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Wyświetlanie 1-5 z 5
Tytuł:
A new occurrence of Dakotasuchus kingi from the Late Cretaceous of Utah, USA, and the diagnostic utility of postcranial characters in Crocodyliformes
Autorzy:
FREDERICKSON, JOSEPH A.
COHEN, JOSHUA E.
HUNT, TYLER C.
CIFELLI, RICHARD L.
Powiązania:
https://bibliotekanauki.pl/articles/945241.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
crocodylomorpha
goniopholididae
dakotasuchus
cretaceous
cenomanian
utah
mussentuchit
Opis:
Cenomanian mesoeucrocodylians from North America are known primarily from isolated teeth and scutes; any associated remains of this age are noteworthy and represent welcome additions to knowledge. Herein, we describe postcranial elements belonging to a single individual goniopholidid from the Mussentuchit Member of the Cedar Mountain Formation. We argue that this individual represents only the second fossil referable to Dakotasuchus kingi, based on overlapping elements, such as the coracoid, dorsal vertebrae, and scutes, which are strikingly similar to their counterparts in the holotype. The coracoid, in particular, is readily distinguished from those belonging to other closely-related crocodilian taxa; enough so to warrant detailed comparisons in the absence of diagnostic cranial material. The new D. kingi specimen is nearly 20% larger than the holotype, with body length and mass estimates comparable to modern American alligators (Alligator mississippiensis), making it one of the largest aquatic predators in the Mussentuchit ecosystem.
Źródło:
Acta Palaeontologica Polonica; 2017, 62, 2; 279-286
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multituberculate mammals from near the Early-Late Cretaceous boundary, Cedar Mountain Formation, Utah
Autorzy:
Eaton, J G
Cifelli, R.L.
Powiązania:
https://bibliotekanauki.pl/articles/20067.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
multituberculate
Utah
mammal
Cretaceous
Cedar Mountain Formation
Multituberculata
North America
multituberculate mammal
paleontology
Cimolodonta
Opis:
Herein we describe the oldest well-sampled multituberculate assemblage from the Cretaceous of North America. The fauna is dated at 98.37 Ma and thus approximates the Albian-Cenomanian (Early-Late Cretaceous) boundary. The multituberculate fauna is diverse. Two of the multituberculates (Janumys erebos gen. et sp. n. and an unidentified taxon) are provisionally placed among 'Plagiaulacida'. Another taxon, Ameribaatar zofiae gen. et sp. n., is of uncertain subordinal affinities. The remaining multituberculates appear to represent the advanced suborder Cimolodonta and fall within the 'Paracimexomys group'. We rediagnose Paracimexomys on the basis of the type species, P. priscus, and refer to other species as cf. Paracimexomys (including cf. P. perplexus sp. n.). A revised diagnosis is also provided for Cenomanian Dakotamys. A previously-described species from the Cedar Mountain Formation is placed in Cedaromys gen. n. as C. bestia, together with C. pawus sp. n. Bryceomys is represented in the fauna by B. intermedius sp. n. Relationships of Paracimexomys-group to later taxa remain obscure. However, Bryceomys and Cedaromys share a number of features with Cimolodontidae. Given these resemblances, together with the fact that Cimolodontidae retain certain plesiomorphies (stout lower incisor, gigantoprismatic enamel) with respect to Ptilodontoidea (to which they are commonly referred), we suggest that Cimolodontidae may have arisen from a clade within the 'Paracimexomys group', independent of ptilodontoids.
