Primitive Member Research Articles

Multidomain truncated hemoglobins: New members of the globin family exhibiting tandem repeats of globin units and domain fusion.

Truncated hemoglobins (trHbs) are considered the most primitive members of globin superfamily and traditionally exist as a single domain heme protein in three distinct structural organizations, type I (trHb1_N), type II (trHb2_O) and type III (trHb3_P). Our search of microbial and lower eukaryotic genomes revealed a broad array of multidomain organization, representing multiunit and chimeric forms of trHbs, where multiple units of trHbs are joined together and/or integrated with distinct functional domains. Globin motifs of these multidomain trHbs were from all three groups of trHbs and unambiguously assigned to trHb1_N, trHb2_O and trHb3_P. Multiunit and chimeric forms of trHb1_N were identified exclusively in ciliated protozoan parasites, where multiple units of trHb are integrated in tandem and/or fused with another redox active or signalling domain, presenting an interesting example of gene duplication and fusion in lower eukaryotes. In contrast, trHb2_O and trHb3_P trHbs were found only in bacteria in two or multidomain organization, where amino or carboxy terminus of trHb unit is integrated with different redox-active or oxidoreductase domains. The identification of these new multiunit and chimeric trHbs and their specific phyletic distribution presents an interesting and challenging finding to explore and understand complex functionalities of these novel multidomain trHbs. © 2017 IUBMB Life, 69(7):479-488, 2017.

Origin of EL3 chondrites: Evidence for variable C/O ratios during their course of formation—A state of the art scrutiny

AbstractMineral inventories of enstatite chondrites; (EH and EL) are strictly dictated by combined parameters mainly very low dual oxygen (fO2) and sulfur (fS2) fugacities. They are best preserved in the Almahata Sitta MS‐17, MS‐177 fragments, and the ALHA 77295 and MAC 88136 Antarctic meteorites. These conditions induce a stark change of the geochemical behavior of nominally lithophile elements to chalcophile or even siderophile and changes in the elemental partitioning thus leading to formation of unusual mineral assemblages with high abundance of exotic sulfide species and enrichment in the metallic alloys, for example, silicides and phosphides. Origin and mode of formation of these exotic chondrites, and their parental source regions could be best scrutinized by multitask research experiments of the most primitive members covering mineralogical, petrological, cosmochemical, and indispensably short‐lived isotopic chronology. The magnitude of temperature and pressure prevailed during their formation in their source regions could eventually be reasonably estimated: pre‐ and postaccretionary could eventually be deduced. The dual low fugacities are regulated by the carbon to oxygen ratios estimated to be >0.83 and <1.03. These parameters not only induce unusual geochemical behavior of the elements inverting many nominally lithophile elements to chalcophile or even siderophile or anthracophile. Structure and mineral inventories in EL3 and EH3 chondrites are fundamentally different. Yet EH3 and EL3 members store crucial information relevant to eventual source regions and importantly possible variation in C/O ratio in the course of their evolution. EL3 and EH3 chondrites contain trichotomous lithologies (1) chondrules and their fragments, (2) polygonal enstatite‐dominated objects, and (3) multiphase metal‐rich nodules. Mineralogical and cosmochemical inventories of lithologies in the same EL3 indicate not only similarities (REE inventory and anomalies in oldhamite) but also distinct differences (sinoite‐enstatite‐graphite relationship). Oldhamite in chondrules and polygonal fragments in EL3 depict negative Eu anomaly attesting a common cosmochemical source. Metal‐dominated nodules in both EL3 and EH3 are conglomerates of metal clasts and sulfide fragments in EH3 and concentrically zoned C‐bearing metal micropebbles (≥25 μm ≤50 μm) in EL3 thus manifesting a frozen in unique primordial accretionary metal texture and composition. Sinoite‐enstatite‐diopside‐graphite textures reveal a nucleation and growth strongly suggestive of fluctuating C/O ratio during their nucleation and growth in the source regions. Mineral inventories, sulfide phase relations, sinoite‐enstatite‐graphite intergrowth, carbon and nitrogen isotopic compositions of graphite, spatial nitrogen abundance in graphite in metal nodules, and last but not least 129I/129Xe and 53Mn/53Cr systematics negate any previously suggested melting episode, pre‐accretionary or dynamic, in parental asteroids.

