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| Titel |
Mammal faunal change in the zone of the Paleogene hyperthermals ETM2 and H2 |
| VerfasserIn |
A. E. Chew |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 11, no. 9 ; Nr. 11, no. 9 (2015-09-24), S.1223-1237 |
| Datensatznummer |
250117406
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| Publikation (Nr.) |
 copernicus.org/cp-11-1223-2015.pdf |
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| Zusammenfassung |
| "Hyperthermals" are past intervals of geologically rapid global warming
that provide the opportunity to study the effects of climate change on
existing faunas over thousands of years. A series of hyperthermals is known
from the early Eocene (~ 56–54 million years ago), including the
Paleocene–Eocene Thermal Maximum (PETM) and two subsequent hyperthermals
(Eocene Thermal Maximum 2 – ETM2 – and H2). The later hyperthermals
occurred during warming that resulted in the Early Eocene Climatic Optimum
(EECO), the hottest sustained period of the Cenozoic. The PETM has been
comprehensively studied in marine and terrestrial settings, but the
terrestrial biotic effects of ETM2 and H2 are relatively unknown. Two carbon
isotope excursions (CIEs) have been described in the northern part of the
Bighorn Basin, WY, USA, and related to ETM2 and H2. An ~ 80 m thick
zone of stratigraphic section in the extraordinarily dense, well-studied
terrestrial mammal fossil record along the Fifteenmile Creek (FC) in the
south–central part of the basin spans the levels at which the CIEs occur in
the northern Bighorn Basin. High-resolution, multiparameter paleoecological
analysis of this part of the FC section reveals two episodes of significant
faunal change – faunal events B-1 and B-2 – characterized by significant
peaks in species diversity and turnover and changes in abundance and relative
body size. Faunal events B-1 and B-2 are hypothesized to be related to the
CIEs in the northern part of the basin and hence to the climatic and
environmental change of ETM2 and H2. In contrast with the PETM, change at
faunal events B-1 and B-2 is less extreme, is not driven by immigration and
involves a proliferation of body sizes, although abundance shifts tend to
favor smaller congeners. The response at faunal events B-1 and B-2 is
distinctive in its high proportion of species losses, potentially related to
heightened species vulnerability in response to changes already underway in
the lead-up to the EECO. Faunal response at faunal events B-1 and B-2 is also
distinctive in that it shows high proportions of beta richness, suggestive of
increased geographic dispersal related to transient increases in habitat
(floral) complexity and/or precipitation or seasonality of precipitation. |
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