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Lower–Middle Cambrian faunas and stratigraphy from northern Siberia
No full textNew assemblages of skeletal fossils chemically extracted from carbonates of the Cambrian Stage 2–Drumian Stage are reported from the lower reaches of the Lena River as well as from the Khorbusuonka, Malaya Kuonamka, and Bol’shaya Kuonamka rivers in northern part of the Siberian Platform. The fauna studied with scanning electron microscopy includes brachiopods, molluscs, hyoliths, halkieriids, chancelloriids, tommotiids, lobopodians, palaeoscolecidans, bradoriids, echinoderms, anabaritids, hyolithelminths, and sponges showing similarity to previously described fossil assemblages from Siberia, Laurentia, and Gondwana. The material includes emended descriptions of Halkieria proboscidea, Hadimopanella knappologica, Archaeopetasus typicus, and first descriptions of Hadimopanella foveata Kouchinsky sp. nov. and Archaeopetasus pachybasalis Kouchinsky sp. nov. Affinity of Archaeopetasus to chancelloriids is suggested. Finding of an in-place operculum in a planispiral shell of Michniakia minuta enables reinterpretation of this form as a hyolith, not a mollusc. The cambroclavids Cambroclavus sp. and Zhijinites clavus and the earliest echinoderms belonging to the Rhombifera and Ctenocystoidea are reported respectively from the lower Botoman stage and Botoman–Toyonian transitional beds, correlated with Cambrian Stage 4. Carbon isotopes are analysed from sections of the Chuskuna (upper Kessyusa Group), Erkeket, Kuonamka, Olenyok, Yunkyulyabit-Yuryakh, Tyuser and Sekten formations. A major part ofthe δ13C record is obtained from the Cambrian Stage 4–Drumian Stage strata which remain incompletely characterised by chemostratigraphy. The Lower Anomocarioides limbataeformis Carbon isotope Excursion (LACE) from the Drumian Stage of the Khorbusuonka River is introduced herein. New chemostratigraphic data are used for regional and global correlation and facilitate study of the evolutionary development of animals and faunas through the “Cambrian explosion”.Our field trips to Malaya Kuonamka and Bol’shaya Kuonamka riversin 1996 and to the Khorbusuonka and Lena rivers in 2000 were financially supported by grants to SB from the Royal Swedish Academy of Sciences and the Swedish Research Council. We thank Shane Pelechaty (Shell, Calgary, Canada) for collecting isotope samples from outcrops of the Malaya Kuonamka and Bol’shaya Kuonamka rivers in 1996, Stefan Ohlsson (Swedish Museum of Natural History, Stockholm, Sweden) and Klara Hajnal (Stockholm University, Sweden) for technical assistance with sample preparation and analyses. AK is grateful to Ilya Kuchinsky (International English School in Täby, Sweden) for assistance with SEM imaging. LH’s work was supported by a grant from the Swedish Research Council (VR 2018-03390). AZ’s study is carried out as a part of Scientific Project 04-1-21 of the State Order of the Government of the Russian Federation to the Lomonosov Moscow State University No. 121031600198-2. RW and FB are supported bya NERC Discovery Grant (NE/T008458/1). VP has been supported by the Kazan Federal University Strategic Academic Leadership Program.</p
Truly a hyperparasite, or simply an epibiont on a parasite? The case of Cyclocotyla bellones (Monogenea, Diclidophoridae)
No full textCyclocotyla bellones Otto, 1823 (Monogenea, Diclidophoridae) is one of the few monogenean species reported as hyperparasitic: the worms dwell on cymothoid isopods, themselves parasites of the buccal cavity of fishes. We present here observations based on newly collected monogenean specimens from Ceratothoa parallela (Otto, 1828), an isopod parasite of Boops boops off Algeria and also investigated its diet to address whether Cy. bellones is indeed a hyperparasite, i.e., whether it feeds on the isopod. We also compared the body shape of various monogeneans belonging to the same family as Cy. bellones, the Diclidophoridae, including Choricotyle cf. chrysophryi Van Beneden & Hesse, 1863, collected from Pagellus acarne off Algeria. No morphological character of the anterior organs suggested any special adaptation in Cy. bellones to the perforation of the crustacean cuticle. The wall of the oesophagus and of the intestine of Cy. bellones was lined with a dark pigment similar to what is usually observed in haematophagous polyopisthocotyleans, and which is derived from ingested fish blood. We noticed that an anterior elongate stem exists only in diclidophorids dwelling on parasitic isopods and never in those attached to the gills. We hypothesize that the anterior stem of the body of Cy. bellones is an anatomical adaptation for the monogenean to feed on the fish while dwelling on the isopod. We thus consider that Cy. bellones is an epibiont of the