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1.
The first data on the distribution of planktonic foraminifers and radiolarians in the Mt. Ak-Kaya section, the central Crimean Mountains, are considered. According to the analyzed distribution of foraminifers, the Upper Cretaceous deposits of the section are subdivided into three biostratigraphic units: the Marginotruncana austinensis-Globotruncana desioi (presumably upper Coniacian), Sigalia carpatica (uppermost Coniacian-lower Santonian), and Contusotruncana fornicata-Marginotruncana marginata (upper Santonian) beds. Subdivisions substantiated by distribution of radiolarians are the Alievium praegallowayi-Crucella plana (upper Coniacian-lower Santonian), Alievium gallowayi-Crucella espartoensis (the upper Santonian excluding its uppermost part), and Dictyocephalus (Dictyocryphalus) (?) legumen-Spongosaturninus parvulus (the uppermost Santonian) beds. The Contusotruncana fornicata-Marginotruncana marginata Beds are concurrent to the middle part of the Marsupites laevigatus Zone coupled with the Marsupites testudinarius Zone (the uppermost Santonian). The Alievium gallowayi-Crucella espartoensis Beds are correlative with the upper part of the Alievium gallowayi Zone in the Californian radiolarian zonation. The cooccurring assemblages of planktonic foraminifers and radiolarians provide a possibility to correlate the Coniacian-Santonian deposits within the Crimea-Caucasus region.  相似文献   

2.
A scheme of radiolarian zonal subdivision is proposed for the upper Albian–Santonian of the Tethyan regions of Eurasia. The upper Albian contains one zone: Crolanium triangulare; the Cenomanian contains three zones: Patellula spica (lower Cenomanian), Pseudoaulophacus lenticulatus (middle Cenomanian), and Triactoma parva (upper Cenomanian); the Turonian contains four zones: Acanthocircus tympanum (lower Turonian (with no upper part)), Patellula selbukhraensis (upper part of the lower Turonian), Phaseliforma turovi (middle Turonian (with no upper part)), and Actinomma (?) belbekense (upper part of the middle Turonian–upper Turonian); the Coniacian contains two zones: Alievium praegallowayi (lower part of the Coniacian) and Cyprodictyomitra longa (upper part of the Coniacian); the Santonian contains three zones: Theocampe urna (lower Santonian), Crucella robusta (middle Santonian–lower part of the upper(?) Santonian), and Afens perapediensis (upper part of the upper Santonian). The biostratigraphic subdivisions are correlated with biostrata in the schemes proposed previously for the Tethys and Pacific. A new species Patellula selbukhraensis Bragina sp. nov. is described.  相似文献   

3.
Data on the distribution of radiolarians and planktonic and benthic foraminifers are obtained for the first time from the Alan-Kyr Section (Coniacian–Campanian), in the central regions of the Crimean Mountains. Radiolarian biostrata, previously established from Ak-Kaya Mountain (central regions of the Crimean Mountains) were traced: Alievium praegallowayi–Crucella plana (upper Coniacian–lower Santonian), Alievium gallowayi–Crucella espartoensis (upper Santonian without the topmost part), and Dictyocephalus (Dictyocryphalus) (?) legumen–Spongosaturninus parvulus (upper part of the upper Santonian). Radiolarians from the Santonian–Campanian boundary beds of the Crimean Mountains are studied for the first time, and Prunobrachium sp. ex gr. crassum–Diacanthocapsa acanthica Beds (uppermost Santonian–lower Campanian) are recognized. Bolivinoides strigillatus Beds (upper Santonian) and Stensioeina pommerana–Anomalinoides (?) insignis Beds (upper part of the upper Santonian–lower part of the lower Campanian) are recognized. Eouvigerina aspera denticulocarinata Beds (middle and upper parts of the lower Campanian) and Angulogavelinella gracilis Beds (upper part of the upper Campanian are recognized on the basis of benthic foraminifers. These beds correspond to the synchronous biostrata of the East European Platform and Mangyshlak. Marginotruncana coronata-Concavatotruncana concavata Beds (Coniacian–upper Santonian), Globotruncanita elevata Beds (terminal Santonian), and Globotruncana arca Beds (lower Campanian) are recognized on the basis of planktonic foraminifers. Radiolarian and planktonic and benthic foraminiferal data agree with one another. The position of the Santonian–Campanian boundary in the Alan-Kyr Section, which is located stratigraphically above the levels of the latest occurrence of Concavatotruncana concavata and representatives of the genus Marginotruncana, is refined, i.e., at the level of the first appearance of Globotruncana arca. A gap in the Middle Campanian–lower part of the upper Campanian is established on the basis of planktonic and benthic foraminifers. The Santonian–Campanian beds of the Alan-Kyr Section, on the basis of planktonic foraminifers and radiolarians, positively correlate with synchronous beds of the Crimean-Caucasian region, and beyond. Benthic foraminifers suggest a connection with the basins of the East European Platform.  相似文献   

