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Wyszukujesz frazę "Lochkovian" wg kryterium: Temat


Wyświetlanie 1-6 z 6
Tytuł:
New cranial material of the acanthothoracid placoderm Palaeacanthaspis vasta from the Lower Devonian of Podolia—phylogenetic and taxonomic significance
Autorzy:
Dupret, V.
Szaniawski, H.
Dec, M.
Szrek, P.
Powiązania:
https://bibliotekanauki.pl/articles/2082331.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Placodermi
Acanthothoraci
neurocranium
Lochkovian
Devonian
Podolia
Ukraine
Opis:
The Early Devonian vertebrates of Podolia in Ukraine are well known thanks to the material of the basal arthrodire placoderm genus Kujdanowiaspis, originally mentioned by Brotzen in 1934. The anatomical fame of Kujdanowiaspis brought by Erik Stensiö almost eclipsed the presence of the acanthothoracid placoderm Palaeacanthapsis vasta in the underlying beds, with the original material of P. vasta being less well preserved and abundant than that of Kujdanowiaspis. Here we describe a newly discovered specimen of the acanthothoracid P. vasta from the Lochkovian of Podolia (Ukraine). The specimen, although incomplete, is very well preserved in three dimensions and allows a thorough description of its external morphology, which is compared to that of Romundina stellina and other well-known Acanthothoraci. A phylogenetic analysis is performed and the acanthothoracid nature of Palaeacanthaspis is confirmed. However, the position of Palaeacanthaspis within the Acanthothoraci remains uncertain, and its resemblance with Romundina could be due to either synapomorphies or symplesiomorphies. Similarities and differences between the two forms are exposed, and lead to the lack of synonymy at the specific level. Generic synonymy is also questioned for the first time but remains equivocal.
Źródło:
Acta Palaeontologica Polonica; 2021, 66, 2; 337-347
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lochkovian conodonts from Podolia, Ukraine, and their stratigraphic significance
Autorzy:
Drygant, D.
Szaniawski, H.
Powiązania:
https://bibliotekanauki.pl/articles/20977.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Lochkovian
conodont
Podolia
Ukraine
stratigraphy
Conodonta
evolution
Devonian
paleontology
Opis:
In the Podolian Dniester Basin (southwestern Ukraine) the Lower Devonian marine deposits are represented by about 530 m thick continuous sequence of interlaminated carbonate and schale outcrops at several localities. Conodonts occur in most of the carbonate layers of the whole Lochkovian but are not abundant and their ramiform elements are mostly broken or lacking. Therefore, only the pectiniform, Pa elements of twenty five stratigraphically important conodont species occurring in the region are discussed and two new species, Caudicriodus schoenlaubi and Pandorinellina? parva are proposed. The hypothetical phyletic relationships within the main representatives of the icriodontid and spathognathodontid genera, Caudicriodus, Zieglerodina, and Pandorinellina? are traced. Comparison of the previously published and newly obtained data revealed discrepancies in the hitherto used interpretation of some of the conodont taxa and their stratigraphic ranges. Contrary to the earlier reports, Caudicriodus postwoschmidti does not occur in the lower Lochkovian but only in the middle part of the Chortkiv Formation, high above the Monograptus uniformis Zone. Based on new material and verification of the previous determinations, a modified scheme of the Lochkovian conodont zonation in Podolia is proposed. Conodont zones: Caudicriodus hesperius, C. transiens, C. postwoschmidti, C. serus, and ?Caudicriodus steinachensis are distinguished. The zones are correlated with conodont zonations in other regions—Barrandian, Cantabrian Mountains, Pyrenees, and Nevada. Biostratigraphy of the Siluro−Devonian transition and Lochkovian is integrated with the carbon isotope stratigraphy.
Źródło:
Acta Palaeontologica Polonica; 2012, 57, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A redescription of Tesseraspis mosaica Karatajūtė-Talimaa, 1983 (Vertebrata: †Pteraspidomorphi: Heterostraci) from the Lochkovian (Lower Devonian) of Severnaya Zemlya, Russia, with a review of tessellated heterostracan taxa
Autorzy:
Blieck, A.
Elliott, D. K.
Karatajūtė-Talimaa, V. N.
Powiązania:
https://bibliotekanauki.pl/articles/139006.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
tessellated heterostracans
tesseraspidiformes
Lochkovian
Severnaja Zemlja
comparative anatomy
systematic review
heterostraki
lochkovian
lochkov
Severnaya Zemlya
Ziemia Północna
anatomia porównawcza
przegląd literatury
Opis:
Material of tesseraspids (Tesseraspidiformes) is reported from the uppermost Severnaya Zemlya Formation (Lochkovian, Lower Devonian) of the Severnaya Zemlya archipelago, in the Russian Arctic, where it is associated with other vertebrate remains, including corvaspids, acanthodians, and large but rare specimens of osteostracans. The tesseraspid material is not abundant, and most often preserved as a “patchwork” of bony platelets (tesserae), except for a few partly articulated specimens. We redescribe the holotype of Tesseraspis mosaica Karatajūtė-Talimaa, 1983, whose head carapace is preserved as a flattened tube of adjacent tesserae. This material is compared to the already published tesseraspid taxa, i.e., T. tessellata Wills, 1935, T. toombsi Tarlo, 1964, T. mutabilis (Brotzen, 1934), T. oervigi Tarlo, 1964 emend. Dineley and Loeffler, 1976, T. denisoni Tarlo, 1964, and T. talimaae Tarlo, 1965. All species are based upon rare and incomplete material, as no head carapaces associated with trunk and tail are known, and so, the intraspecific variability is also unknown. Distinction between “species” is based on the detail of the superficial sculpture of the tesserae of the head carapaces, which is unsatisfactory. It is concluded that only four of the nominal species can be retained. A review of all other known tessellated pteraspidomorphs indicates that our knowledge of tessellated heterostracans is currently insufficient to support a meaningful classification.