parasitic crustacean, as it uses it merely as an attachment substrate, and is not a true hyperparasiteCyclocotyla bellones Otto, 1823 (Monogenea, Diclidophoridae) est l’une des rares espèces de monogènes signalées comme hyperparasites : les vers vivent sur des isopodes cymothoïdes, eux-mêmes parasites de la cavité buccale des poissons. Nous présentons ici des observations basées sur des spécimens de monogènes nouvellement collectés de Ceratothoa parallela (Otto, 1828), un isopode parasite de Boops boops au large de l’Algérie et avons également étudié son régime alimentaire pour déterminer si Cy. bellones est bien un hyperparasite (c’est-à-dire, se nourrit-il de l’isopode ?). Nous avons également comparé la morphologie de divers monogènes appartenant à la même famille que Cy. bellones, les Diclidophoridae, dont Choricotyle cf. chrysophryi Van Beneden & Hesse, 1863, collecté sur Pagellus acarne au large de l’Algérie. Aucun caractère morphologique des organes antérieurs ne suggérait d’adaptation particulière à la perforation de la cuticule des crustacés chez Cy. bellones. La paroi de l’œsophage et de l’intestin de Cy. bellones était tapissée d’un pigment foncé semblable à ce que l’on observe habituellement chez les Polyopisthocotylea hématophages, et qui est issu du sang de poisson ingéré. Nous avons remarqué qu’une partie allongée antérieure n’existe que chez les Diclidophoridae vivant sur des isopodes parasites et jamais chez ceux attachés aux branchies. Nous émettons l’hypothèse que la partie antérieure du corps de Cy. bellones est une adaptation anatomique permettant au monogène de se nourrir du poisson tout en vivant sur l’isopode. Nous considérons donc que Cy. bellones est un épibionte du crustacé parasite, puisqu’il ne l’utilise que comme substrat pour son attachement, et n’est pas un véritable hyperparasite
Satellite DNA evolution in Corvoidea inferred from short and long reads
No full textSatellite DNA (satDNA) is a fast-evolving portion of eukaryotic genomes. The homogeneous and repetitive nature of such satDNA causes problems during the assembly of genomes, and therefore it is still difficult to study it in detail in nonmodel organisms as well as across broad evolutionary timescales. Here, we combined the use of short- and long-read data to explore the diversity and evolution of satDNA between individuals of the same species and between genera of birds spanning ~40 millions of years of bird evolution using birds-of-paradise (Paradisaeidae) and crow (Corvus) species. These avian species highlighted the presence of a GC-rich Corvoidea satellitome composed of 61 satellite families and provided a set of candidate satDNA monomers for being centromeric on the basis of length, abundance, homogeneity and transcription. Surprisingly, we found that the satDNA of crow species rapidly diverged between closely related species while the satDNA appeared more similar between birds-of-paradise species belonging to different genera
Strontium isotope analysis reveals prehistoric mobility patterns in the southeastern Baltic area
No full textWe measured 87Sr/86Sr for all available human remains (n = 40) dating from the Mesolithic to the Bronze Age (ca. 6400–800 cal BC) in Lithuania. In addition, local baselines of archaeological fauna from the same area were constructed. We identified significant and systematic offsets between 87Sr/86Sr values of modern soils and animals and archaeological animals due to currently unknown reasons. By comparing 87Sr/86Sr human intra-tooth variation with the local baselines, we identified 13 non-local individuals, accounting for 25–50% of the analysed population. We found no differences in the frequency of local vs. nonlocals between male and female hunter-gatherers. Six Mesolithic-Subneolithic individuals with 87Sr/86Sr values > 0.7200 may have come from southern Finland and/or Karelia. Two Mesolithic-Subneolithic individuals from the Donkalnis cemetery with 87Sr/86Sr values < 0.7120 likely came from the Lithuanian Baltic coast. These data demonstrate coastal-inland mobility of up to 85 km, which is also supported by archaeological evidence. The standard deviation in the intra-tooth 87Sr/86Sr indicates that mobility did not decrease with the adoption of pottery technology at ca. 5000 cal BC but rather slowly decreased during the Neolithic and Bronze Age periods. We interpret this as a result of the introduction and subsequent intensification of farming. The least mobile way of life was practised by Subneolithic coastal communities during the 4th millennium cal BC, although 87Sr/86Sr do not exclude that they migrated along the coastline
The Early Cretaceous mesofossil flora of Catefica, Portugal: angiosperms
