Wyniki wyszukiwania

1

Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik

Konodonty z ordowickich głazow narzutowych Polski

100%

Wolska Z.

Acta Palaeontologica Polonica

|

1961

|

tom 06

|

nr 4

Praca poświęcona jest konodontom ordowickim, wypreparowanym za pomocą kwasu octowego z wapiennych głazów narzutowych wieku ordowickiego. W materiale obejmującym około 800 okazów, 497 nadawało się do bliższego oznaczenia. Wyróżniono 33 formy, z których 21 można było dokładnie oznaczyć gatunkowo, pozostałe - w przybliżeniu. Najliczniejsze są gatunki występujące w Szwecji, w ordowiku dolnym, lecz są też takie, których zasięg stratygraficzny jest znacznie szerszy.

2

Primary structure of the connecting ring of ammonoids and its preservation

84%

Kulicki C., Tanabe K., Landman N. H.

Acta Palaeontologica Polonica

|

2007

|

tom 52

|

nr 4

The most distinctive and important element of the hydrostatic organ of ammonoids and nautiloids is the siphuncular tube. It consists of mineral and organic segments (so−called connecting rings). The connecting ring of ammonites never preserves its original organic matter in the mineralized state, usually having undergone diagenetic phosphatisation, more rarely, calcification, or even complete loss. Our knowledge about its original ultrastructure is based upon comparison with Recent Nautilus and phosphatised or calcified ammonite fossils. We show that depending on the taphonomic history, both calcium phosphate and calcite can participate in the diagenesis of the connecting ring wall. Under standard light microscopy, the phosphatised elements are indistinguishable from the calcified ones. Both are dark brown in colour, due to an excess of carbon. The structure of the phosphatised siphuncle does not closely replicate the structure of its organic elements. This casts doubts on conclusions of other authors who described a complex porous structure in ammonite siphuncles, which is completely dissimilar to the siphuncular structure of Recent Nautilus and suggests that this organ functioned differently in ammonites. SEM observations using a BSE detector on the calcified parts of the walls of connecting rings revealed a multilayered structure with perpendicular elements connecting particular layers, resembling the structure of a stacked nacreous layer.

3

Pleistocene foraminifers of the area of the Lower Vistula River (northern Poland)

84%

Brodniewicz I.

Acta Palaeontologica Polonica

|

1972

|

tom 17

|

nr 4

Descriptions of 49 benthic foraminiferal species (including three new species: Elphidium halickii, E. hyalinum and Protelphidium rozkowskae), belonging to 16 genera found in the Pleistocene of the Lower Vistula River area are given. Neither planktonic nor agglutinated foraminifers are represented here. Three assemblages are distinguished: warm-water foraminifer assemblage with contribution of Lusitanian species, found at Brachlewo and related to the Eemian Interglacial, boreal assemblage with contribution of both Lusitanian and Arctic species, found at Elblag, and Arctic assemblage from Nadbrzeże. Foraminiferal fauna from Nadbrzeże shows cyclic alternation of cold-water and warmer-water assemblages corresponding to changes in pollen-spectra. According to pollen analysis, deposits of the Eemian, Amersfoort and Brørup Interglacials are represented at Nadbrzeże.

4

Preservation and variability of Tripartites incisotrilobus (Naumova) emend. and Murospora aurita (Waltz) Playford

84%

Karczewska J., Turnau E.

Acta Palaeontologica Polonica

|

1974

|

tom 19

|

nr 2

Two spore species are newly described on the basis of exceptionally rich and singularly preserved material from the Moscow Basin (Viséan); these are Tripartites (Trilobozonotriletes) incisotrilobus (Naumova), which is emended, and Murospora aurita (Waltz) Playford, the diagnosis of which is extended. The variability of these species and the dependence between the original spore structure and the state of preservation is shown.

5

An Early Triassic gladius associated with soft tissue remains from Idaho, USA-a squid-like coleoid cephalopod at the onset of Mesozoic Era

67%

Doguzhaeva L. A., Brayard A., Goudemand N., Krumenacker L. J., Jenks J. F., Bylund K. G., Fara E., Olivier N., Vennin E., Escarguel G.

Acta Palaeontologica Polonica

|

2018

|

tom 63

|

nr 2

We describe an Olenekian (Early Triassic) “fossil squid” belonging to the oldest complex Mesozoic marine biota collected in the Lower Shale unit of the Lower Triassic Thaynes Group in Idaho, USA. The studied specimen shows a tapered structure embedded in a cylindrical soft body. Morphological, ultrastructural and geochemical features of the specimen suggest that it corresponds to an internally-shelled cephalopod exhibiting a tapered micro-laminated gladius with rachis, narrow median and lateral fields and a large conus; a pair of posterior large fin-supported cartilages and fins; ventral and dorsal mantle band-shape structures, the dorsal one being cartilaginous; mantle patches; a stomach containing undigested arm-hooks and sheet-like pieces of potential flooded ink. Coupled SEM/EDS analyses show that (i) arm-hooks and ink were pseudomorphed by nanoparticles (less than 0.6 mm in diameter) of carbon, (ii) gladius and soft tissues were substituted by granules of calcium phosphate, (iii) cartilage canalicula’s were partially filled with calcium phosphate grains and crystals of Zn- and S-containing minerals. The specimen was hence probably fossilized due to metabolism of P- and C-accumulating bacteria. Based on this specimen, Idahoteuthis parisiana Doguzhaeva and Brayard gen. et sp. nov. and Idahoteuthidae Doguzhaeva and Brayard fam. nov. are erected. This family is characterized by an elongated, cylindrical, dorsally cartilaginous muscular mantle; well-developed, about 0.2 mantle length, rounded anteriorly and acute posteriorly, fin-supported cartilages and similarly shaped two fins at conical mantle termination, and thin slender gladius with narrow median and lateral fields, rachis and breviconic conus. This family assumedly falls in Myopsida (Decabrachia). A streamlined body, large fin-supported cartilages and eroded arm-hooks in the stomach of Idahoteuthis Doguzhaeva and Brayard gen. nov. suggest that this was a maneuverable cannibal predator that dwelled in the subequatorial shallow sea of the west coast of Pangaea.

6

Paedomorphosis and neurocranial ossification in two Devonian lungfishes

59%

Boirot M., Challands T., Cloutier R.

Acta Palaeontologica Polonica

|

2022

|

tom 67

|

nr 2

7

New findings reveal that the Middle Triassic ichthyosaur Mixosaurus cornalianus is the oldest amniote with a dorsal fin

59%

Renesto S., Dal Sasso C., Fogliazza F., Ragni C.

Acta Palaeontologica Polonica

|

2020

|

tom 65

|

nr 3

Ograniczanie wyników

Konodonty z ordowickich głazow narzutowych Polski

Primary structure of the connecting ring of ammonoids and its preservation

Pleistocene foraminifers of the area of the Lower Vistula River (northern Poland)

Preservation and variability of Tripartites incisotrilobus (Naumova) emend. and Murospora aurita (Waltz) Playford

An Early Triassic gladius associated with soft tissue remains from Idaho, USA-a squid-like coleoid cephalopod at the onset of Mesozoic Era

Paedomorphosis and neurocranial ossification in two Devonian lungfishes

New findings reveal that the Middle Triassic ichthyosaur Mixosaurus cornalianus is the oldest amniote with a dorsal fin