Źródło:
Acta Geologica Polonica; 2018, 68, 3; 275-306
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Early Devonian ischnacanthiform acanthodian Ischnacanthus gracilis (Egerton, 1861) from the Midland Valley of Scotland
Autorzy:
Burrow, C. J.
Newman, M.
den Blaauwen, J.
Jones, R.
Davidson, R.
Powiązania:
https://bibliotekanauki.pl/articles/139010.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Acanthodii
Ischnacanthus
Lochkovian
palaeohistology
dentition
fałdopłetwe
akantody
lochkov
dewon wczesny
paleohistologia
uzębienie
Opis:
Ischnacanthus gracilis (Egerton, 1861), the only ischnacanthiform acanthodian from the Lochkovian Lower Old Red Sandstone of Scotland, is known from hundreds of specimens in institutional collections worldwide. Despite this relative abundance, morphology and histology of its skeletal elements have rarely been investigated. Surface details of spines, dental elements, and scales are often not visible in specimens because they are usually split through the middle. We have examined a broad size range of fish, from 35 mm to 250 mm long. Several intact (not split) specimens have been collected in recent years and acid-prepared to show fine details of the dermal and dental elements. We have also used scanning electron microscopy of scales, jaws and dental elements, denticles and fin spines, and serial thin sectioning of articulated specimens, to document their structure. Some of our notable observations include: identification of ventral lateral lines, double-layered subtessellate calcified cartilage forming the jaws, and the probable occurrence of extraoral tricuspid denticles on the jaws of most fish. Examination of the size range, body proportions and dentition of institutional specimens gives no support for recognising more than one species in the Midland Valley localities.
Źródło:
Acta Geologica Polonica; 2018, 68, 3; 335-362
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lanea carlsi conodont apparatus reconstruction and its significance for subdivision of the Lochkovian
Autorzy:
Slavik, L.
Powiązania:
https://bibliotekanauki.pl/articles/20418.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Lanea carlsi
conodont
apparatus reconstruction
significance
Lochkovian
Conodonta
taxonomy
phylogenesis
biostratigraphy
Barrandian
Opis:
A cosmopolitan spathognathodontid taxon “Ancyrodelloides carlsi” is not regarded in this paper as one of the earliest known representatives of Ancyrodelloides according to former concepts, but is considered as conspicuous member of the genus Lanea. The taxon shows distinct morphological innovation of the upper surface of the Pa element within the Lanea lineage which makes it easily recognizable worldwide and suitable for global correlation. Presented stratigraphic correlation using conodonts and other faunal groups qualifies a short−lived Lanea carlsi as probably the best marker of the middle Lochkovian base. This paper presents reconstruction of the apparatus of L. carlsi which is the first complete reconstruction in the genus Lanea. The comparison of the Lanea apparatus and assumed apparatus of early Ancyrodelloides from the Požáry Quarries (Barrandian, Czech Republic) resulted to proposal of an alternative concept of evolution of these two genera. The relatively short−lived genus Ancyrodelloides is considered to split off from the Lanea clade in the late middle Lochkovian by the entry of Ancncyrodelloides transitans.
Źródło:
Acta Palaeontologica Polonica; 2011, 56, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stem chondrichthyan microfossils from the Lower Old Red Sandstone of the Welsh Borderland
Autorzy:
Burrow, C. J.
Turner, S.
Powiązania:
https://bibliotekanauki.pl/articles/138801.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
scale histology
palaeobiogeography
Lower Devonian
Lochkovian
stem gnatho stomes
Altholepis
Polymerolepis
British Isles
histologia
paleobiogeografia
dewon dolny
lochkov
Wyspy Brytyjskie
Opis:
Placoid and polyodontode scales of stem chondrichthyans have been found in the early Lochkovian “Ditton Group” of the Brown Clee Hill district, Shropshire, England and at Talgarth, south Wales. One of the forms is assigned to a new species of Altholepis Karatajūtė-Talimaa, 1997, a genus already recognised from Lochkovian shallow marine deposits in Celtiberia, Spain and the Northwest Territories, Canada as well as the type locality in Podolia, Ukraine. Altholepis salopensis sp. nov. is based on small polyodontode scales with typically three to eight high odontodes; the scale form was previously considered to belong to acanthodian “Nostolepis” robusta (Brotzen, 1934). The structure of other scales formerly assigned to “Nostolepis” robusta has led us to erect a new genus Jolepis for this scale form, which differs from Altholepis in lacking an ordered layout of odontodes. Jolepis robusta (Brotzen, 1934), originally (and possibly still) considered to be an acanthodian, is also known from the Baltic countries, Russia, and northern Germany (ex erratic limestones). Scales of acanthodian Parexus recurvus Agassiz, 1845, and/or possibly from the stem chondrichthyan Seretolepis elegans Karatajūtė-Talimaa, 1968 (scales of these two taxa are barely distinguishable), and of stem chondrichthyan Polymerolepis whitei Karatajūtė-Talimaa, 1968 are also present. Altholepis, Jolepis gen. nov., Seretolepis Karatajūtė-Talimaa, 1968 and Polymerolepis KaratajūtėTalimaa, 1968 are found in marine deposits elsewhere; the British occurrence of these taxa adds to the debate on the sedimentological origins of the Lower Old Red Sandstone deposits in the Welsh Borderland. The geographic range of several early sharks is now known to extend around the Old Red Sandstone continent and beyond.
Źródło:
Acta Geologica Polonica; 2018, 68, 3; 321-334
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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