Dental topographic analysis of paromomyid (Plesiadapiformes, Primates) cheek teeth: more than 15 million years of changing surfaces and shifting ecologies

Plesiadapiforms, appearing near the Cretaceous-Paleogene boundary, represent the first primate radiation and show a diverse array of tooth morphologies. Dental topographic metrics provide quantitative data on occlusal surface shape. We used three metrics, Dirichlet Normal Energy, Relief Index, and 3D Orientation Patch Count Rotated, to assess changes in the morphology of lower fourth premolars and lower second molars in a taxonomically broad sample of one family of plesiadapiforms, Paromomyidae, stretching more than 15 million years. Our results indicate that paromomyids occupied a more diverse range of dietary categories than suspected. Whereas all paromomyids were likely omnivores, some species show higher levels of insectivory, while other taxa are inferred to have been mixed-feeding omnivores with high levels of fruit intake. The results also show that the more primitive members of the different paromomyid lineages were more insectivorous than the derived and more recent members of those lineages. Relief Index values also show taxonomic signals that are consistent with ancestor-descendant relationships hypothesised for species of Phenacolemur. These results suggest that dental topographic metrics are informative to the study of paromomyids for both dietary categorisation and for the distinction of species at a fine taxonomic level.

Geochemistry of the Palaeoproterozoic volcanic and associated potassic granitic rocks of the Ngualla area of the Ubendian Belt, SW Tanzania

The Ngualla area of the Lupa terrane in the Ubendian Belt of SW Tanzania is underlain by well-preserved greenschist facies calc-alkaline volcanic rocks which have been intruded by low-Sr, peraluminous K-rich granites. The Ngualla volcanic rocks are subdivided into four groups: the basaltic andesites-trachyandesites, Group I porphyritic dacites-trachytes, Group II porphyritic dacites-trachytes, and rhyolites. The basaltic andesites-trachyandesites were emplaced at ∼1943 Ma and their most primitive members are characterized by MgO contents of up to 7.43 wt % at a SiO2 content of 54.0 wt %, Ni contents of up to 170 ppm and Mg# of up to 62. They show fractionated REE patterns (La/YbCN = 11.5–36.5), sub-chondritic Zr/Hf (37.8–43.9) and Nb/Ta (7.14–20.0) ratios, εNd (1943 Ma) values of −3.33 to −6.24 and TDM ages of 2521–2883 Ma. These geochemical features are consistent with derivation of the basaltic andesites-trachyandesites by at least 0.1% partial melting of garnet peridotite mantle, followed by 50–80% fractional crystallization involving the removal of 61% clinopyroxene, 20% hornblende, 4% plagioclase and 15% orthopyroxene. The magmas were contaminated by Neoarchaean crustal materials incorporated in the Ubendian Belt during their ascent to the surface. The evolution of these magmas led to the formation of Group I porphyritic dacites-trachytes and rhyolites in a Palaeoproterozoic continental arc setting.The Group II porphyritic dacites-trachytes (1871 ± 5 Ma) were coevally emplaced with the low-Sr, peraluminous K-granites (1878 ± 15 Ma) forming a felsic plutonic-volcanic suite. Despite some differences, these rocks share geochemical features including negative Eu anomalies (mean Eu/Eu* = 0.19 for the dacites and 0.5 for the granites) and εNd (1871 Ma) values of −5.72 for the dacites and εNd (1878 Ma) values of −6.00 to −11.2 for the granites. These geochemical features are consistent with the generation of the ∼1.87 Ga Ngualla felsic plutonic-volcanic suite by partial melting of heterogeneous Neoarchaean crust at low pressure conditions in the stability field of plagioclase in an intracontinental setting along a sutured margin.The 1.89–1.87 Ga felsic plutonic-volcanic suite also occurs in the Ndembera area of the Usagaran belt to the SW. Our results corroborate previous evidence that the Palaeoproterozoic regional K-granitic magmatism that affected parts of the Ubendian and Usagaran belts was caused by a regional thermal anomaly that was induced by large scale magmatic underplating that precipitated widespread crustal anatexis.

