae, Florentiamyidae, and Eomyidae. This character dates back to at least the early Oligocene (early Arikareean, 29 Ma), where it occurs in entoptychine gophers. We contend that this specialized incisor enamel architecture developed as a biomechanical adaptation to regular burrowing activities including chisel-tooth digging and a fiber-rich diet and was probably present in the common ancestor of the clade. We regard the occurrence of modified radial enamel in lower incisors of scratch-digging Geomyidae and Heteromyidae as the retention of a plesiomorphic character that is selectively neutral. The shared occurrence of modified radial enamel is a strong, genetically anchored argument for the close phylogenetic relationship of Geomyidae and Heteromyidae on the dental microstructure level
Phylogeny and taxonomic revision of the genus Craterispermum (Rubiaceae) in the Seychelles Archipelago
No full text The genus Craterispermum (Craterispermeae, Rubiaceae) is distributed in the tropical rain forests of Africa and Madagascar, with one morphologically variable species (Craterispermum microdon ) hitherto recognized in the Seychelles Archipelago. We conducted a Bayesian analysis of the combined ETS and ITS sequence data to: 1) test the monophyly of the Seychellois species of Craterispermum ; and 2) assess the phylogenetic relationships between the island populations. Our analyses supported the monophyly and, therefore, the single Malagasy origin of the Seychellois Craterispermum . The phylogenetic relationships between the three island populations were unresolved, since the Seychellois plants display a very low level of molecular variation. However, both herbarium and field studies revealed that the Craterispermum taxa occurring on the islands of Mahé, Praslin, and Silhouette, are morphologically distinct and geographically separated. As a result of these studies, two new species, Craterispermum praslinense and C. silhouettense , are described, to accommodate the Praslin and Silhouette populations, respectively, and C. microdon is restricted to the population on Mahé Island. A new taxonomic account for the Seychellois Craterispermum , and an identification key to the three species present in the archipelago, are provided. A provisional conservation status of each species, according to the IUCN Categories and Criteria, is presented
Restudy of some plectronocerid nautiloids (Cephalopoda) from the late Cambrian of China; discussion on nautiloid evolution and origin of the siphuncle
No full textThe sub-class Nautiloidea is divided into two super-orders, Nautilosiphonata and Calciosiphonata, basedon different structural types of the connecting rings.The late Cambrian order Plectronocerida has the calciosiphonate type of connecting ring similar tothat in post-Cambrian orthocerids. It is structurally more complex than the nautilosiphonate connectingring in late Cambrian ellesemerocerid-like nautiloids. The plectronocerid nautiloids, therefore, evolvedfrom the ellesmerocerid-like nautiloids and not vice versa. As indicated by the complex siphuncularstructure in plectronocerids, cephalopod evolution began earlier than previously estimated, probably inthe early Cambrian. The siphuncle in cephalopods originated from a calcareous septum that becamepartially non-calcified and formed the connecting ring
Hälso- och sjukdomsövervakning av marina däggdjur Del 2. Hälsa, sjukdomar och dödsorsaker hos tumlare (Phocoena phocoena) i Sverige de senaste 10 åren
No full textNomenclature of the magnetoplumbite group
No full textA nomenclature classification scheme has been approved by IMA-CNMNC for the magnetoplumbite group, with the general formula A[B12]O19. The classification on the highest hierarchical level is decided by the dominant metal at the 12-coordinated A sites, at present leading to the magnetoplumbite (A = Pb), hawthorneite (A = Ba) and hibonite (A = Ca) subgroups. Two species remain ungrouped. Most cations, with valencies from 2+ to 5+, show strong order over the five crystallographic B sites present in the crystal structure, which forms the basis for the definition of different mineral species. A new name, chihuahuaite, is introduced and replaces hibonite-(Fe)
Marine and terrestrial invertebrate borings and fungal damage in Paleogene fossil woods from Seymour Island, Antarctica
No full textAn assemblage of permineralized conifer and angiosperm woods collected from Paleogene marine strataon Seymour Island during the Swedish Antarctic expedition of 1901–1903 includes many specimens with internal damage caused by an array of xylophagous organisms. Short, broad, clavate borings referable to Gastrochaenolites clavatus are attributed to pholadid bivalves. Elongate borings with carbonate linings referable to Apectoichnus longissimus were produced by teredinid bivalves. Slender, cylindrical tunnels cross-cutting growth rings and backfilled in meniscoid fashion by frass composed of angular tracheid fragments were probably produced by a terrestrial beetle borer. They are most similar to tunnels generated by modern cerambycid and ptinid coleopterans. Less regular, spindle-shaped cavities and degraded zones flanking growth rings are similar to fungi-generated modern white pocket rot. Larger chambers in the heartwood referable to the ichnotaxon Asthenopodichnium lignorum were produced by an alternative mode of fungal degradation. The biological interactions evident in the fossil woods illustrate additional terrestrial trophic levels enhancing the known complexity of ecosystems on and around the Antarctic Peninsula shortly before the initial pulse of mid-Cenozoic glaciation in Antarctica that caused extirpation of the majority of plants and animals in that region
Discovering the world of fossil fungi
No full textWhen people think of fossils, they usually picture slabs of rock bristling with bones, or the shells of ammonites or trilobites. Most do not even consider that delicate organisms, such as fungi or bacteria, can even fossilize – they seem too fragile to be preserved as they lack a hard skeleton. In many cases this is true. Microscopic organisms that lack hard parts have fewer chances of being fossilised but, despite the odds, delicate fungi have a fossil record that is more extensive than generally thought