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Palaeoecology of the Spathian Virgin Formation (Utah, USA) and its implications for the Early Triassic recovery

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Hofmann R., Hautmann M., Wasmer M., Bucher H.

Acta Palaeontologica Polonica

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2013

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tom 58

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nr 1

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.

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A morganucodontan mammalia form from the Upper Jurassic Morrison Formation, Utah, USA

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Davis B. M., Jager K. R. K., Rougier G. W., Trujillo K., Chamberlain K.

Acta Palaeontologica Polonica

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2022

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tom 67

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nr 1

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Evaluation of the polymerase chain reaction [ PCR ] as a tool for diagnosing infections with the Aleutian mink disease parvovirus [ ADV ] and for discriminating among various ADV isolates

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Bloom M. E., Oie K. L., Wolfinbarger J. B., Durrant G. R.

Zeszyty Naukowe. Przegląd Hodowlany

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1996

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tom 28

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Multituberculate mammals from near the Early-Late Cretaceous boundary, Cedar Mountain Formation, Utah

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Eaton J. G., Cifelli R. L.

Acta Palaeontologica Polonica

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2001

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tom 46

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nr 4

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.

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A revision of the Eleodes (subgenus Caverneleodes) with new species and notes on cave breeding Eleodes (Tenebrionidae: Amphidorini)

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Aalbu R. L., Smith A. D., Triplehorn C. A.

Annales Zoologici

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2012

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tom 62

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nr 2

Subgenus Caverneleodes of the genus Eleodes is diagnosed and revised. Six new species from the United States: California (E. microps); Utah and Northern Arizona (E. wynnei), Central Arizona (E. wheeleri), Southern New Mexico (E. guadalupensis), and Mexico (E. thomasi and E. grutus) are described. The biogeography of the subgenus is discussed. Diagnoses and a key are provided to known species of Caverneleodes. Relationships with other Eleodes are discussed. Cave associated Amphidorini are surveyed.

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A new sauropod dinosaur from the Lower Cretaceous Cedar Mountain Formation, Utah, USA

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Taylor M., Wedel M., Cifelli R.

Acta Palaeontologica Polonica

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2011

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tom 56

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nr 1

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.

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Body size relationships between avian predators and their rodent prey in a North-American sagebrush community

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Gliwicz J.

Acta Ornithologica

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2008

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tom 43

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nr 2

151-158

Larger predators consume prey of greater mean size and include a wider diversity of prey in their diets than their smaller counterparts occurring in the same communities. There is some controversy as to whether these patterns result from opportunistic feeding behavior or from prey size selectivity leading to food-niche segregation among predators. This study examined the effects of body size on the diet of avian predators in the sagebrush habitat of north-eastern Utah. The assessment was based on data collected from the analysis of pellet contents and was deliberately confined to mammalian components, almost exclusively from rodents. A significant positive relationship was found between predator size and both average and maximum prey size, but no such correlation was found for the minimum body size of prey. In general, there was considerable overlap in the rodent prey taken by different raptors, suggesting opportunistic feeding behavior in these predators. However, the size (and species) of rodent prey that contributed most to the consumed biomass was different for each bird species and correlated well with its body size. The revealed pattern of larger raptors acquiring most biomass (energy) from larger prey, implies food selectivity based on its energetic profitability, and niche segregation that could facilitate the coexistence of a high diversity of avian predators in the sagebrush habitat. The possible role of food limitation and competition in the evolution of body size in raptors and the consequences of size-dependent predation are discussed.

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A new species of Microdalyellia [Rhabditophora: Rhabdocoela: Dalyelliidae] from temporal freshwater rock pools in Utah, USA

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Willems W., Artois T., Jocque M., Brendonck L.

Annales Zoologici

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2007

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tom 57

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nr 3

A new species of Microdalyellia Gieysztor, 1938 is described from a temporal freshwater pool in Utah, USA. This new species is characterized by the detailed structure of the stylet, which is of the Microdalyellia-type and consists of a crossbeam that carries two proximal shafts, two distal branches each carrying 5-7 hollow spines, and a median process in between both these spiniferous branches. The most remarkable feature is the presence of a second connection (or crossbeam) between both shafts, giving the proximal part of the stylet the appearance of a plate with a large window. The species’ affinities within the taxon Dalyelliidae Graff, 1905 are discussed. Following the discussion, Gieysztoria rastafariae Therriault and Kolasa, 1999 is transferred to the taxon Microdalyellia, because of the presence of a Microdalyellia-type stylet, which closely resembles that of the newly described species.

Ograniczanie wyników

Palaeoecology of the Spathian Virgin Formation (Utah, USA) and its implications for the Early Triassic recovery

A morganucodontan mammalia form from the Upper Jurassic Morrison Formation, Utah, USA

Evaluation of the polymerase chain reaction [ PCR ] as a tool for diagnosing infections with the Aleutian mink disease parvovirus [ ADV ] and for discriminating among various ADV isolates

Multituberculate mammals from near the Early-Late Cretaceous boundary, Cedar Mountain Formation, Utah

A revision of the Eleodes (subgenus Caverneleodes) with new species and notes on cave breeding Eleodes (Tenebrionidae: Amphidorini)

A new sauropod dinosaur from the Lower Cretaceous Cedar Mountain Formation, Utah, USA

Body size relationships between avian predators and their rodent prey in a North-American sagebrush community

A new species of Microdalyellia [Rhabditophora: Rhabdocoela: Dalyelliidae] from temporal freshwater rock pools in Utah, USA