Unique Bacteria Community Composition and Co-occurrence in the Milk of Different Ruminants

Lactation provides the singular source of nourishment to the offspring of mammals. This nutrition source also contains a diverse microbiota affecting the development and health of the newborn. Here, we examined the milk microbiota in water deer (Hydropotes inermis, the most primitive member of the family Cervidae), reindeer (Rangifer tarandus, the oldest semi-domesticated cervid), and the dairy goat (Capra aegagrus, member of the family Bovidae), to determine if common milk microbiota species were present across all three ruminant species. The results showed that water deer had the highest bacterial diversity, followed by reindeer, and then goat. Unifrac distance and correspondence analyses revealed that water deer harbored an increased abundance of Pseudomonas spp. and Acinetobacter spp., while milk from reindeer and goat was dominated by unclassified bacteria from the family Hyphomicrobiaceae and Bacillus spp., respectively. These data indicate significant differences in the composition of milk-based bacterial communities. The presence of Halomonas spp. in three distinct co-occurrence networks of bacterial interactions revealed both common and unique features in milk niches. These results suggest that the milk of water deer and reindeer harbor unique bacterial communities compared with the goat, which might reflect host microbial adaptation caused by evolution.

A new species of the genusCoccidohystrix(Homoptera: Coccinea: Pseudococcidae) from Madagascar

Coccidohystrix primigenia n. sp. is described and illustrated. The new species is considered as a most primitive member of the genus in the recent fauna. An identification key for all 17 nominal species of the genus is provided. http://zoobank.org/urn:lsid:zoobank.org:pub:BC2F3B54-AB5F-49E3-9998-E34A8E09D034

Evidence for underplating in the genesis of the Variscan synorogenic Beja Layered Gabbroic Sequence (Portugal) and related mesocratic rocks

The Beja Layered Gabbroic Sequence (LGS) is a mafic, layered synorogenic intrusion that was emplaced at the SW border of the Ossa Morena Zone (OMZ) at ca. 350Ma during the early stages of the Variscan oblique continental collision. The LGS represents the primitive member of the Beja Igneous Complex (BIC), which records part of an important Variscan magmatic event to the north of the SW Iberian suture that led to the formation of several igneous complexes. Although LGS primary magmatic features are well-preserved from post-crystallization tectono-metamorphic events, the magma chamber processes were influenced by the Variscan regional stress field which affected also the development of the magmatic layering and associated foliation.The baric evolution recorded in LGS (from 9 to 4kbar) is compatible with early crustal underplating of juvenile basaltic magma at the Moho. Mild lower crustal contamination resulted in Nb-Ta-Rb-Th depletion and higher REE fractionation compared to MORB. Contamination proceeded mainly by assimilation-fractional-crystallization (AFC) at final level of emplacement.The obtained results suggest that the spatially associated BIC mesocratic rocks are genetically related to LGS, both deriving from an equivalent mantle source. It is proposed that the underplating of basaltic magmas at the lower crust gave rise to a deep crustal hot zone. This allows BIC evolution to be explained as a single, long-lived magmatic event of progressive geochemical and lithological diversification due to the involvement of distinct crustal components. The most important components were incorporated at depth by the reworking of OMZ lower crustal rocks, with the involvement of middle crustal rocks later on, and of upper crustal contamination during the final stages of emplacement.

Middle Eocene rodents from Sant Jaume de Frontanyà (eastern Pyrenees, northern Spain) and biochronological implications

ABSTRACTThe locality of Sant Jaume de Frontanyà (Eastern Pyrenees, Catalonia, northeastern Spain) includes four fossil-bearing levels with an extraordinary abundance of mammal remains, representing the most significant middle Eocene site from the Iberian Peninsula. Despite this, the fauna from this locality has not been studied in detail. Recent work has mostly focused on the primates from the oldest levels, including the description of two new species, Anchomomys frontanyensis and Pseudoloris pyrenaicus. Recently, study of the primate remains from the uppermost level, Sant Jaume de Frontanyà-1 (SJF-1), has led to the description of a new species of Necrolemur. On the other hand, other mammal groups such as rodents are practically undescribed. In this work, rodent remains from SJF-1 are described for the first time. Three different forms have been identified: one glirid, referred to Glamys aff. robiacensis, and two theridomyids that have allowed the erection of the new species Paradelomys santjaumensis and Elfomys catalaunicus, suggested to be the most primitive members of the genera Paradelomys and Elfomys. These three forms show more primitive traits than other species from upper Bartonian (MP16) localities such as Robiac, Grisolles, and Le Bretou. Locality SJF-1 is therefore assigned to the lower Bartonian (MP15), with an age slightly older than Chéry-Chartreuve, and represents the first occurrence of the genera Paradelomys and Elfomys. Moreover, this dating allows us to place the only record of Necrolemur from the Iberian Peninsula in a correct chronological framework, shedding new light on the evolution of this primate genus.http://zoobank.org/urn:lsid:zoobank.org:pub:3609A71E-9414-4935-BD58-BE7812C49497Citation for this article: Bonilla-Salomón, I., R. Minwer-Barakat, M. Vianey-Liaud, and S. Moyà-Solà. 2016. Middle Eocene rodents from Sant Jaume de Frontanyà (eastern Pyrenees, northern Spain) and biochronological implications. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1121