4.
Diverse radiolarians (over 70 species) are detected in cherty rocks above the bituminous shale horizon, the marker of anoxic event OAE-2 recorded across the Cenomanian-Turonian boundary in the upper part of the Ananuri Formation of flyschoid deposits, the Lazarevskoe area of the western Caucasus. The radiolarian assemblages studied are comparable in composition with radiolarians from concurrent Cenomanian-Turonian boundary strata in other Mediterranean regions (e.g., in the Crimea and Turkey). The lower radiolarian assemblage includes index species Dactyliosphaera silviae of synonymous Cenomanian zone. Alievium superbum present in the upper assemblage is index species of the relevant Turonian zone. Within the studied flyschoid sequence, sediments indicative of the above event (bituminous shales and cherts) are confined to upper elements of flysch rhythms.  相似文献   

5.
The first data on the distribution of Radiolaria and planktonic Foraminifera in the section at Biyuk-Karasu River in central part of the Crimean Mountains, are presented. Based on the study of radiolarian findings, the upper Cretaceous deposits of Biyuk-Karasu section are subdivided into the following biostratigraphic units: Alievium superbum-Phaseliforma turovi (middle Turonian), Dactylodiscus longispinus-Patulibracchium (?) quadroastrum (upper Turonian), and Orbiculiforma quadrata-Patellula sp. B (Turonian-Coniacian boundary deposits). The stratigraphic interval of Alievium superbum-Phaseliforma turovi has been previously characterized by the complex of Alievium superbum-Phaseliforma sp. A (middle Turonian, Mt. Chuku section, SW of the Crimean Mountains, and middle Turonian, Mt. Ak, central part of the Crimean Mountains). Based on the study of Foraminifera findings, the following biostratigraphic subdivisions were identified: Whiteinella paradubia (lower-lower part of the middle Turonian), Marginotruncana pseudolinneiana (uppermost middle Turonian), and Marginotruncana coronata (upper Turonian). The complex of beds with Marginotruncana pseudolinneiana and Marginotruncana coronata are comparable to the deposits of zones of same name in the Crimean-Caucasian region.  相似文献   

6.
New data on the radiolarians and foraminifers (planktonic and benthic) from the lower part of Struganik limestones (Bre??e Section, Western Serbia) are presented. The Afens perapediensis Zone of a new detailed scale based on radiolarians for the Tethyan supra-region was traced for the first time. This allowed classification of the studied deposits to a narrow stratigraphic interval, that is, the upper Santonian. The age of the studied sediments is determined in the Santonian for planktonic foraminifera because of the joint presence of abundant Marginotruncana (extinct in the latest Santonian) and Globotruncana linneiana (d’Orbigny) (which appeared in the early Santonian). The radiolarian and planktonic and benthic foraminifera data agree with one another.  相似文献   

