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Wyszukujesz frazę "ammonoidea" wg kryterium: Temat


Tytuł:
Early Cretaceous ammonites and dinoflagellates from the Western Tatra Mountains, Poland
Autorzy:
Vasicek, Z.
Błażejowski, B.
Gaździcki, A.
Król, M.
Lefeld, J.
Skupień, P.
Wierzbowski, A.
Tematy:
Ammonoidea
Anomiidae
Dinoflagellata
Valanginian
Hauterivian
Western Carpathians
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/2082277.pdf  Link otwiera się w nowym oknie
Opis:
The first Early Cretaceous (Valanginian–Hauterivian) ammonite fauna from the lower part of the Kościeliska Marl Formation (Wściekły Żleb Member) of the Lower Sub-Tatric (Krížna) Nappe, in the Lejowa Valley of the Tatra Mountains are described. The fauna is precisely placed in the succession and consists of five species: Olcostephanus densicostatus, Spitidiscus cf. cankovi, Criosarasinella cf. subheterocostata, Crioceratites primitivus, and Crioceratites coniferus and additionally an aptychus Didayilamellaptychus seranonis. Remarkable are the valves of anomiid bivalves attached to body chamber of large size heteromorph ammonite C. primitivus. Moreover, a variety of stratigraphically important organic-walled dinoflagellate cysts are recovered from this locality. Dinoflagellates: Cymososphaeridium validum, Circulodinium vermiculatum, and representatives of Bourkidinium define the Upper Valanginian–Lower Hauterivian Sentusidinium sp. A Dinocyst Subzone of the Cymososphaeridium validum Zone. The character of deposits, the palynofacies, and associations of dinoflagellate cysts indicate a calm marine outer neritic environment.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sexual dimorphism in the Bathonian morphoceratid ammonite Polysphinctites tenuiplicatus
Autorzy:
PARENT, HORACIO
ZATOŃ, MICHAŁ
Tematy:
ammonoidea
morphoceratidae
dimorphism
macroconch
microconch
jurassic
poland
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/945448.pdf  Link otwiera się w nowym oknie
Opis:
Asphinctites tenuiplicatus [M] and Polysphinctites secundus [m] from the Asphinctites tenuiplicatus Zone (Early Bathonian), are usually considered as a sexual dimorphic pair, although authors describe them as separate species. We used statistical methods to test the sexual dimorphic correspondence between those morphospecies, based on a rather large sample of well-preserved macro- and microconchs derived from a single horizon of calcareous concretions in the Polish Jura. Our results indicate that both dimorphs or sexes have identical ontogeny up to a critical diameter, from which they diverge towards the characteristic morphology and sculpture of each dimorph. Thus, both dimorphs are described as a single species: Polysphinctites tenuiplicatus [M and m]. After review of the several nominal species usually assigned to the genera Asphinctites and Polysphinctites throughout their stratigraphic and biogeographic range in the Early Bathonian of the Tethys, it is concluded that they actually correspond to only two species of a single lineage. The corresponding name for the lineage should be Polysphinctites (= Asphinctites as a junior synonym).
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new type of shell malformation caused by epizoans in Late Jurassic ammonites from Central Russia
Autorzy:
MIRONENKO, ALEKSANDR A.
Tematy:
ammonoidea
craspeditidae
kachpurites
parasites
epifauna
jurassic
russia
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/945743.pdf  Link otwiera się w nowym oknie
Opis:
A new type of shell damage on Late Jurassic ammonite Kachpurites fulgens is described. The new type of shell malformation consists of small elongated pits, arranged in groups on the surface of ammonite shell and concentrated near the terminal aperture. The examination of the pits demonstrated no signs of drilling, biting, or healing of punctures. The shell layers in the pits are bent downward without changing in thickness. At the same time the pits, in some cases, significantly distort the shape of the shell walls. Deformed growth lines are associated with some of the pits. All of this supports the hypothesis that the pits had been formed by epifauna located at a flexible uncalcified part of the periostracum in the apertural region of the growing ammonite shell. It is likely that epizoan attachment led to the deformation of the thin periostracum film and to the distortion of the growing shell wall. The nature of epizoans is discussed, but remains unclear due to their rather poor preservation. The relationship between epizoans and ammonites is also an open question: they could have been parasites, but other types of biotic relationships cannot be entirely ruled out.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The mid-Famennian ammonoid succession in the Rhenish Mountains: the "annulata Event" reconsidered
Autorzy:
Korn, D.
Tematy:
Late Devonian
Famennian
Rhenish Mountains
Ammonoidea
black shales
diversity
Pokaż więcej
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Powiązania:
https://bibliotekanauki.pl/articles/2058845.pdf  Link otwiera się w nowym oknie
Opis:
The mid-Late Devonian pelagic sedimentary successions of the Rhenish Mountains and other regions show a double black shale horizon called the annulata Black Shale. It marks, at the species level, a prominent faunal turnover of ammonoids from the Prolobites delphinus Zone into the Platyclymenia annulata Zone. An analysis of ammonoid genera distribution, phylogenetic relationships, andmorphospace occupation demonstrates that the "annulata Event" does not correspond to a crisis of the group and does not fulfill the criteria of a major biotic event.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exploring the limits of morphospace: ontogeny and ecology of Late Visean ammonoids from the Tafilalt, Morocco
Autorzy:
Klug, C.
De Baets, K.
