Serbet, Rudolph , Taylor, Thomas N. , Taylor, Edith L. .
Plant/animal interactions: Cretaceous leaf galls from southern Alberta, Canada.
Fossil galls are known from the Carboniferous to the recent. Although many have been described from compression/impression specimens, a small number have been recognized in permineralized fossils. Specimens from the Badlands of southern Alberta, offer new insights into the morphology and anatomy of several permineralized galls found on taxodiaceous conifers. From a sample of several thousand conifer leaves and leafy shoots, 10 leaf galls were isolated. Although the morphological similarity in shape and size suggests that these structures were produced by the same type of organism, anatomical sections provide evidence that perhaps these Cretaceous galls were produced by more then one kind of organism. Several galls were found on leafy shoots and occur on both the abaxial and adaxial surface of a leaf. Multiple galls on a single leaf have not been found. Individual galls can be up to 1.5 mm long; and approximately 1.0 mm high and wide. Typically the width of a gall equals the width of the leaf. Permineralized foliar galls provide the opportunity to examine modifications of the plant tissue caused by the gall inducer. In some galls there is a dark layer of cells surrounding the larval chamber. Exterior to this layer, the cells have thickened walls and are filled with opaque contents. In other galls the distribution of cell types is variable. These galls occur on leaves that are interpreted as being deciduous. This suggests that the galls remained active for at least one season. Galls provide a significant adaptation for those insects that induce them. Currently, three hypotheses are relevant when discussing the morphology of extant galls. These include galls functioning as a nutritive source, specialized micro-habitat, or as a protective structure against predation. Each of these functions will be discussed in relation to the morphological and anatomical features of these Cretaceous galls.
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1 - University of Kansas, Division of Paleobotany, Natural History Museum and Biodiversity Research Center, 1200 Sunnyside Ave., Lawrence, Kansas, 66045-7534, USA
2 - University of Kansas, Department of Ecology & Evolutionary Biology, Natural History Museum and Biodiversity Research Center, 1200 Sunnyside Avenue, Lawrence, Kansas, 66045-7534, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Lake Erie/Hilton
Date: Tuesday, July 10th, 2007
Time: 10:15 AM