7.
Lithological evidence, benthic foraminiferal census counts, and X-ray fluorescence (XRF) scanner-derived elemental data were integrated with planktonic foraminiferal biostratigraphy and bulk carbonate stable isotopes to retrace the Turonian to early Campanian paleoenvironmental evolution and sea-level history of the Tarfaya Atlantic coastal basin (SW Morocco). The lower Turonian is characterized by laminated organic-rich deposits, which contain impoverished benthic foraminiferal assemblages, reflecting impingement of the oxygen minimum zone on the shelf during a sea-level highstand. This highstand level is correlated to the global transgressive pulse above the sequence boundary Tu1. The appearance of low-oxygen tolerant benthic foraminiferal assemblages dominated by Gavelinella sp. in the middle to upper Turonian indicates an improvement in bottom water oxygenation, probably linked to offshore retraction of the oxygen minimum zone during a regressive phase. This interval is marked by major regressive events expressed by a series of erosional truncations associated with the prominent sequence boundaries Tu3 and/or Tu4. Dysoxic–anoxic conditions recorded in the upper Santonian of the Tarfaya Basin coincide with the eustatic sea-level rise prior to Sa3 sequence boundary. The lower Campanian transgression, only recorded in the southern part of the Tarfaya Basin, coincided with substantial deepening, enhanced accumulation of fine-grained clay-rich hemipelagic sediments and improved oxygenation at the seafloor (highest diversity and abundance of benthic foraminiferal assemblages). Stable isotope data from bulk carbonates are tentatively correlated to the English Chalk carbon isotope reference curve, in particular the Hitch Wood Event in the upper Turonian, the Navigation Event in the lower Coniacian, the Horseshoe Bay Event in the Santonian and the Santonian/Campanian Boundary Event.  相似文献   

8.
New data on Middle Triassic radiolarians from the central part of Kotel’nyi Island are discussed. The Triassic section is represented by clays and mudstones with diverse macro- and microfossils, which confirm the presence of lower Anisian, upper Anisian, and upper Ladinian sediments on the island. The lower Anisian Substage 10–15 m thick is composed of clays with ammonoid species Karangatites evolutus. The upper Anisian Substage 20 m thick consists of clays with phosphate concretions and bivalves Daonella sp. cf. D. moussoni Merian, D. americana Smith, ammonoid form Indigirophyllites sp. ex gr. I. spetsbergensis (Oeberg), and radiolarian assemblage with Glomeropyle boreale Bragin. The upper Ladinian Substage 25–30 m thick is composed of clays with phosphate concretions and bivalves including Daonella frami Kittl., ammonoid species Indigirophyllites sp. ex gr. I. oimekonensis Popow, and radiolarian assemblage with Muelleritortis firma (Gorican). The middle Anisian and lower Ladinian substages are missing, which may be explained by the incompleteness of the section. The Middle Triassic section of Kotel’nyi Island is first stratified on the basis of radiolarians, which are supplemented by the data on cephalopods and bivalves. Glomeropyle saccum Bragin, sp. nov. is described.  相似文献   

9.
The litho- and biostratigraphy of the Craie de Villedieu Formation (Coniacian-Santonian)of western France are described in detail. The formation is subdivided into three members each containing a number of lithologically distinct named hardgrounds and marker beds. These constitute an onlapping sequence that thins from > 15 m in the NE around Cangey and Villedieu-le-Château, to < 2 m in the SW around St Michel-sur-Loire, a distance of 70 km. Thickness variation is related to the interaction of differential subsidence with eustatic transgression. Comparison with the Chalk Rock Formation of southern England indicates that transgressive and regressive hardground suites may be differentiated on bed geometry and hardground surface characteristics. The Craie de Villedieu rests everywhere on a regional hardground that coincides with the Turonian/Coniacian boundary in expanded successions, but probably marks a significant hiatus. South-west of Tours, onlap results in Santonian strata resting disconformably on strata of Turonian age. The basal Craie de Villedieu contains a succession of three Coniacian ammonite faunas characterized by Peroniceras and Forresteria (Harleites) (oldest), Gauthiericeras margae (Schlüter), and Protexanites (youngest). Volviceramus ex gr. involutus (J. de C. Sowerby) occurs with the two uppermost ammonite assemblages. A Santonian ammonite fauna dominated by Placenticeras polyopsis (Dujardin) occurs with Texanites gallicus Collignon and common Cladoceramus in the middle of the formation. Cordiceramus ex gr. cordiformis (J. de C. Sowerby) is recorded with Santonian ammonites in the upper part of the formation. A correlation with the Micraster zones of chalk facies is suggested, based on the inoceramid stratigraphy. The record of T. gallicus in association with Cladoceramus affords the first direct evidence for the position of the base of the Santonian in the Anglo-Paris Basin.  相似文献   