W pracy opisano najstarszy dobrze opróbowany zespół zębów wieloguzkowców (Multituberculata) z kredy Ameryki Północnej. Fauna formacji Cedar Mountain jest datowana na 98,37 mln lat temu, a więc pochodzi mniej więcej z granicy albu i cenomanu (a więc przełomu wczesnej i późnej kredy). Fauna wieloguzkowców jest zróżnicowana. Dwa z nich (Janumys erebos gen. et sp. n. oraz nieoznaczony takson) tymczasowo zaliczono do ,,Plagiaulacida". Kolejny takson, Ameribaatar zofiae gen. et sp. n., ma niejasną przynależność na szczeblu podrzędu. Wydaje się, że pozostałe wieloguzkowce reprezentują, zaawansowany podrząd Cimolodonta i należałoby je umieścić w ,,grupie Paracimexomys". Diagnoza Paracimexomys została zrewidowana na podstawie gatunku typowego, P. priscus, toteż inne gatunki potraktowano jako cf. Paracimexomys (w tym cf. P. perplexus sp. n.). Zrewidowaną diagnozę uzyskał także cenomański Dakotamys. Opisany juz wcześniej z formacji Cedar Mountain gatunek umieszczony został w nowym rdozaju Cedaromys jako C. bestia, obok C. parvus sp. n. Bryceomys reprezentowany jest w opisywanej faunie przez B. intermedius sp. n. Niejasne pozostają pokrewieństwa między grupą Paracimexomys a późniejszymi taksonami. Bryceomys i Cedaromys mają jednak wiele cech wspólnych z rodziną Cimolodontidae. Ze względu na owe podobieństwa, a także na zachowanie przez Cimolodontidae pewnych plezjomorfii (masywny dolny siekacz, gigantopryzmatczne szkliwo) nieobecnych u Ptilodontoidea (do których się je zwykle zalicza), sugerujemy, ze Cimolodontidae mogły się wyodrębnić z kladu w obrębie ,,grupy Paracimexomys", niezależnie od ptilodontoidów.
Źródło:
Acta Palaeontologica Polonica; 2001, 46, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Palaeoecology of the Spathian Virgin Formation (Utah, USA) and its implications for the Early Triassic recovery
Autorzy:
Hofmann, R.
Hautmann, M.
Wasmer, M.
Bucher, H.
Powiązania:
https://bibliotekanauki.pl/articles/21319.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleoecology
Spathian Virgin Formation
Utah
USA
Early Triassic
Triassic
recovery
diversity
biotic recovery
mass extinction
Opis:
The Spathian (late Early Triassic) Virgin Formation of south−western Utah (USA) yields a comparatively diverse benthic fauna that flourished ~2 Ma after the end−Permian mass extinction. In this study, we present quantitative palaeoecological data, which are analysed in the context of depositional environments. This integrated approach helps to discriminate between effects of the end−Permian mass extinction event and local environmental factors on alpha diversity and ecological structure of the Virgin Fauna. Shallow subtidal environments yield the highest species richness and lowest dominance val− ues as recorded in two benthic associations, the Eumorphotis ericiusAssociation and the Protogusarella smithi Association, both ofwhich contain 20 benthic species (bivalves, gastropods, brachiopods, echinoderms, and porifers). Tidal inlet deposits yield a low diverse fauna (Piarorhynchella triassica Association) with a very high dominance of filter feeders adapted to high energy conditions.Another comparably low diverse fauna is recorded by the Bakevellia exporrecta Association, which occurs in deposits of the offshore transition zone,most likely reflecting unconsolidated substrates. A single sample contain− ing five bivalve species (Bakevellia costata Assemblage) is recorded from a marginal−marine setting. The Virgin fauna yields a bulk diversity of 30 benthic species (22 genera) of body fossils and 14 ichnogenera and, thus, represents the most di− verse marine bottom fauna known so far from the Early Triassic. Our results suggest that oceanographic conditions during the early Spathian enabled ecosystems to rediversify without major abiotic limitations. However, taxonomical differentia− tion between habitats was still low, indicating a time lag between increasing within−habitat diversity (alpha diversity) and the onset of taxonomical differentiation between habitats (beta diversity). We suggest that taxonomical habitat differentia− tion after mass extinction events starts only when within−habitat competition exceeds a certain threshold, which was not yet reached in the Spathian of the investigated area. This interpretation is an alternative to previous suggestions that the preva− lence of generalistic taxa in the aftermath of mass extinction events reflects protracted environmental stress. The onset of in− creasing beta diversity is a potential criterion for distinguishing two major recovery phases, the first ending with habitat satu− ration and the second ending with the completion of ecosystem differentiation.
