Rhynie Chert - Interactions

Interactions

The Rhynie chert, by preserving a snapshot of an ecosystem in situ in high fidelity, gives a unique opportunity to observe interactions between species and kingdoms. There is evidence of parasitic behaviour by fungi on algae Palaeonitella, provoking a hypertrophic response. Herbivory is also evident, judging by boring and piercing wounds in various states of repair, and the mouthparts of arthropods.

Coprolites - fossilised droppings - give a useful insight of what animals ate, even if the animals cannot be identified. Coprolites found in the Rhynie chert are typically between 0.5 and 3 mm in size, and contain a variety of contents. Analysis of coprolites allows the identification of different feeding modes, including detritovory and herbivory; some coprolites are so densely packed with spores that it is possible that these made up a substantial proportion of some organisms' diets.

Plants responded to fungal colonisation in different ways, depending on the fungus. The rhizoids of Nothia displayed three responses to fungal infestation: the hyphae of some (mutualistic) colonists were encased by plant cell walls; other (parasitic) fungi were met with typical host responses of increased rhizome cell size; while yet other fungi solicited an increase in thickness and pigmentation of cell walls. Once inside a plant cell, fungi produced spores, which are found in decaying plant cells; the cells may have decayed as a defence mechanism to prevent the fungi from spreading.

Fungal interactions are known to promote speciation in modern plants, and presumably also affected Devonian diversity by providing a selection pressure.

Mycorrhizae are also found in the Rhynie chert.