10.
In distribution areas of the Pekul’neiveem and Chirynai formations customary distinguishable in the Koryak Upland, complicated tectonostratigraphic units are composed of alternating thrust sheets of different lithologic composition and age, which are juxtaposed because of widespread thrust faulting, as is proved by the radiolarian analysis. Nineteen radiolarian assemblages of different age are first established here in the Lower Jurassic-Hauterivian succession of siliceous-volcanogenic sediments. In the Lower Jurassic interval, the lower and upper Hettangian, lower and upper Sinemurian, and Pliensbachian beds are recognized. Paleontological characterization is also presented for the Aalenian (or Toarcian?-Aalenian), upper Bajocian, lower and upper Bathonian, and Callovian beds of the Middle Jurassic. Within the Upper Jurassic, the Oxfordian-early Kimmeridgian, late Kimmeridgian-early Tithonian, Tithonian, and late Tithonian-early Berriasian radiolarian assemblages are distinguished. The late Berriasian-early Valanginian, middle-late Valanginian, and Hauterivian radiolarian assemblages are first recognized or compositionally revised. Radiolarians and lithofacies data are used to correlate the tectonostratigraphic units and individualize the jasper-alkali basaltic (lower Hettangian), chert-terrigenous (Hettangian-Sinemurian), jasper-cherty (Pliensbachian-Aalenian), jasper (Bajocian-Hauterivian), jasper-basaltic (upper Bajocian-Valanginian), Fe-Ti basaltic (upper Bajocian-Bathonian), tuffitejasper-basaltic (Bathonian-Hauterivian), and terrigenous-volcanogenic (Bajocian-Valanginian) sequences. The correlation results are extrapolated into other continental areas flanking the Pacific, i.e., to the western Kamchatka, northern and northwestern coastal areas of the Sea of Okhotsk, where the analogous radiolarian assemblages are characteristic of comparable allochthonous units of terrigenous-siliceous-volcanogenic sediments.  相似文献   

11.
Sections and fusulinids of the Bolorian (presumably) and Kubergandian (lower part) stages in the Sanandaj-Sirjan tectonic zone are described. Two fusulinid assemblages are distinguished in a most complete section near Sirjan. The lower one is represented by Skinnerella, Paraleeina, and relatively primitive Misellina forms, whereas Armenina, Kubergandella, and Yangchienia species appear in the upper assemblage and suggest its early Kubergandian age. Accordingly, the lower assemblage is attributed to the Bolorian Stage, although it is lacking fusulinids typical of this stage except for the primitive Misellina morphotypes. Fusulinids from the Tange-Darchaleh section near Qomsheh (Shahreza) are typical of the Kubergandian Stage. The described three new species of the genus Skinnerella are close to morphotypes known from younger (Murgabian) deposits and represent their ancestral forms most likely.  相似文献   

