<P class=MsoNormal dir=ltr style="MARGIN: 0in 0in 0pt" align=left><B><SPAN style="FONT-FAMILY: Arial">Creepia crawliensis - alive and well in the Trias</SPAN></B><FONT face="Times New Roman"> </FONT></P>
Creepia crawliensis - alive and well in the Trias
The Earth might have just suffered the greatest mass extinction in its history, but Triassic bugs just went right on munching... <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
Dwain Eldred writes: Plants and insects have been at war for more than 300 million years through good times and bad – slugging away even through major extinctions, like the end-Permian. But in the Triassic, both insects and plants diversified anew and although they remained at war, and some new battle lines were drawn, new treaties were renegotiated elsewhere as the relationship between insects and plants evolved.
Plant-insect interactions are not all predatory, of course. As anyone knows who has struggled through a thicket or two, plants have developed defences (physical and chemical). However in many cases they exploit insects for help in reproduction. These interactions first developed during the late Palaeozoic (Carboniferous and Permian in particular, 320-250 million years ago).
The end of the Permian represented a time when “Life nearly died”. Many plants and insects were wiped out. In the succeeding Triassic Period (250-200 million years ago) both plants and insects diversified with the evolution of many new groups. Research by Professor Andrew Scott (Royal Holloway, University of London) together with colleagues Drs. John and Heidi Anderson (National Botanic Garden, Pretoria, South Africa) is published this week in the Journal of the Geological Society. This seems to show that, by the end of the Triassic Period, diverse plant-insect interactions had re-evolved.
The material they studied came from the Molteno Formation (late Triassic, 200Ma) of South Africa. This formation has yielded more than 200 plant species from 100 plant assemblages at 69 localities (30,000 catalogued slabs) as well as more than 300 species of insect. Damage to leaves caused by insects (picture) is widespread. This damage includes feeding traces, leaf mines and probable leaf galls and indicates the exploitation by insects of plants as both food and shelter. Quantitative data on the insect damage obtained indicates that leaf damage between sites varies from 3 to 25% and within species from 1-50%.
Prof Scott says: “The Molteno data provide the earliest evidence of widespread plant-insect interaction in the Triassic record, following the Permo-Triassic ecosystem collapse and recovery. The abundance of plants and insects together at more than 30 localities means that evidence may be forthcoming on the co-evolution of plants and insects at this time.”
The lack of an abundant record of plant-insect interactions in the succeeding Jurassic Period (200-145 Ma) remains an enigma,