New geological and palaeontological age constraint for the gorilla-human lineage split.

The palaeobiological record of 12 million to 7 million years ago (Ma) is crucial to the elucidation of African ape and human origins, but few fossil assemblages of this period have been reported from sub-Saharan Africa. Since the 1970s, the Chorora Formation, Ethiopia, has been widely considered to contain ~10.5 million year (Myr) old mammalian fossils. More recently, Chororapithecus abyssinicus, a probable primitive member of the gorilla clade, was discovered from the formation. Here we report new field observations and geochemical, magnetostratigraphic and radioisotopic results that securely place the Chorora Formation sediments to between ~9 and ~7 Ma. The C. abyssinicus fossils are ~8.0 Myr old, forming a revised age constraint of the human-gorilla split. Other Chorora fossils range in age from ~8.5 to 7 Ma and comprise the first sub-Saharan mammalian assemblage that spans this period. These fossils suggest indigenous African evolution of multiple mammalian lineages/groups between 10 and 7 Ma, including a possible ancestral-descendent relationship between the ~9.8 Myr old Nakalipithecus nakayamai and C. abyssinicus. The new chronology and fossils suggest that faunal provinciality between eastern Africa and Eurasia had intensified by ~9 Ma, with decreased faunal interchange thereafter. The Chorora evidence supports the hypothesis of in situ African evolution of the Gorilla-Pan-human clade, and is concordant with the deeper divergence estimates of humans and great apes based on lower mutation rates of ~0.5 × 10(-9) per site per year (refs 13 - 15).

Geochemistry of the metavolcanic rocks from the Çangaldağ Complex in the Central Pontides: implications for the Middle Jurassic arc-back-arc system in the Neotethyan Intra-Pontide Ocean

The Cangaldag Complex in northern central Turkey is one of the main tectonic units of the Central Pontide Structural Complex that represents the remains of the poorly known Intra-Pontide branch of the Neotethys. It comprises low-grade metamorphic rocks of intrusive, extrusive, and volcaniclastic origin displaying a wide range of felsic to mafic compositions. Petrographically the complex consists of basalts-andesites-rhyodacites and tuffs with minor amount of gabbros and diabases. On the basis of geochemistry, the Cangaldag samples are of subalkaline character and represented by both primitive and evolved members. All rock types are variably depleted in Nb compared to LREEs, similar to the lavas from subduction-related tectonic settings. In N-MORB normalized plots, the primitive members are separated into 3 groups on the basis of levels of enrichment. The first group is highly depleted and displays characteristics of boninitic lavas. The second group is relatively enriched compared to the first group but still more depleted than N-MORB. The third group, however, is the most enriched one among the three, whose level of enrichment is around that of N-MORB. The overall geochemical features suggest that the Cangaldag Complex has been generated with the involvement of a subduction-modified mantle source. The chemistry of the primitive members further indicates that the melts generated for the formation of the Cangaldag Complex probably occurred in both arc and back-arc regions above an intraoceanic subduction within the Intra-Pontide branch of the Neotethys.