12.
The paper presented is the first comprehensive, fully quantitative, high resolution study of marine palynology from an OAE3 black-shale environment. It is based on 175 m core spanning the upper Turonian to lower Santonian at Tarfaya, Morocco, NW Africa, which has been sampled from centimetre to 3 m intervals. The results are integrated and discussed with lithology and geochemistry data to (1) distinguish between potential changes in production and preservation of total organic carbon (TOC) accumulation and (2) constrain the stratigraphic position of the Oceanic Anoxic Event 3 (OAE3).The succession is characterized by increased total organic carbon (TOC), varying between 1% and 19% (average about 6%). Distinct black-shale horizons of variable thickness appear episodically throughout the succession, with higher frequency in the late Turonian. Higher TOC contents do not strictly correlate to lithologic black-shales or peaks of a specific taxon of organic-walled algae. The palynomorph spectrum is strongly dominated by organic-walled algae, with the ratio of terrigenous sporomorphs to organic-walled algae (t/m index) varying between zero and 0.05 (average 0.01). The dominance of algal organic matter is corroborated by the prevalence of Type I kerogen identified using Rock-Eval pyrolysis. Dinocyst diversity is low, with the absolute taxa number varying from 7 to 27 between single samples. The peridinioid/gonyaulacoid ratio of dinocysts (p/g ratio) shows strong fluctuations, varying between 1 and 283 (average of about 100).The upper Turonian interval is dominated by Bosedinia spp., a dinocyst taxon formerly described as abundant only in lacustrine sediments from the Oligocene and Miocene of SE Asia. This dominance is episodically modified by the increase of the warm-temperate waters dinocysts fraction, here mainly represented by the genera Alterbidinium, Isabelidinium and Spinidinium. Within the Coniacian-Santonian, black-shale horizons are limited in number and are concentrated within the upper Coniacian to lower Santonian interval. The dinocysts show alternating, prominent peak abundances of Palaeohystrichophora spp. and the warm-temperate water dinocysts fraction, here mainly represented by the genera Trithyrodinium and Chatangiella. However, a final episode of increased proportions of Bosedinia spp. is confined to a 5 m thick black-shale horizon closely spanning the Coniacian-Santonian boundary.Changes in the ratio of total sulphur to total organic carbon (TS/TOC) reflect fluctuating oxygen contents of bottom waters throughout the late Turonian to Santonian. These are significantly parallelled by the alternation of dinocysts assemblages suggestive of enhanced upwelling and water column stratification respectively, probably reflecting changes in the mode of TOC accumulation. Accordingly, preservation largely prevails during the late Turonian interval and changes towards increased production within the Coniacian-Santonian. However, a final preservation-event is probably represented by the black-shale horizon closely spanning the Coniacian-Santonian boundary (top Dicarinella concavata foraminifera zone), which may reflect an episodic shutdown of a major upwelling cell. It is thus proposed, that the “culmination” of the OAE3 at Tarfaya may represent intermittent preservation of TOC within an otherwise high productivity environment related to a global cooling trend.  相似文献   

13.
《Cretaceous Research》2012,33(6):685-699
Albian pelagic successions of the Nebeur area in northwestern Tunisia consist of radiolarian-bearing and organic-rich black shale beds, which represent the lower part of the Fahdene Formation. The carbonate content of the organic-rich beds ranges between 40 and 48%. Total organic carbon (TOC) analyses via Rock Eval pyrolysis yielded values ranging between 0.7 and 2.8% and a mixed marine/terrestrial origin. Tmax values vary between 424 and 450 °C, indicative of submature to mature organic matter. High resolution planktic foraminiferal and radiolarian biostratigraphy suggest that the black shales beds span the mid- to late Albian, confined to the middle part of the Ticinella primula zone, upper Biticinella breggiensis zone and lower appeninica + buxtorfi zone. Episodes of organic-rich deposition in the “Tunisian Trough” are interpreted as being the sedimentary record of the global oceanic anoxic events OAE1b, c, and d respectively. Age-diagnostic radiolarian assemblages recovered from late Albian organic-rich black shales lie within the UA13–UA14 boundary biochronozones. The abundance of radiolarian and calcispheres (i.e. pithonella) within the black shales suggests high productivity periods and eutrophic conditions probably triggered by upwelling currents.  相似文献   

