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| Titel |
Plesiosaur-bearing rocks from the Late Cretaceous Tahora Fm, Mangahouanga, New Zealand - a palaeoenvironmental study |
| VerfasserIn |
Vivi Vajda, J. Ian Raine |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250044149
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| Zusammenfassung |
| Mangahouanga Stream, Hawkes Bay, New Zealand is world-famous for its high
southern latitude vertebrate fossils including plesiosaurs, mosasaurs and more rarely,
dinosaurs. The fossils are preserved in the conglomeratic facies of the Maungataniwha
Sandstone Member of the Tahora Formation. A palynological investigation of sediments
from the boulders hosting vertebrate fossils reveals well-preserved palynological
assemblages dominated by pollen and spores from land plants but also including marine
dinoflagellate cysts in one sample. The palynofacies is strongly dominated by wood
fragments including charcoal, and the sample taken from a boulder hosting plesiosaur
vertebrae is entirely terrestrially derived, suggesting a fresh-water habitat for at
least some of these plesiosaurs. The key-pollen taxa Nothofagidites senectus and
Tricolpites lilliei, together with the dinocyst Isabelidinium pellucidum and the megaspore
Grapnelispora evansii, strongly indicate an early Maastrichtian age for the host rock. The
terrestrial palynoflora reflects a mixed vegetation dominated by podocarp conifers and
angiosperms with a significant tree-fern subcanopy component. The presence of
taxa with modern temperate distributions such as Nothofagus (southern beech),
Proteaceae and Cyatheaceae (tree-ferns), indicates a mild-temperate climate and lack of
severe winter freezing during the latest Cretaceous, providing an ecosystem which
most probably made it possible for polar dinosaurs to overwinter. The paper is
dedicated to Mrs Joan Wiffen who with her great persistence, enthusiasm and courage
put Mangahouanga on the world map, becoming a role model for many young
scientists. |
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