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Wyszukujesz frazę "ammonoidea" wg kryterium: Temat


Wyświetlanie 1-4 z 4
Tytuł:
Virtual 3D modeling of the ammonoid conch to study its hydrostatic properties
Autorzy:
Moron-Alfonso, D.A.
Peterman, D.J.
Cichowolski, M.
Hoffmann, R.
Lemanis, R.E.
Powiązania:
https://bibliotekanauki.pl/articles/2082232.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Cephalopoda
Ammonoidea
virtual modeling
3D
conch
CT-scan
morphometry
Cretaceous
Antarctica
Opis:
Computed tomography has provided a wealth of biological data that now stands beside a vast, more traditional, morphometric database. By exploiting these two resources, we present a novel methodology to construct intricate, virtual cephalopod shells. As a case of study, we applied this method to Maorites seymourianus using data obtained from a previous work. For this purpose, evaluation of the conch geometry, and the definition of new parameters such as the segment width expansion rate (SWER), segment height expansion rate (SHER), the segment thickness expansion rate (STER), and three indices related, were introduced. The conch geometry of M. seymourianus follows a spiral that can be defined by a polynomial function. While similar to a logarithmic function, a polynomial fit is preferred because it reveals higher values of whorl expansion at the early ontogenetic phase and lower values reaching the adult body chamber. Results on the hydrostatic properties of the virtual models indicate that M. seymourianus would have a near neutral buoyancy, ranging from slightly positive to slightly negative, depending upon parameters that influence organismal mass. Positions of the center of mass and the center of buoyancy indicate that the studied species would have a relatively low hydrostatic stability, estimating a shell orientation of approximately 74–76° with respect to the vertical, with the aperture slightly inclined downwards relative to the horizontal plain.
Źródło:
Acta Palaeontologica Polonica; 2020, 65, 3; 467-480
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Size-shape relationships in the Mesozoic planispiral ammonites
Autorzy:
Parent, H.
Greco, A.F.
Bejas, M.
Powiązania:
https://bibliotekanauki.pl/articles/19942.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
size-shape relationship
Mesozoic
planispiral ammonite
ammonite
Ammonoidea
shell
Cephalopoda
paleontology
marine fossil
Opis:
Ammonites are of outstanding importance in dating events of the Mesozoic and in the study of mechanisms, modes and timing of evolutionary processes. These applications rely on a detailed understanding of their morphology and the modes of variation. It has been known for a long time that their shape is composed of a number of highly correlated features. A new model, called the ADA−model, is introduced for the study of shell morphology (size and shape). The new model is based on classic dimensions which are stable parameters throughout ontogeny, giving very close agreement between pre− dictions and actual observations. It was applied in the exploration of the morphospace occupied by the planispirally coiled and the regularly uncoiled Mesozoic Ammonoidea, based on two new reduced morphospaces introduced for the analysis. Results obtained expose close relationships between size and shape, and general patterns in the ammonite shell morphol− ogy and morphogenesis. (i) The relative apertural height of the whorl section relative to the diameter of the shell (H₂/D) is involved in definition of size and shape. (ii) This same dimension shows a strong tendency to be H₂/D = 0.3. (iii) There are some geometrically possible shell shapes (or morphotypes) which seem to have not been developed since they are not known in the current record. Assuming the known ranges of protoconch size and whorl number as constraints, the ADA−model strongly suggests that these morphotypes have not been developed for the too large or too small sizes the shells would have attained, well outside of the actual size range of the planispirally coiled Ammonoidea. (iv) The law of covariation is shown to be a general pattern within the planispiral ammonites which describes structured variation of the shell shape. (v) A large fraction of the non−structured variation seems originate in the lack of correlation between the rela− tive umbilical diameter and width of the whorl section.
Źródło:
Acta Palaeontologica Polonica; 2010, 55, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aalenian (Jurassic) to Berriasian (Cretaceous) chronostratigraphic zonation and guide ammonites of the Central Andes (Argentina, Chile, Peru)
Autorzy:
Parent, Horacio
Powiązania:
https://bibliotekanauki.pl/articles/2204237.pdf
Data publikacji:
2022
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Neuquén Basin
Tarapacá Basin
chronostratigraphy
zonation
biohorizons
Ammonoidea
Cephalopoda
Aalenian to Berriasian
Basen Neuquén
Kotlina Tarapacá
chronostratygrafia
podział na strefy
biohoryzont
głowonogi
Opis:
In the Central Andes there are developed two marine basins with an extensive Jurassic record: the Neuquén (or Central Andean) Basin and the Tarapacá Basin. Their Jurassic and Lower Cretaceous ammonite successions have been studied extensively for more than 150 years, producing detailed chronostratigraphic scales based on ammonite zones and biohorizons. The ammonite faunas include Andean lineages, and cosmopolitan, Tethyan, Caribbean, North American, and Indo-Madagascan elements. This paper presents the results of a revision of the zonation of the interval Aalenian-Berriasian. Before presenting the results, this paper emphasizes the distinction between, and the convenient nomenclature for, biozones, zones, standard zones, and biohorizons. The scissum Hz. (new) is introduced in the lower (-most?) Manflasensis Zone (Aalenian). The Rotundum Subzone (new) with base at the cf.-leptus Hz., is introduced for the upper part of the Rotundum Zone (Bajocian). The Gulisanoi Zone (Bathonian) is standardized by designation of the cf.-aspidoides Hz. (new) as its base. The Chacaymelehuensis Zone (new) with base at the “prahecquense” Hz. (new) is introduced for the Callovian. The Cubanensis Zone (Oxfordian) is introduced to replace nominally, or to rename, the inconveniently named “Passendorferia” Zone. The Tarapacaense Zone (Oxfordian) is standardized by designation of the tarapacaense Hz. (new) as its base. The Tithonian Malarguensis Zone (formerly subzone) is here emended and standardized by designation of the malarguensis Hz. as its base; this zone replaces the unviable Mendozanus Zone. The Zitteli Zone is standardized by designation of the widely recorded perlaevis Hz. as its base. The Fascipartita Subzone (Internispinosum Zone) is standardized by designation of the internispinosum-beta Hz. (new) as its base. The Alternans Zone is standardized by designation of the vetustum Hz. as its base, and the Koeneni Zone (uppermost Tithonian) by designation of the striolatus Hz. as its base.
Źródło:
Volumina Jurassica; 2022, 20; 1--46
1896-7876
1731-3708
Pojawia się w:
Volumina Jurassica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Extreme abundance of ammonoids in mass accumulations from the Late Devonian of the Moroccan Anti-Atlas
Autorzy:
Greif, M.
Nebelsick, J.H.
Klug, C.
Powiązania:
https://bibliotekanauki.pl/articles/31341387.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
paleoecology
ammonoid
mass accumulation
biomass
Cephalopoda
Ammonoidea
fecundity
Famennian
Devonian
Late Devonian
Morocco
Anti-Atlas Mountains
Lesser Atlas Mountains zob.Anti-Atlas Mountains
Little Atlas Mountains zob.Anti-Atlas Mountains
Atlas Mountains
Źródło:
Acta Palaeontologica Polonica; 2022, 67, 3; 667-684
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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