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Endemism in Wyoming plant and insect herbivore communities during the early Eocene hothouse

Ellen D. Currano, Esther R. S. Pinheiro, Robert Buchwaldt, William C. Clyde and Ian M. Miller
Endemism in Wyoming plant and insect herbivore communities during the early Eocene hothouse
Paleobiology (August 2019) 45 (3): 421-439

Abstract

The warm, equable, and ice-free early Eocene Epoch permits investigation of ecosystem function and macro-ecological patterns during a very different climate regime than exists today. It also provides insight into what the future may entail, as anthropogenic CO (sub 2) release drives Earth toward a comparable hothouse condition. Studying plant-insect herbivore food webs during hothouse intervals is warranted, because these account for the majority of nonmicrobial terrestrial biodiversity. Here, we report new plant and insect herbivore damage census data from two floodplain sites in the Wind River Basin of central Wyoming, one in the Aycross Formation (50-48.25 Ma) at the basin edge (WRE) and the second in the Wind River Formation in the interior of the basin (WRI). The WRI site is in stratigraphic proximity to a volcanic ash that is newly dated to 52.416+ or -0.016/0.028/0.063 (2sigma ). We compare the Wind River Basin assemblages to published data from a 52.65 Ma floodplain flora in the neighboring Bighorn (BH) Basin and find that only 5.6% of plant taxa occur at all three sites and approximately 10% occur in both basins. The dissimilar floras support distinct suites of insect herbivores, as recorded by leaf damage. The relatively low-diversity BH flora has the highest diversity of insect damage, contrary to hypotheses that insect herbivore diversity tracks floral diversity. The distinctiveness of the WRE flora is likely due to its younger age and cooler reconstructed paleotemperature, but these factors are nearly identical for the WRI and BH floras. Site-specific microenvironmental factors that cannot be measured easily in deep time may account for these differences. Alternatively, the Owl Creek Mountains between the two basins may have provided a formidable barrier to the thermophilic organisms that inhabited the basin interiors, supporting Janzen's hypothesis that mountain passes appear higher in tropical environments.


ISSN: 0094-8373
EISSN: 1938-5331
Coden: PALBBM
Serial Title: Paleobiology
Serial Volume: 45
Serial Issue: 3
Title: Endemism in Wyoming plant and insect herbivore communities during the early Eocene hothouse
Affiliation: University of Wyoming, Department of Botany, Laramie, WY, United States
Pages: 421-439
Published: 201908
Text Language: English
Publisher: Paleontological Society, Lawrence, KS, United States
References: 82
Accession Number: 2020-032699
Categories: General paleontology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: NSF grants EAR-145031 and EAR-0643158
Illustration Description: illus. incl. 4 tables, geol. sketch map
N43°13'60" - N43°31'60", W109°37'60" - W108°05'60"
Secondary Affiliation: Boston University, USA, United StatesUniversity of New Hampshire, USA, United StatesDenver Museum of Nature and Science, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2020, American Geosciences Institute. Abstract, Copyright, The Paleontological Society. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 2020
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