14.
The marine Pliocene-Pleistocene sequence of Iceland contains four main assemblages of mollusks: (1) Venerupis rhomboides et al., (2) Serripes groenlandicus et al., (3) Portlandia arctica et al., and (4) recent species. Analysis of the stratigraphic distribution of 100 species shows that the percentage of extinct species in the assemblages decreases from 40% in the oldest to 4–8% in the youngest. There is also a change from south boreal affinities in the oldest assemblage to north boreal in the youngest. The molluskan assemblages of Iceland can be correlated with Pliocene-Pleistocene assemblages of England and North Europe: (1) Coralline Crag, (2) Red Crag—lower part of the Icenian strata, (3) upper part of the Icenian-Cromerian strata. The upper boundaries of the Pliocene and Eopleistocene are defined by paleomagnetic data and radiological dating. The upper boundary of the Pliocene presumably should be established in the basalts lying between the Tjörnes and the Breidavik deposits by changes between the second and third mollusk assemblages and by the Gilsa paleomagnetic event.  相似文献   

15.
Changes in morphological diversity and taxonomic composition of late Albian-early Turonian foraminiferal and radiolarian assemblages from the northern Peri-Tethys are considered. Several stages are defined in evolution of planktonic foraminifers: polytaxic (Albian-Cenomanian), oligotaxic (Cenomanian-Turonian boundary period), and polytaxic (Turonian). The Albian-Cenomanian stage was characterized by intense development of rotaliporids representing an intricate group of planktonic foraminifers, which became extinct in the terminal Cenomanian. An intense speciation of the radiolarian genus Crolanium and last occurrences of its most species, the index species C. cuneatum included, was characteristic of the terminal Albian. Spheroid and discoid radiolarians were dominant in the Cenomanian, while the Turonian was marked by intense development of all the radiolarian morphotypes.  相似文献   

16.
Radiolarians from the lower part of the Karai Formation (upper Albian-middle Cenomanian) are studied in detail for the first time. Among over 50 radiolarian species identified in the formation, there are Acaeniotyle amplissima (Foreman), Savaryella novalensis (Squinabol), S. quadra (Foreman), Vitorfus campbelli Pessagno, Archaeodictyomitra montisserei (Squinabol), Holocryptocanium barbui Dumitrica, Pseudoeucyrtis sp. cf. Ps. spinosa (Squinabol), Stichomitra communis Squinabol, Tubilustrionella transmontanum (O’Dogherty), and others. The discovered radiolarians are divided into the Halesium triacanthum-Orbiculiforma nevadaenis (late Albian-early Cenomanian), Crucella latum-Cryptamphorella micropora (late Albian?-early Cenomanian), and Becus sp. B-Godia concava (terminal Albian-middle Cenomanian) assemblages. In general, the Albian-Cenomanian radiolarians of South India are comparatively less diverse than the concurrent assemblages of the Mediterranean region and California. In taxonomic composition and morphological peculiarities, they are comparable with the Aptian-Albian radiolarians of Western Australia (Ellis, 1993). Consequently it can be postulated that sea basins of South India were situated during the Albian-Cenomanian in the temperate latitudes of the Southern Hemisphere.  相似文献   

17.
The Mid-Cretaceous ‘upper siliceous zone’ of the Vigla Limestone is studied in detail along the Paliambela section of northwestern Greece. Within it two radiolarite horizons can be identified, the lower being rich in organic matter and named herein as the ‘Fourcade level’. The preserved organic matter is of planktic/bacterial origin and of low thermal maturity. The nannoflora contained within the lower marly argillites consists of a poorly preserved and oligospecific assemblage characterised by the total absence of Nannoconids. Radiolarian assemblages yielded from the Fourcade level are dominated by the family Archaeodictyomitridae. Integrated calcareous nannofossil and radiolarian biostratigraphic results suggest an Early Aptian age for the Fourcade level, which can be thus considered as the local expression of the globally recognised Early Aptian Oceanic Anoxic Event (OAE 1a). To cite this article: T. Danelian et al., C. R. Geoscience 334 (2002) 1087–1093.  相似文献   

