Wyniki wyszukiwania - Biblioteka Nauki

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Taxonomic revision of Eocene Antarctic penguins based on tarsometatarsal morphology

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Myrcha A. , Jadwiszczak P. , Tambussi C. P. , Noriega J. I. , Gazdzicki A. , Tatur A. , Del Valle R. A.

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2002

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tom 23

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nr 1

5-46

2

Is cleaning penguins worth the effort? Results from flipper banding

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Whittington P.

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1997

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tom 19

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nr 1-2

3

A new Miocene penguin from Patagonia and its phylogenetic relationships

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Acosta H. C. , Tambussi C. , Donato M. , Cozzuol M.

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tom 52

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nr 2

EN

We describe a new medium−sized penguin, Madrynornis mirandus gen. et sp. nov., from the early late Miocene Puerto Madryn Formation, Chubut Province, Argentina. Although it is evident that extant and fossil penguins form a remarkably homogeneous family of birds, Spheniscidae, their within−group phylogenetic relationships are less obvious. In order to identify the phylogenetic position of the new taxon, we conducted a phylogenetic analysis using 44 osteological characters sampled from 14 representative species of all living genera and five fossil species of Spheniscidae. The family is clearly monophyletic and Madrynornis mirandus is closely related to living taxa. Our phylogenetic interpretation is congruent with biostratigraphic data, with Paraptenodytes from the early Miocene (about 20 Ma) located at the base of the Spheniscidae. Classically, two basic tarsometatarsal types were recognized (one for pre−Miocene and the other for the post−Miocene penguins) based on the pattern of the proximal foramina and the hypotarsus. Madrynornis mirandus exhibits an arrangement of the proximal foramina and a degree of metatarsals fusion similar to that in the living forms, although its elongation index (total length/proximal width) is reminiscent of the extinct Paraptenodytes(a penguin historically recognized as a pre−Miocene form, coming from the early Miocene of Argentina). Madrynornis reveals that the two basic tarsometatarsal types co−existed among Miocene penguins.

4

The oldest fossil record of the extant penguin genus Spheniscus - a new species from the Miocene of Peru

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Gohlich U. B.

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tom 52

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nr 2

EN

Described here is a partial postcranial skeleton and additional disarticulated but associated bones of the new fossil penguin Spheniscus muizonisp. nov. from the latest middle/earliest late Miocene (11–13 Ma) locality of Cerro la Bruja in the Pisco Formation, Peru. This fossil species can be attributed to the extant genus Spheniscus by postcranial morphology and is the oldest known record of this genus. Spheniscus muizonisp. nov. is about the size of the extant Jackass and Magellanic penguins (Spheniscus demersus and Spheniscus magellanicus). Beside Spheniscus urbinai and Spheniscus megaramphus it is the third species of Spheniscus represented in the Pisco Formation. This study contains morphological comparisons with Tertiary penguins of South America and with most of the extant penguin species.

5

Nutrients and cations content in soil solutions from the present and abandoned penguin rookeries [Antarctica, King George Island]

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Juchnowicz-Bierbasz M. , Rakusa-Suszczewski S.

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nr 1

EN

Penguin rookeries are one of the main sources of nutrients for the poor ecosystems of Antarctica. At the current penguin rookeries, and in their vicinity, nitrogen rich ornithogenic soils are formed. Relict ornithogenic soils created at the abandoned rookeries hundreds or even thousands years ago are rich in phosphates. In the region of maritime Antarctica, water plays an important role in distribution and redistribution of nutrients (surface flows and percolation). Soil decomposition processes result in cations and nutrient release. In nutrients originating from relict ornithogenic soils of the Antarctic tundra, phosphates are the dominating elements; while in nutrients originating from contemporary ornithogenic soils nitrogen (mainly ammonia) is the main ingredient. Mineral soils free of penguin influence contain minute amounts of nutrients. Low pH of soil solutions (<4) causes increase of dissolving of phosphate complexes. Near penguin rookery, pH was lowest (2.73-3.33) and intermediate (2.92-3.77) in relict soils. The values of pH were the highest in soil solutions from mineral soil (5.43-7.33). High concentration of cations (mainly K) in soil solutions from the ornithogenic soils and relict ornithogenic soils, suggest their organic (animal) origin.

6

Eocene penguins of Seymour Island, Antarctica: The earliest record, taxonomic problems and some evolutionary considerations

80%

Jadwiszczak P.

Polish Polar Research

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2006

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tom 27

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nr 4

287-302

EN

Penguin bones from the La Meseta Formation (Seymour Island, Antarctic Peninsula) are the only record of Eocene Antarctic Sphenisciformes. Being an abundant component of the youngest unit of the formation (Telm7), they are not so common in earlier strata. Here, I present the oldest penguin remains from the La Meseta Formation (Telm1-Telm2), often bearing close resemblance to their counterparts from younger units. Addressing the recent findings in fossil penguin systematics, I suggest there is too weak a basis for erecting new Eocene Antarctic taxa based on non-tarsometatarsal elements of penguin skeletons, and considering Oligocene species part of the studied assemblage. Finally, I conclude if the common ancestor of extant Sphenisciformes lived in the Eocene Antarctic (as suggested recently), penguins referred to Delphinornis seem to be prime candidates to that position.

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Additions to the lichen flora of Victoria Land, Antarctica

80%

Smykla J. , Krzewicka B. , Wilk K. , Emslie S. D. , Sliwa L.

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nr 2

8

Climate change influences on Antarctic bird populations

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Korczak-Abshire M.

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nr 17

EN

Rapid changes in the major environmental variables like: temperature, wind and precipitation have occurred in the Antarctic region during the last 50 years. In this very sensitive region, even small changes can potentially lead to major environmental perturbations. Then the climate change poses a new challenge to the survival of Antarctic wildlife. As important bioindicators of changes in the ecosystem seabirds and their response to the climate perturbations have been recorded. Atmospheric warming and consequent changes in sea ice conditions have been hypothesized to differentially affect predator populations due to different predator life-history strategies and substantially altered krill recruitment dynamics.