No full textAngiosperm mesofossils are described from the Lower Cretaceous Almargem Formation exposed near the village of Catefica, Portugal, and are thought to be of Aptian-early Albian age. The mesofossil assemblage from Catefica is diverse and, in addition to the angiosperms described here, also contains a rich assemblage of non-angiosperm fossils, including leafy axes of bryophytes and lycopsids, lycopsid and salvinialean megaspores, and sporangia, sori and leaf fragments of ferns. Thereare also twigs, cones, cone scales, seeds and sporangia of several kinds of conifers. Other seed plants include 11 species of chlamydospermous seeds and vegetative axes related to the BEG group (Bennettiales-Erdtmanithecales-Gnetales). In terms of the number of plant fragments identified, angiosperms are most abundant in the Catefica assemblage and account for morethan half of all specimens. Angiosperms also dominate in number of species, but because the non-angiosperm fossils have notbeen studied in detail the total number of species in the flora is not yet established. Sixty-seven species of angiosperms arerecognized. Angiosperm diversity is mainly at the level of non-eudicots, including ANA-grade angiosperms, Chloranthaceae and magnoliids. Remains of chloranthoid angiosperms are especially common, both in the number of specimens and in numberof species recognized. About 40 % of the specimens, and more than 25 % of the species are chloranthoids. Remains of magnoliid angiosperms (Magnoliales, Laurales, Canellales, Piperales) are also prominent among the angiosperms. Eudicots are subordinate: only 3–4 % of all angiosperm specimens can be assigned confidently to eudicot angiosperms. Five new genera and six new species of angiosperms are established (Canrightia foveolata sp. nov., Elasmostemon paisii gen. et sp. nov., Endressistemon cateficensis gen. et sp. nov., Ibericarpus cuneiformis gen. et sp. nov., Proencistemon portugallicus gen. et sp. nov., Valvidistemon globiferus gen. et sp. nov.). Several other new taxa are also described, but not formally named.We thank the Paul Scherrer Institute, Villigen,Switzerland for provision of synchrotron radiation beamtime at the TOMCAT beamline X02DA of the SwissLight Source. We are also grateful to Federica Marone forher help at the beamline (project 20070197, 20080872,20100167,20110963, 20130185, 20141047, 20160140,20171476, 20190071, 20211671 to P. C. J. Donoghue, S.Bengtson, E. M. Friis and M. Rücklin), Anna Lindström forhelp with the SRXTM analyses, and Pia Bomholt Jensenfor her help with SEM at the University of Aarhus. Wealso thank Patrick S. Herendeen and Steven R. Manchesterfor valuable comments to the manuscript. Support for thisresearch was also obtained from the Swedish ResearchCouncil (2014-5228 to E. M. Friis), United States NationalScience Foundation (BSR-8708460, DEB-9616443, DEB-1348456, DEB-1748286, to PRC and colleagues) the OakSpring Garden Foundation, the Czech Grant Agency (project20-06134S) and the Portuguese Science Foundation (FCT),under the projects UIDB/04292/2020 and UIDP/04292/2020,granted to MARE, and LA/P/0069/2020, granted to theAssociate Laboratory ARNET.</p
Mummified Dicroidium (Umkomasiales) leaves and reproductive organs from the Upper Triassic of South Australia
No full textThe Leigh Creek Coal Measures incorporate unusually low-rank coals from the Upper Triassic of South Australia. Associated fluviolacustrine deposits contain well-preserved, partly mummified plant remains dominated by corystosperm seed ferns. The assemblage comprises seven species of Dicroidium, including D. odontopteroides, D. lineatum, D. dubium, D. zuberi, and Dicroidium spp. A, Band C, and associated reproductive organs, including various fragments of cupulate structures (Umkomasia sp. cf. U. quadripartita and Fanerotheca sp. cf. F. waldeckiformis) and pollen organs (Pteruchus africanus), all having excellent cuticle preservation. Based on a comprehensive analysis of more than 550 individual specimens, we (1) document diagnostic epidermal and cuticular features forfoliage and reproductive organs, (2) provide an identification key for the Dicroidium species present, and (3) infer affiliations between reproductive organs and particular leaf species based on correspondence in epidermal anatomy and cuticle micromorphology and on mutual-occurrence data. Collectively, the Leigh Creek material contributes towards a more robust and realistic systematic classification of Umkomasiaceae, offers a rare chance for whole-plant reassembly of individual species, and refines reconstruction of the Dicroidium dominated forest ecosystems in the middle to high latitudes of the Late Triassic greenhouse world.This work was supported by the German Science Foundation (DFG Emmy Noether grant BO3131/1–1 ‘Latitudinal Patterns in Plant Evolution’ to B.B.) and a grant from the Swedish Research Council (VR grant number 2018-04527) to S.M. </p
