Herbivory in Antarctic fossil forests and comparisons with modern analogues in Chile
During the Tertiary (-50 million years ago) forests were present in Antarctica, but fossil evidence of insect life in the forests is rare. Extensive fossil floras from Antarctica contain evidence of insect herbivory on the leaves; these provide indirect evidence of past insect life. Such preservatio...
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| Format: | Thesis |
| Language: | English |
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University of Leeds
2009
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| Online Access: | https://etheses.whiterose.ac.uk/11289/ https://etheses.whiterose.ac.uk/11289/1/507098.pdf |
| Summary: | During the Tertiary (-50 million years ago) forests were present in Antarctica, but fossil evidence of insect life in the forests is rare. Extensive fossil floras from Antarctica contain evidence of insect herbivory on the leaves; these provide indirect evidence of past insect life. Such preservation of the behaviour of insects (insect trace fossil) can be used to examine the diversity of insects that lived in the forests of Antarctica in the past. Palaeogene (65 Ma - 35 Ma) fossil floras from two localities on the Antarctic Peninsula (King George Island and Seymour Island) were examined for the presence of insect trace fossils. Fossil leaves were preserved as impressions and compressions within siltstones and sandstones and represent leaves that were preserved within a quiet lake environment (King George Island) or shallow marine setting (Seymour Island). The floras were dominated by leaf morphotypes that resemble modem Nothofagaceae (Southern beeches), but leaves similar to other Southern Hemisphere families were also present, including the Cunoniaceae, Proteaceae and Lauraceae. Over 2,000 fossil leaves were examined for traces of past insect activity. Over 150 fossil leaves (6.9%) contained evidence of feeding traces on the leaves (54 trace types from King George Island and 19 from Seymour Island). The trace fossils were grouped into four functional feeding types: general leaf chewing, skeleton feeding, leaf mines and leaf galls. General leaf chewing was the most common trace type at both localities and leaf mines the least common. The nearest living analogues of the Antarctic Palaeogene forests are the Valdivian and Magellanic forests of Chile and so insect activity in these forests was studied in order to understand past insect activity in Antarctica. The diversity of insect traces in the Chilean forests was investigated at six sites within National Parks, covering a latitudinal range between 37°S and 55°S. Insects associated with two deciduous species, Nothofagus pumilio and Nothofagus antarctica, were of ... |
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