Early Cretaceous palm pollen tetrads from Patagonia, Argentina

Pollen tetrads and monads of spiny pollen grains with close affinities to palms have been found in several localities from the Lower Cretaceous (Barremian-Albian) of the Austral Basin (Magallanes), Patagonia (Argentina). When found dispersed, spiny and zonasulcate pollen grains, are commonly referred to the fossil genus Spinizonocolpites Muller, with close affinities to the extant palm Nypa. The Patagonian specimens were compared with fossil and extant members of the Arecaceae, showing close similarities in shape and sculpture with the primitive members of the subfamily Calamoideae. Nypa produces tetragonal tetrads different from the tetrahedral tetrads of the Spinizonocolpites-type recovered from Patagonia. The specimens were studied with LM and SEM. The polarity, aperture orientation and tetrad type allow segregating the Patagonian grains from the Nypoideae and relating it to the Calamoideae subfamily. These records suggest an antique origin of monocots and a probably initial diversification of calamoid palms during the Early Cretaceous in high latitudes of Gondwana. The presence of palmae during the Early Cretaceous in southern South America suggests a warm and humid climate, similar to that found in present days at tropics.

Evolution of Protanancus (Proboscidea, Mammalia) in East Asia

ABSTRACT—Interspecific competition and species replacement explain many evolutionary successions, but these processes are difficult to test. According to recent paleontological research, amebelodontines were predominant proboscideans in faunas of the early to middle Miocene of East Asia. In addition to the abundant Platybelodon, other amebelodontines are known, but they have been largely neglected by researchers. Here we describe two species of Protanancus, Pr. tobieni and Pr. brevirostris, sp. nov., from China. The former was present during the middle Miocene in Tongxin and Qin’an and was previously attributed to Amebelodon or Serbelodon; the latter was present during the early Miocene in the Linxia Basin. Cladistic analysis indicates that the two species appear to represent primitive members of Protanancus. However, the phylogenetic relationship among Protanancus, Platybelodon, and Amebelodon remains unresolved because of their strong parallel evolution. Our study suggests intensive competition between Protanancus and Platybelodon based on similarities in their mandibular morphologies and dental microwear patterns, with the former genus disappearing from East Asia by the late middle Miocene. This scenario is supported by a mechanical model, in which lower tusks with dentinal tubules, as occur in Platybelodon, show greater resistance to the adverse effects of both a heavy load and abrasion than those with concentric laminae, present in Protanancus. The model aids in interpreting the evolution of the inner structure of the lower tusks of amebelodontines, which may have provided a competitive advantages for these species.http://zoobank.org/urn:lsid:zoobank.org:pub:4D33BD71-CB05-4058-B9DD-337060B0B7CBSUPPLEMENTAL DATA——Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

Decay of velvet worms (Onychophora), and bias in the fossil record of lobopodians.

BackgroundFossil lobopodians, including animals proposed to have close affinity to modern onychophorans, are crucial to understanding the evolution of the panarthropod body plan and the phylum-level relationships between the ecdysozoan groups. Unfortunately, the key features of their anatomy are un-mineralized and subject to biases introduced during death, decay and preservation, yet the extent to which these fossils have been affected by the processes of post-mortem decay is entirely untested. Recent experimental work on chordates has highlighted a profound bias caused by decay, resulting in the erroneous interpretation of badly decayed specimens as primitive members of a clade (stemward slippage). The degree to which this bias affects organisms other than chordates is unknown.ResultsHere we use experimental decay of velvet worms (Onychophora) to examine the importance of decay bias in fossil lobopodians. Although we find stemward slippage is not significant in the interpretation of non-mineralized lobopodian fossils, the affect of decay is far from unbiased. Quantitative analysis reveals significant changes in body proportions during decay, a spectrum of decay resistance across anatomical features, and correlated decay of topologically associated characters.ConclusionsThese results have significant implications for the interpretation of fossil lobopodian remains, demonstrating that features such as body outline and relative proportions are unreliable for taxonomy or phylogenetic reconstruction, unless decay is taken into account. Similarly, the non-independent loss of characters, due to juxtaposition in the body, during decay has the potential to bias phylogenetic analyses of non-biomineralized fossils. Our results are difficult to reconcile with interpretations of highly decay-prone tissues and structures, such as neural tissue, and complex musculature, in recently described Cambrian lobopodians. More broadly, we hypothesize that stemward slippage is unlikely to be a significant factor among the taphonomic biases that have affected organisms where decay-resistant features of the anatomy are rich in phylogenetically informative characters. Conversely, organisms which possess decay-resistant body parts but have informative characters concentrated in decay-prone tissues will be just as liable to bias as those that lack decay-resistant body parts. Further experimental analysis of decay is required to test these hypotheses.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-014-0222-z) contains supplementary material, which is available to authorized users.

