Abstract
Evidence for invertebrate feeding on glossopterid gymnosperms is documented from Middle Permian silicified peats of the Prince Charles Mountains, Antarctica, in the form of coprolites occurring both free in the peat matrix and clustered within excavations in roots, aerial wood and leaves. Observations of coprolites in thin-sections of the peats and from scanning electron microscopy of examples extracted via bulk maceration reveal nine morphotypes distinguished by size, shape, surface texture and contents. These include coprolites with coarse plant debris, spirally ornamented coprolites, coprolites containing spore/pollen remains and fern sporangia, coprolites within Glossopteris leaves, an ellipsoidal morphotype within a fern sporangium, large isolated coprolites between matted leaves, clustered forms filling galleries inside Vertebraria roots and Australoxylon wood, forms with coarse indeterminate constituents and others with fungal contents. Other faunal evidence is limited to indeterminate arthropod exoskeleton fragments. Collectively, the coprolites within the permineralised peat from the Prince Charles Mountains document the presence of diverse feeding behaviours including stem feeding, sporangial feeding, palynivory, root feeding and mycophagy. The first evidence of invertebrate feeding traces in Vertebraria (glossopterid) roots is identified. These findings indicate that herbivory by invertebrates in the high-latitude Permian forest-mire ecosystems of Antarctica was more intense and diverse than previous studies have reported, and affected all parts of the Glossopteris plant, together with components of associated herbaceous taxa.
Highlights
The first terrestrial arthropods of the early to mid-Palaeozoic appear to have been mostly predators and detritivores based on mouthpart morphology and early coprolite evidence (Jeram et al, 1990; Labandeira and Beall, 1990) recent evidence suggests the targeting of nutritious sporangial contents by the late Silurian (Edwards et al, 1995; Hagström and Mehlqvist, 2012)
We have found no arthropod body fossils associated with this Prince Charles Mountains (PCMs) coprolite morphotype
We diagrammatically reconstruct the key interactions between the glossopterid plant and invertebrates based on examples from Antarctica and Australia (Fig. 1)
Summary
The first terrestrial arthropods of the early to mid-Palaeozoic appear to have been mostly predators and detritivores based on mouthpart morphology and early coprolite evidence (Jeram et al, 1990; Labandeira and Beall, 1990) recent evidence suggests the targeting of nutritious sporangial contents by the late Silurian (Edwards et al, 1995; Hagström and Mehlqvist, 2012) It is not until the accumulation of silicified wetland deposits of the Rhynie Chert in the Early Devonian that a more detailed picture of early invertebrate–plant interactions can be gathered (Labandeira, 2007) based upon multiple forms of coprolites, plant tissue damage and animal body fossils.
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