Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 7

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  Late Ordovician
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
1
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

Maximizing diductor adhension: An unusual cardinal process in Late Ordovician brachiopods from Estonia

100%
Hints L.
Acta Palaeontologica Polonica
|
2004
|
tom 49
|
nr 4
Cardinal process is a structure on dorsal valve of brachiopods serving for separation or attachment of diductor muscles. A cardinal process with a peculiar folded myophore is described from Late Ordovician “Orthis” kukersiana−group brachiopods assigned to the genus Cyrtonotella (order Orthida). This structure differs from those of other rhynchonelliformean brachiopods and can be considered as a separate type among about twenty varieties of processes described up to now.
2
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

Alleged cnidarian Sphenothallus in the Late Ordovician of Baltica, its mineral composition and microstructure

84%
Vinn O., Kirsimae K.
Acta Palaeontologica Polonica
|
2015
|
tom 60
|
nr 4
Sphenothallus is a problematic fossil with possible cnidarian affinities. Two species of Sphenothallus, S. aff. longissimus and S. kukersianus, occur in the normal marine sediments of the Late Ordovician of Estonia. S. longissimus is more common than S. kukersianus and has a range from early Sandbian to middle Katian. Sphenothallus had a wide paleo-biogeographic distribution in the Late Ordovician. The tubes of Sphenothallus are composed of lamellae with a homogeneous microstructure. The homogeneous microstructure could represent a diagenetic fabric, based on the similarity to diagenetic structures in Torellella (Cnidaria?, Hyolithelminthes). Tubes of Sphenothallus have an apatitic composition, but one tube contains lamellae of diagenetic calcite within the apatitic structure. Sphenothallus presumably had originally biomineralized apatitic tubes. Different lattice parameters of the apatite indicate that biomineralization systems of phosphatic cnidarians Sphenothallus and Conularia sp. may have been different.
3
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

The first evidence of predatory or parasitic drilling in stylophoran echinoderms

84%
Deline B.
Acta Palaeontologica Polonica
|
2008
|
tom 53
|
nr 4
Drillholes are common in many different echinoderm classes, but have yet to be reported in homalozoans. A borehole in the Late Ordovician echinoderm Enoploura is the first evidence of drilling in Stylophora. The level of preservation and environmental setting suggest this drilling occurred while the organism was alive, thus supporting a predatory or parasitic interpretation.
4
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

Late Ordovician brachiopods from the Selety River basin, North Central Kazakhstan

84%
Nikitin I. F., Popov L. E., Bassett M. G.
Acta Palaeontologica Polonica
|
2003
|
tom 48
|
nr 1
A medium−diversity fauna of late Ordovician rhynchonelliformean brachiopods occurs in the Tauken Formation (upper Caradoc–lowermost Ashgill) of north Central Kazakhstan.It demonstrates close similarity to the approximately contemporaneous faunas characteristic of shallow clastic shelves (BA 2–3) of the Chingiz and Chu−Ili ranges (both in Kazakhstan) and South China, but is characterized by a high proportion of endemic new species, including Tetraphalerella bestiubensis sp.nov., Glyptomena kaskolica sp.nov., Dinorthis taukensis sp.nov., Rhynchotrema seletensis sp.nov., and Nalivkinia (Pronalivkinia)zvontsovisp.nov.The abundance of Rhynchotrema is somewhat unusual by comparison with faunas from other Kazakhstanian terranes, where rhynchonellides of the family Ancistrorhynchidae are usually dominant in near−shore biofacies.The occurrence of the atrypides Sulcatospira and early Nalivkinia demonstrates a clear biogeographical linkage with approximately contemporaneous faunas of South China.
5
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

A revision of the Late Ordovician marrellomorph arthropod Furca bohemica from Czech Republic

67%
Rak S., Ortega-Hernandez J., Legg D. A.
Acta Palaeontologica Polonica
|
2013
|
tom 58
|
nr 3
The enigmatic marrellomorph arthropod Furca bohemica from the Upper Ordovician Letná Formation, is redescribed. Based on existing museum specimens and new material collected from the southern slope of Ostrý Hill (Beroun, Czech Republic), the morphology and taphonomy of F. bohemica is reappraised and expanded to produce a new anatomical interpretation. The previously distinct taxa F. pilosa and Furca sp., are synonymised with F. bohemica, the latter being represented by a tapho−series in which decay has obscured some of the diagnostic features. A cladistic analysis indicates close affinities between F. bohemica and the Hunsrück Slate marrellomorph Mimetaster hexagonalis, together forming the Family Mimetasteridae, contrary to previous models for marrellomorph internal relationships. As with other representatives of the group, the overall anatomy of F. bohemica is consistent with a benthic, or possibly nektobenthic, mode of life. The depositional setting of the Letná Formation indicates that F. bohemica inhabited a shallow marine environment, distinguishing it palaeoecologically from all other known marrellomorphs, which have been reported from the continental shelf.
6
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

Concentration of juvenile and small cephalopods in the Hirnantian cherts [Late Ordovician] of Porkuni, Estonia

67%
Kroger B.
Acta Palaeontologica Polonica
|
2007
|
tom 52
|
nr 3
The quarry in the north Estonian village of Porkuni provides a succession of shallow−water limestones and cherts spanning the Ashgillian Normalograptus? extraordinarius graptolite Biozone. This interval comprises the initial pulse of the end−Ordovician extinction. The succession of Porkuni contains abundant and extraordinarily well−preserved fossils. 71 cephalopod specimens were extracted from these strata at Porkuni. Many of these specimens are fragments of juvenile shells or small adults. The embryonic shells of the cephalopods are usually preserved and provide insight into their early ontogeny. The faunal composition is considered as autochthonous and reflects a “palaeo−nursery” in a Hirnantian reef environment. The collected specimens represent twelve genera and four orders. Small oncoceridans and orthoceridans dominate the association. The rate of endemism is very high, since only two genera found in Porkuni, are known from outside Baltoscandia. The new genera Parvihebetoceras, Pomerantsoceras, Porkunioceras, and the new species Parvihebetoceras wahli, Pomerantsoceras tibia, Porkunioceras tuba, and Strandoceras orvikui are erected.
7
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

A new genus of Late Ordovician-Early Silurian pentameride brachiopods and its phylogenetic relationships

67%
Jin J., Popov L. E.
Acta Palaeontologica Polonica
|
2008
|
tom 53
|
nr 2
Protanastrophia repanda gen. et sp. nov. is a reef−dwelling parastrophinid brachiopod in the Lower Silurian (uppermost Telychian) Attawapiskat Formation of the Hudson Bay region of Canada. It is characterized by a small, quasi−smooth shell with gentle anterior costae, a tendency towards an asymmetrical, sigmoidal anterior commissure, and widely separate, subparallel inner hinge plates. Protanastrophia first appeared in the marginal seas of Siberia (Altai, Mongolia) during the Late Ordovician, retaining the primitive character of discrete inner hinge plates in the superfamily Camerelloidea, and preferred a carbonate mound depositional environment. It survived the Late Ordovician mass extinction and subsequently spread to Baltica and Laurentia during Early Silurian (Llandovery) time. Superficially similar asymmetrical shells of Parastrophina portentosa occur in the Upper Ordovician carbonate mound facies of Kazakhstan but differ internally from the new genus in having a septum−supported septalium. Phylogenetic analysis indicates that, within the Camerelloidea, asymmetrical shells with a sigmoidal anterior commissure evolved in Protanastrophia repanda and Parastrophina portentosa independently during the Late Ordovician as a case of homoplasy. The two species belong to separate parastrophinid lineages that evolved in widely separate palaeogeographic regions.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.