On the “Coccodus” lindstroemi species complex (Pycnodontiformes, Gladiopycnodontidae) from the marine Late Cretaceous of Lebanon, with the description of two new genera

The osteology of “ Coccodus ” lindstroemi is studied in detail and it is demonstrated that this species does not belong to the genus Coccodus , but is a rather primitive member of the pycnodontiform family Gladiopycnodontidae. Indeed, the snout of “ Coccodus ” lindstroemi is elongated in a rostrum formed by the prefrontal and the premaxilla. This rostrum extends beyond the lower jaw level. The toothless premaxilla is sutured by its upper margin to the lower margin of the long and broad prefrontal. The pectoral fin is lost and replaced by a pectoral spine which articulates on the cleithrum. A long nuchal spine resting on the dermosupraoccipital is present. The body is entirely covered by scales that are flake-like in the abdominal region and scute-like in the caudal region. Joinvillichthys gen. nov. is thus erected with “ Coccodus ” lindstroemi as the type species. It is also shown that specimens with dumpier head and body, usually ranged in “ Coccodus ” lindstroemi , represent another species of the same genus for which the taxon Joinvillichthys kriweti gen. et sp. nov. is created. Specimens sometimes considered as possible juveniles of “ Coccodus ” lindstroemi form a distinctive new genus and species of gladiopycnodontid fish, Pankowskichthys libanicus gen. et sp. nov. Pankowskichthys differs from Joinvillichthys by many osteological structures.

High-resolution chronostratigraphy of the terrestrial Cretaceous-Paleogene transition and recovery interval in the Hell Creek region, Montana

Research Article| March 01, 2015 High-resolution chronostratigraphy of the terrestrial Cretaceous-Paleogene transition and recovery interval in the Hell Creek region, Montana Courtney J. Sprain; Courtney J. Sprain † 1Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA †E-mail: spra0111@berkeley.edu Search for other works by this author on: GSW Google Scholar Paul R. Renne; Paul R. Renne 1Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA2Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94720, USA Search for other works by this author on: GSW Google Scholar Gregory P. Wilson; Gregory P. Wilson 3Department of Biology, and Burke Museum of Natural History and Culture, University of Washington, Seattle, Washington 98195, USA Search for other works by this author on: GSW Google Scholar William A. Clemens William A. Clemens 4Department of Integrative Biology, University of California, Berkeley, California 94720, USA5Museum of Paleontology, University of California, Berkeley, California 94720, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2015) 127 (3-4): 393–409. https://doi.org/10.1130/B31076.1 Article history received: 02 Feb 2014 rev-recd: 24 Jun 2014 accepted: 12 Aug 2014 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Courtney J. Sprain, Paul R. Renne, Gregory P. Wilson, William A. Clemens; High-resolution chronostratigraphy of the terrestrial Cretaceous-Paleogene transition and recovery interval in the Hell Creek region, Montana. GSA Bulletin 2015;; 127 (3-4): 393–409. doi: https://doi.org/10.1130/B31076.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Detailed understanding of ecosystem decline and recovery attending the Cretaceous-Paleogene boundary (KPB) mass extinctions is hindered by limited constraints on the pace and tempo of environmental events near the boundary. To mitigate this shortcoming, high-resolution 40Ar/39Ar geochronology was performed on tephras intercalated between fossiliferous terrestrial sediments of the upper Hell Creek and lower Fort Union Formations in the western Williston Basin of northeastern Montana (USA). Tephra samples were collected from 10 stratigraphic sections spanning an area of ∼5000 km2. Several distinctive tephras can be correlated between sections separated spatially by as much as ∼60 km. The tephras are thin distal deposits generally preserved only in lignite beds, which are interbedded with clastic deposits yielding vertebrate faunas of Lancian (late Maastrichtian) to Torrejonian (early Danian) North American Land Mammal Ages. Sanidine from 15 tephra samples was analyzed in 1649 total fusion experiments (1597 on single crystals) and 12 incremental heating analyses of multigrain aliquots. Ages were determined for 13 distinct tephras, ranging from 66.289 ± 0.051 to 64.866 ± 0.023 Ma, including only analytical uncertainties. This level of precision is sufficient to resolve the ages of all of the coal beds that have served as a basis for a regional stratigraphic framework. The data confirm that the Hell Creek–Fort Union formational contact is diachronous, and further support the age of the KPB impact layer at 66.043 ± 0.010 Ma (or ± 0.043 Ma considering systematic uncertainties). Application of the new results to previous magnetostratigraphic data indicates an appreciably compressed time interval between the base of chron C29r and the top of chron C28r, with a maximum duration estimate of 1.421 ± 0.066 Ma. Most notable is the implied brevity of chron C29r, with a maximum estimate of 457 ± 54 ka, and possibly as brief as 345 ± 38 ka, compared to the 710 ka estimate from the Geologic Time Scale 2012 (GTS2012). Further, application of new results to terrestrial biostratigraphy adds higher precision to the timing and tempo of biotic change before and after the KPB. Our results indicate that the timing of pre-KPB ecological decline is constrained to the last ∼200 ka of the Cretaceous, adding further support to the press-pulse extinction hypothesis. Additionally, the duration of the depauperate basal Paleogene Puercan 1 disaster fauna is confined to a 70 ka interval. Faunal recovery in this region, indicated by the appearance of primitive members of the placental mammal radiation and the restoration of taxonomic richness and evenness, occurred within ∼900 ka after the KPB. These results show that biotic recovery after the mass extinction in the terrestrial realm was more rapid than in the marine. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