Korn, D.
Tematy:
paleoecology
morphospace
ontogenesis
ecology
Late Visean
ammonoid
Ammonoidea
Morocco
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/22457.pdf  Link otwiera się w nowym oknie
Opis:
Early late Viséan ammonoid assemblages in Morocco are composed of diverse and well-preserved specimens. The material was found in a plain in the Tafilalt (eastern Anti-Atlas). Here, we describe mass-occurrences of juvenile specimens, in which subadult and adult specimens occur in low numbers. The juveniles of some species display a conch morphology that differs fundamentally from the adult stages. Accordingly, we emend the species diagnoses of Goniatites lazarus as well as Calygirtyoceras darkaouaense, introduce the species Entogonites bucheri sp. nov., and discuss possible ecological implications of the morphologic changes throughout ontogeny. In particular, we compare the changes in conch morphology through ontogeny in the light of Pareto Optimiality according to which the morphology of organisms would fill a polygon or polyhedron in morphospace. Data points in one of the vorteces of the polyhedron indicate optimisation for the corresponding task. Although shape is not a proof of function, it appears plausible that juvenile conchs were selected rather for compactness while adult conchs were positively selected for conchs with improved hydrodynamic properties. This appears plausible because at small conch diameters, swimming movements will not suffice for effective translocation and a planktonic mode of life is likely.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Form and formation of flares and parabolae based on new observations of the internal shell structure in lytoceratid and perisphinctid ammonoids
Autorzy:
RADTKE, GREGOR
HOFFMANN, RENÉ
KEUP, HELMUT
Tematy:
ammonoidea
ultrastructure
megastriae
temporary aperture
episodic growth
jurassic
cretaceous
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/945749.pdf  Link otwiera się w nowym oknie
Opis:
The ultrastructure of pristine shells of Jurassic and Cretaceous lytoceratid and perisphinctid ammonoids indicates that flares and parabolae represent homologous structures. Both mark an interruption of shell growth. We dismiss earlier interpretations of parabolae as actual aperture, relics of resorbed apophyses or superstructure of the musculature associated to a semi-internal shell. Instead we propose an episodic growth model including several growth stops at the aperture during the formation of a frill-like aperture for parabolae and flares. Such an aperture is composed of the outer prismatic layer, the nacreous layer and an apertural prismatic coating. Here, we observed the apertural prismatic coating for the first time as an integral part of flares and parabolae. The apertural prismatic coating covers only the inner surface of the frill and was secreted by a permanent mantle cover indicating a prolonged period without the production of new shell material. Parabolae differ from flares by their general shape and the presence of ventro-lateral parabolic notches and nodes. The notches were formed by folding of the frill and had the potential to form semi-open spines. The corresponding parabolic nodes are caused by an outward swelling of the shell-secreting mantle tissue producing new shell material at the position of the folding. New shell material that belongs to the conch tube is attached to the base of flares and parabolae after withdrawal of the mantle edge representing the continuation of shell growth. Usually, the frilled aperture associated with flares and parabolae were removed during lifetime. This study reports on flares in Argonauticeras for the first time. In this genus they are typically associated with varices.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The origin of ammonoid locomotion
Autorzy:
Klug, C
Korn, D.
Tematy:
phylogenesis
Bactritida
ontogenesis
Ammonoidea
conch
coiling
Devonian
paleontology
locomotion
ammonoid
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/21156.pdf  Link otwiera się w nowym oknie
Opis:
Evolution of the coiled ammonoid conch from the uncoiled bactritid conch was probably coupled with changes in manoeuvrability and swimming velocity. The gradual transformation of uncoiled to coiled ammonoid conchs has essential functional consequences. The radical change in conch geometry during phylogeny but also in ontogeny of early ammonoids implies a shift of the aperture from an original roughly downward, via a downward oblique and an upward oblique to an upward orientation, presuming a neutrally buoyant condition of the ammonoid animal. Similar trends were reconstructed for the three main ammonoid lineages in the Middle Devonian, the agoniatitid, the anarcestid, and the tornoceratid lineages. This allowed an increase in manoeuvrability and in the maximum horizontal swimming speed.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Terminal Maastrichtian ammonites from Turkmenistan, Central Asia
Autorzy:
Machalski, M.
Jagt, J.W.M.
Alekseev, A.S.
Jagt-Yazykova, E.A.
Tematy:
paleontology
Maastrichtian
ammonite
Turkmenistan
Central Asia
Ammonoidea
extinction
paleobiogeography
Cretaceous
Paleogene
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/20971.pdf  Link otwiera się w nowym oknie
Opis:
A complete uppermost Maastrichtian–Danian succession in the Sumbar River section, western Kopet Dagh (southwest Turkmenistan, Central Asia), constitutes one of the few instances in the world where the fossil record of the last ammonites can be directly positioned with respect to the iridium−rich, impact−related clay layer, which defines the Cretaceous–Paleogene (K–Pg) boundary. Two ammonite taxa, Baculites cf. vertebralis and Hoploscaphites constrictus johnjagti, range up to a level directly beneath the K–Pg boundary clay in the Sumbar River section. Thus, these two forms probably survived until the very end of the Maastrichtian in the western Kopet Dagh area. The terminal Maastrichtian ammonite records from the Sumbar River area represent the southeasternmost occurrences of these essentially Boreal taxa.
Dostawca treści:
Biblioteka Nauki
Artykuł

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