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Wyszukujesz frazę "small body size" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
Palaeoecology of tropical marine invertebrate assemblages from the Late Triassic of Misurina, Dolomites, Italy
Autorzy:
Hausmann, I.M.
Nutzel, A.
Roden, V.J.
Reich, M.
Powiązania:
https://bibliotekanauki.pl/articles/2082303.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Mollusca
Echinodermata
diversity
small body size
Ladinian
Carnian
Cassian Formation
Alps
Opis:
Two marine invertebrate fossil assemblages from the Late Triassic Cassian Formation (Dolomites, northern Italy) were examined to assess their diversity and palaeoecology. Surface and bulk samples from the localities Misurina Landslide and Lago Antorno were taken and analysed separately. Both benthic assemblages are relatively similar in taxonomic composition. Gastropods form the most abundant and diverse group, followed by bivalves. Disarticulated echinoderm ossicles are also common in the bulk sample from Misurina Landslide, but they are rare at Lago Antorno. The Misurina Landslide outcrop has yielded two echinoderm Palaeozoic holdovers, the ophiocistioid Linguaserra triassica and plates of putative proterocidarids, supporting the earlier hypothesis that such basins acted as refugia. The gastropod species Coelostylina conica, Prostylifer paludinaris, and Ampezzopleura hybridopsis are characteristic elements of both assemblages. The gastropod Jurilda elongata, however, is the most abundant species at Misurina Landslide, whereas juveniles of the gastropod species Dentineritaria neritina dominate the assemblage from Lago Antorno. Newly described gastropod taxa are Angulatella bizzarinii Nützel and Hausmann gen. et sp. nov., Bandellina compacta Nützel and Hausmann sp. nov., and Ampezzogyra angulata Nützel and Hausmann sp. nov. Fifty-seven invertebrate species were found in the bulk sample from Misurina Landslide and 26 species were recovered from the bulk sample from Lago Antorno. However, sample size from Lago Antorno was much smaller than that from Misurina. Diversity indices (Shannon, Simpson, Berger-Parker) show similar moderate diversities in both assemblages. Rarefaction curves and rank-abundance distributions also point to very similar diversities and ecological structures of the fossil assemblages. Both assemblages are autochthonous or parautochthonous, stemming from basinal, soft-bottom habitats. Their taxonomic composition differs significantly from that of other faunas known from the Cassian Formation. The tropical marine Cassian palaeoecosystem was highly complex and its diversity is still far from being fully explored.
Źródło:
Acta Palaeontologica Polonica; 2021, 66, 1; 143-192
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Postcranial osteology of the first early-stage juvenile skeleton of Plateosaurus trossingensis from the Norian of Frick, Switzerland
Autorzy:
Nau, D.
Lallensack, J.N.
Bachmann, U.
Sander, P.M.
Powiązania:
https://bibliotekanauki.pl/articles/2082237.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Dinosauria
Sauropodomorpha
morphometrics
morphology
small body size
early ontogeny
Triassic
Swiss Plateau
Opis:
Owing to monospecific mass-accumulation sites in Central Europe, the early-branching sauropodomorph Plateosaurus has one of the best fossil records among dinosaurs. Despite this, early-stage juveniles have been conspicuously absent. However, such specimens are critical in assessing the ontogenetic development of this taxon, as well as the role of heterochrony in sauropodomorph evolution. A new skeleton from the Plateosaurus bonebed at the Gruhalde Quarry (Klettgau Formation, Norian) of Frick, Switzerland, nicknamed “Fabian”, represents the first substantially complete juvenile referrable to Plateosaurus. The specimen includes large portions of the cranium and vertebral column and an almost completely represented appendicular skeleton. Its juvenile ontogenetic stage is confirmed by a lack of neurocentral suture fusion in the axial skeleton. Consistent with this, the estimated total length and body mass of approximately of 2.3 m and 40 kg are considerably smaller than any previously reported specimen of the genus. Surprisingly, the postcranial morphology of the specimen is remarkably consistent with that of osteologically mature individuals, including a virtually fully developed pattern of laminae and fossae in the vertebrae. Comparisons of body proportions are complicated by varying degrees of compaction in the limb elements, but skeletal proportions mostly appear to follow isometry, with the notable exceptions of a relatively long neck, proportionately larger manus, shorter, more gracile humerus and shorter forearm in the juvenile specimen. The observed morphology suggests that adult morphology was either achieved early in ontogeny of Plateosaurus, or alternatively that developmental plasticity, which has previously been found to result in high variability of adult body size, could potentially also extend to morphological development.
Źródło:
Acta Palaeontologica Polonica; 2020, 65, 4; 679-708
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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