A New Carcharodontosauria (Theropoda) from the Early Cretaceous of Guangxi, Southern China

AbstractA new large‐bodied theropod dinosaur, Datanglong guangxiensis gen. et sp. nov., was recovered from the Lower Cretaceous Xinlong Formation of the Datang Basin, Guangxi. It is unique in several features including: posteriormost dorsal vertebra with teardrop‐shaped pneumatic foramen confined by enlarged pcdl, acpl and the centrum; posteriormost dorsal with well‐developed, horizontal prpl; posteriormost dorsal with a parapophysis projecting more laterally than the diapophysis; brevis fossa shallow with short, ridge‐like medial blade; and iliac pubic peduncle with posteroventrally expanded margin. Cladistic analysis supports the idea that this new taxon Datanglong guangxiensis is a primitive member of the Carcharodontosauria in possessing two unambiguous synapomorphies: large external pneumatic foramina and internal spaces present in the lateral surface of ilium, and a peg‐and‐socket ischiac articulation with the ilium. The presence of the new taxon from Guangxi further confirms that Carcharodontosauria were cosmopolitan large‐bodied predators during the Early‐mid Cretaceous.

Inflammatory effects of Edwardsiella ictaluri lipopolysaccharide modifications in catfish gut.

Bacterial lipopolysaccharides (LPS) are structural components of the outer membranes of Gram-negative bacteria and also are potent inducers of inflammation in mammals. Higher vertebrates are extremely sensitive to LPS, but lower vertebrates, like fish, are resistant to their systemic toxic effects. However, the effects of LPS on the fish intestinal mucosa remain unknown. Edwardsiella ictaluri is a primitive member of the Enterobacteriaceae family that causes enteric septicemia in channel catfish (Ictalurus punctatus). E. ictaluri infects and colonizes deep lymphoid tissues upon oral or immersion infection. Both gut and olfactory organs are the primary sites of invasion. At the systemic level, E. ictaluri pathogenesis is relatively well characterized, but our knowledge about E. ictaluri intestinal interaction is limited. Recently, we observed that E. ictaluri oligo-polysaccharide (O-PS) LPS mutants have differential effects on the intestinal epithelia of orally inoculated catfish. Here we evaluate the effects of E. ictaluri O-PS LPS mutants by using a novel catfish intestinal loop model and compare it to the rabbit ileal loop model inoculated with Salmonella enterica serovar Typhimurium LPS. We found evident differences in rabbit ileal loop and catfish ileal loop responses to E. ictaluri and S. Typhimurium LPS. We determined that catfish respond to E. ictaluri LPS but not to S. Typhimurium LPS. We also determined that E. ictaluri inhibits cytokine production and induces disruption of the intestinal fish epithelia in an O-PS-dependent fashion. The E. ictaluri wild type and ΔwibT LPS mutant caused intestinal tissue damage and inhibited proinflammatory cytokine synthesis, in contrast to E. ictaluri Δgne and Δugd LPS mutants. We concluded that the E. ictaluri O-PS subunits play a major role during pathogenesis, since they influence the recognition of the LPS by the intestinal mucosal immune system of the catfish. The LPS structure of E. ictaluri mutants is needed to understand the mechanism of interaction.

