INSECT FOLIVORY IN AN ANGIOSPERM-DOMINATED FLORA FROM THE MID-CRETACEOUS OF UTAH, USA

摘要

The Soap Wash flora contains 152 angiosperm leaf fossils from the Albian-Cenomanian boundary of central Utah. The flora exhibits many well-preserved examples of insect folivory for which the extent and type of damage on each leaf was recorded. Fewer than half of the specimens in the collection exhibit insect damage and most of the leaf damage affects less than five percent of the leaf area. Damage was distributed unevenly across the 18 leaf morphotypes described in the flora. Nineteen damage types were recognized. Most of the damage was of a generalized type, dominated by indiscriminate removal of leaf tissues (whole leaf feeding). We observed no correlation between leaf mass per area (MA) and the degree of damage by herbivores, which contrasts with Cenozoic and modern patterns. The low rate, modest area, and low diversity of damage type is similar to patterns reported through the Late Cretaceous and is consistent with a plateau in insect folivore diversity that persisted through the end of the Mesozoic. The preponderance of generalized damage types dominated by whole leaf feeding may reflect (1) the early stage in angiosperm radiation represented by this flora, and (2) the associated lag in folivore diversification and specialization.