18.
The deglacial transition between oxygen-isotope Stages 6 and 5e (about 127,000 yr B.P.) is marked by both oxygen isotopic depletion and estimated sea-surface temperature (SST) increase in two subantarctic Indian Ocean cores. The data show synchroneity between warming of foraminifera-based SST estimates and depletion of δ18O, but an earlier warming trend on the basis of radiolarian SST estimates. These data have been previously interpreted to indicate that the high-latitude Southern Ocean warms prior to significant melting of glacial-age ice sheets. Comparison of core-top assemblages with surface and subsurface conditions in the Southern Indian Ocean reveals that (1) a three-part foraminiferal zonation reflects the surface hydrographic regime, with abrupt faunal transitions at two major fronts: the Subtropical Convergence (STC) and the Antarctic Polar Front (APF); and (2) a two-part radiolarian zonation coincides with a two-part subsurface hydrographic regime, with an abrupt faunal transition corresponding to the southern terminus of subtropical lower water (STLW) between the STC and the APF. It is suggested that shifts of these surface and subsurface regimes are recorded by these foraminiferal and radiolarian assemblages. In this interpretation, the observed lead of radiolarian SST with respect to δ18O indicates an early response to a southward shift of STLW, while the later foraminiferal SST warming indicates a southward shift of the STC. Thus, the origin of the Southern Hemisphere SST lead may be related to STLW, which emanates from the subtropical gyres, rather than the polar regions.  相似文献   

19.
The new tribe Taimyralticini trib. nov., new genus Taimyraltica gen. nov. and new species Taimyraltica calcarata sp. nov. (Coleoptera: Chrysomelidae: Galerucinae) are described from Upper Cretaceous (Santonian) Taimyr amber of northern Siberia (Yantardakh locality). The new genus shares characters with genera of the tribe Alticini (small size, transverse antebasal groove on pronotum, regular punctate-striate elytra) and the Galerucini (narrow, non-swollen metafemora). A possible apomorphy of the new genus and tribe is a large and acute metatibial spur, erect and oriented transversely to the longitudinal axis of tibia. This character state is unknown in recent and fossil genera of Galerucinae. Early evolution and divergence of leaf beetles are discussed, and a Jurassic and Early Cretaceous subfamily radiation is proposed. Fossil galerucines are reviewed. The oldest Phyllotreta is recorded from the lower Miocene of Izarra (Spain). Our findings show an extreme rarity of Phytophaga in Taimyr amber from Yantardakh. Absence of Phytophaga was recorded earlier at Obeschayuschiy (Santonian-Campanian of the Magadan Region) and compared with their much larger share in Khetana (north of Khabarovsk Krai); we find nearly the same differences between Taimyr amber from Yantardakh and Canadian amber. In Obeschayuschiy this appears due to the Mesophytic character of the flora. It is assumed that the Santonian amber gymnosperm forest of the Khatanga Basin had the same character.  相似文献   

20.
The thorough study of the Upper Triassic reference section located at the Tikhaya River in the central part of Kotel??nyi Island and characterized by uniform clayey lithology and containing diverse cephalopod, molluscan, and radiolarian assemblages made it possible to specify its structure and paleontological characteristic and establish for the first time the upper Anisian Sirenites yakutensis Zone. It is shown that different Late Triassic faunal groups are represented by mixed dominant Boreal and subordinate Tethyan elements. Such proportions are observable through the entire section beginning from the lower Carnian to upper Norian layers. The peculiar taxonomic composition of Late Triassic radiolarian and cephalopod assemblages provides grounds for attributing the region to an autonomous paleobiochore (New Siberian subprovince). The occurrence of both Siberian and Canadian elements in the Late Triassic faunas emphasizes the specific position of this paleobiochore determined by wide connections between basins at that time.  相似文献   

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