Abundances of presolar silicon carbide grains in primitive meteorites determined by NanoSIMS

It has been suggested that the matrices of all chondrites are dominated by a common material with Ivuna-like (CI) abundances of volatiles, presolar grains and insoluble organic matter (IOM) (e.g., Alexander, 2005). However, matrix-normalized abundances of presolar silicon carbide (SiC) grains estimated from their noble gas components show significant variations in even the most primitive chondrites (Huss and Lewis, 1995; Huss et al., 2003), in contradiction to there being a common chondrite matrix material. Here we report presolar SiC abundances determined by NanoSIMS raster ion imaging of IOM extracted from primitive members of different meteorite groups. We show that presolar SiC abundance determinations are comparable between NanoSIMS instruments located at three different institutes, between residues prepared by different demineralization techniques, and between microtomed and non-microtomed samples. Our derived SiC abundances in CR chondrites are comparable to those found in the CI chondrites (∼30ppm) and are much higher than previously determined by noble gas analyses. The revised higher CR SiC abundances are consistent with the CRs being amongst the most primitive chondrites in terms of the isotopic compositions and disordered nature of their organic matter. Similar abundances between CR1, CR2, and CR3 chondrites indicate aqueous alteration on the CR chondrite parent body has not progressively destroyed SiC grains in them. A low SiC abundance for the reduced CV3 RBT 04133 can be explained by parent body thermal metamorphism at an estimated temperature of ∼440°C. Minor differences between primitive members of other meteorite classes, which did not experience such high temperatures, may be explained by prolonged oxidation at lower temperatures under which SiC grains formed outer layers of SiO2 that were not thermodynamically stable, leading to progressive degassing/destruction of SiC.

Redescription of Limnosida frontosa Sars, 1862 (Crustacea: Cladocera: Sididae), with evidence of possible incipient species differentiation.

Limnosida frontosa Sars, 1862 is redescribed based on the material from over its entire range, from Norway and Finland in the west to Yakutia in eastern Siberia and the Lower Amur River basin (Far East of Russia) in the east. Morphological analysis of the species has revealed a combination of advanced and evolutionary primitive features, latter characterizing Limnosida as the most primitive member of the order Ctenopoda. Investigation of intra- and interpopulational morphological variability, in particular of the post abdominal claws, led to a tentative separation of the species into two main forms, occurring regionally in the north-west and east of Northern Eurasia. Their taxonomic status as yet remains unclear. Some overlap in geographical distribution of these forms and the presence of populations with intermediate morphological features probably reflects irregularity of the diversification process in L. frontosa s.l. within its range. This diversification may be the result of both geographic disjunction and adaptation to waters of different trophic status. The low level of intraspecies differentiation and comparatively limited geographic distribution of this species imply its young age while the genus Limnosida itself is presumed ancient.

Phenology and pollen studies of some species of Annonaceae in Nigeria

Phenology and pollen studies were investigated in some species of Annonaceae in Nigeria to help in providing pollen data and record of flowering patterns of the species studied. Phenological data for flowering and fruiting were tracked once a week for both rainy and dry seasons. Pollen grains from fresh anthers of the different species of Annonaceae were collected for pollen grain stainability and morphological studies. The peak flowering period in all the species studied was between March and April. Flower production took place before flushing of leaves in M. tenuifolia , however, in A. reticulata and A. squamosa , flowering and flushing of leaves occurred at the same time. All the species have predictable annual fruiting periods; the harvesting of their fruits and seeds, and sustainable management is bound to be relatively easy. The percentage pollen stainability was higher than percentage pollen germination in the species studied. Low fertility was observed in A. reticulata and C. patens . Tetrad pollen observed in Annona, Monodora and Xylopia is an advanced character in Annonaceae and could have an advantage over the monad. The genus Cleistopholis now appears to be one of those genera which have retained the largest number of the characteristics of a primitive member of Annonaceae. The evolutionary development is from Cleistopholis (monad) to Xylopia (tetrad) to Monodora (tetrad) to Annona (tetrad). Keywords : Phenology, Pollen, Annonaceae, Evolution, Monad, Tetrad.