Źródło:
Acta Palaeontologica Polonica; 2013, 58, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new sauropod dinosaur from the Lower Cretaceous Cedar Mountain Formation, Utah, USA
Autorzy:
Taylor, M.
Wedel, M.
Cifelli, R.
Powiązania:
https://bibliotekanauki.pl/articles/23198.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
Dinosauria
Sauropoda
Camarasauromorpha
Brontomerus
Brontomerus mcintoshi
diversity
Early Cretaceous
North America
new sauropod dinosaur
Lower Cretaceous
Cedar Mountain Formation
Utah
Cretaceous
sauropod dinosaur
Opis:
Brontomerus mcintoshi is a new genus and species of sauropod dinosaur from the Hotel Mesa Quarry in Grand County, Utah, USA, in the upper part of the Ruby Ranch Member (Aptian–Albian) of the Lower Cretaceous Cedar Mountain Formation. It is known from at least two fragmentary specimens of different sizes. The type specimen is OMNH 66430, the left ilium of a juvenile individual; tentatively referred specimens include a crushed presacral centrum, a complete and well−preserved mid−to−posterior caudal vertebra, the partial centrum of a distal caudal vertebra, a complete pneumatic anterior dorsal rib from the right side, the nearly complete left scapula of a much larger, presumably adult, individual, and two partial sternal plates. Brontomerus is diagnosed by five autapomorphies of the type specimen: preacetabular lobe 55% of total ilium length, longer than in any other sauropod; preacetabular lobe directed anterolaterally at 30 to the sagittal, but straight in dorsal view and vertically oriented; postacetabular lobe reduced to near absence; ischiadic peduncle reduced to very low bulge; ilium proportionally taller than in any other sauropod, 52% as high as long. In a phylogenetic analysis, Brontomerus was recovered as a camarasauromorph in all most parsimonious trees, but with uncertain position within that clade. The large preacetabular lobe of the ilium anchored powerful protractor and abductor muscles, but precise interpretation is impossible without functionally related elements such as femora and proximal caudal vertebrae. Brontomerus is the eighth sauropod genus named from the Early Cretaceous of North America, and more remain to be described: North American sauropod diversity did not decline catastrophically at the end of the Jurassic as often assumed. The most striking differences between Late Jurassic and Early Cretaceous sauropod faunas in North America is that the former are abundant and dominated by diplodocids, whereas the latter are comparatively scarce— though still diverse—and dominated by macronarians.
Źródło:
Acta Palaeontologica Polonica; 2011, 56, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Crouching theropod and Navahopus sauropodomorph tracks from the Early Jurassic Navajo Sandstone of USA
Autorzy:
Milan, J
Loope, D.B.
Bromley, R.G.
Powiązania:
https://bibliotekanauki.pl/articles/21900.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Navajo Sandstone Formation
Navahopus coyoteensis
Early Jurassic
crouching trace
paleontology
Navahopodidae
sauropodomorph track
ichnology
Southern Utah
USA
theropod dinosaur
Theropoda
trackway
locomotory habit
Sauropodomorpha
Navahopus
Jurassic
Northern Arizona
remains
theropod track
Opis:
Numerous tracks and trackways are preserved in the a cross−strata of the Lower Jurassic Navajo Sandstone of northern Arizona and southern Utah, USA. Tracks and trackways of small theropod dinosaurs are particularly abundant within one 10−m−thick interval. This paper describes a crouching trace from a theropod dinosaur that shows impressions of all four limbs, the ischial callosity, the tail, and tracks leading to and away from the crouching site, and revises the interpretation of a well preserved trackway hitherto referred to the synapsid ichnogenus Brasilichnium and here considered to be from a sauropodomorph dinosaur. It is named Navahopus coyoteensisisp. nov. on the basis of morphological differences from the type ichnospecies N. falcipollex. The ichnofamily Navahopodidae is revised to include Tetrasauropous unguiferus, Navahopus falcipollex, and N. coyoteensis.
Źródło:
Acta Palaeontologica Polonica; 2008, 53, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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