Paper No. 10
Presentation Time: 10:45 AM
Patterns of Terrestrial Herbivory from the Permian to the TRIASSIC In Euramerica and Gondwana
The end-Permian extinction had a profound effect on local community structure as well as constituent plant-insect associations. Preliminary data indicates distinctive herbivore syndromes typifying Permian versus Late Triassic styles of plant damage. Permian Euramerican sites from Texas (Taint, Coprolite Bone Bed) exhibit a tenfold range in the amount of herbivory based on surface-area quantification, also noted by visual estimation for Permian Karoo Basin sites from South Africa (Hammanskraal, Colenso, Wapadsburg Old). All Permian sites are dominated by exophytic (external) modes of feeding particularly external foliage feeding. There are rare examples of endophytic (internal) feeding, such as galling and seed predation, and evidence is lacking for leaf mining. In Gondwana, an abundance of oviposition occurs on glossopterid leaves that is absent in Euramerica. Collectively, Permian insect damage diversity across all sites is modest, representing 20 damage types (DTs) of external foliage feeding, 1 DT for piercing-and-sucking, 4 DTs for oviposition, 6 DTs for galling, and 2 DTs for seed predation, for a total of 30 known DTs.
Triassic sites have similar surface-area damage levels, based on visual estimation of Karoo Basin sites in South Africa (Umkomaas 111, Aasvoëlberg 411, Kannaskop 111). By contrast, a pronounced rise in damage diversity typifies Late Triassic sites when compared to the Permian. The 106 Molteno Formation sites have 78 total DTs, of which 30 are external foliage feeding, 8 piercing-and-sucking, 10 oviposition, 7 mining, 15 galling, 4 seed predation, 2 boring, and 2 unknown. There was a dramatic expansion of endophytic use of plant tissues by gallers, leaf miners, seed predators and ovipositing insects. The modest antecedents to this heightened damage can be found in Middle Triassic floras (Burgersdorp, Grés à Voltzia, Lower Keuper) which bear a diminutive spectrum of DTs when compared to those of the Late Triassic within the same basin.