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Wyszukujesz frazę "toxodontidae" wg kryterium: Temat


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Tytuł:
New postcranial remains of large toxodontian notoungulates from the late Oligocene of Mendoza, Argentina and their systematic implications
Autorzy:
DEL PINO, SANTIAGO HERNÁNDEZ
SEOANE, FEDERICO D.
CERDEÑO, ESPERANZA
Powiązania:
https://bibliotekanauki.pl/articles/945282.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
mammalia
toxodontidae
leontiniidae
homalodotheriidae
postcranium
deseadan age
argentina
mendoza
Opis:
During the last decade, the Deseadan (late Oligocene) Quebrada Fiera locality, Mendoza Province, Argentina, has provided a large amount of mammal remains. Taxonomic studies have shown the presence of faunal elements common with other Deseadan associations from Patagonia and lower latitudes (Salla, Bolivia), as well as endemic taxa of different groups of mammals (Notohippidae, Leontiniidae, Homalodotheriidae, Hegetotheriidae, and Metatheria) and even a gastropod. In this work, we present a taxonomic and phylogenetic analysis of a set of postcranial fossils of three families of the suborder Toxodontia (Notoungulata). The postcranial elements are assigned to taxa previously recognized at Quebrada Fiera, such as the leontiniid Gualta cuyana and the homalodotheriid Asmodeus petrasnerus, but also to the family Toxodontidae that is represented by Proadinotherium sp. and another larger toxodontid; a few dental remains of Proadinotherium are also included as this is the first time that toxodontids from Quebrada Fiera are described. In the case of A. petrasnerus, an almost complete calcaneum allows us to expand the diagnosis of this taxon. The bones assigned to G. cuyana enlarge the anatomical knowledge of this species. In turn, the presence of the genus Proadinotherium extends its geographic distribution in Argentina and adds to the extra-Patagonian record of P. saltoni from Salla, Bolivia. Phylogenetic results do not differ much from previous analyses using postcranial characters, and the obtained consensus trees show low node supports. The various phylogenetic analyses performed here provide a more robust framework to interpret the relationships of the studied taxa.
Źródło:
Acta Palaeontologica Polonica; 2017, 62, 1; 195-210
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enamel microstructure of permanent and deciduous teeth of a species of notoungulate Toxodon : Development, functional, and evolutionary implications
Autorzy:
Braunn, Patrícia R.
Ferigolo, Jorge
Ribeiro, Ana M.
Powiązania:
https://bibliotekanauki.pl/articles/2216330.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Mammalia
Toxodontidae
euhypsodont teeth
enamel-dentine junction
Hunter-Schreger bands
Pleistocene
Brazil
neonatal line
Opis:
Enamel microstructure is studied here in Toxodon sp., a notoungulate from the Pleistocene of South America. The material includes 13 specimens from outcrops in São Paulo and Rio Grande do Sul states, Brazil. Analyses of ground sections of upper and lower incisors, premolars, molars, and deciduous premolars by scanning electron microscopy reveal Schmelzmuster with three enamel types: modified radial enamel (MRE), associated with the enameldentine junction (EDJ); Hunter Schreger bands (HSB), an intermediary layer with decussating prisms; and radial enamel (RE), a layer placed next to the outer enamel surface. Microstructural features vary in each tooth category, on the buccal and lingual sides, as well as in the different regions of each tooth. The proportion of RE increases in the occlusal area of I2, which commonly exhibits intense wear, and may be related to abrasion resistance. HSB thickness ranges from 6 to 20 prisms, with the thickest portions placed in areas with intense masticatory loads. The most concentrated packing densities of HSB in the upper incisors and lower premolars suggest these teeth bore the greatest biomechanical demands. Incisors and cheek teeth show differentiation of Schmelzmuster, suggesting dental antagonistic contact areas, as well as leading and trailing edges. Deciduous premolars exhibit enamel in the early stages of development, and a neonatal line is observed almost parallel to the EDJ, possibly related to biological stress during birth. The EDJ is scalloped in all dental categories, with varying sizes and shapes. Larger and more pronounced scallops are observed in I2, i3, p4, and in the enamel folds of the upper and lower cheek teeth, associated with microstructural features indicative of greater biomechanical demands. Microstructural enamel findings presented here corroborate morphological trends in the dentition of Notoungulata related to hypsodonty, providing greater resistance to the consumption of abrasive diets in these euhypsodont-toothed herbivores.
Źródło:
Acta Palaeontologica Polonica; 2021, 66, 2; 449-464
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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