The plant-eating dinosaurs over the time they existed should have developed a system for dealing with a readily available plant source,that was toxic i.e. the cycads.
Dear Paul,
some fascinating articles as follows:
https://www.researchgate.net/publication/24001734_Diversity_patterns_amongst_herbivorous_dinosaurs_and_plants_during_the_Cretaceous_Implications_for_hypotheses_of_dinosaurangiosperm_co-evolution
http://onlinelibrary.wiley.com/doi/10.1111/j.1469-185X.2008.00065.x/abstract
https://www.researchgate.net/publication/266138574_Coevolution_of_cycads_and_dinosaurs
I hope this is useful, all best
Danilo
Article Diversity patterns amongst herbivorous dinosaurs and plants ...
Article Coevolution of cycads and dinosaurs
Fascinating question! I seem to remember, dredging memory, that an eminent entomologists from the University of Bristol (whose name I am unable to recall) suggested that angiosperm flowers were warning colours to herbivorous ceratopsian reptiles. Folowing from that thread comes the roles of the flamboyant reproductive structures of some Bennititales being more than for pollen movement.
Modern (and ancient cycads?) contain various secondary compounds, poisonous fruits (for some possible consumers), lots of phenols, and are immensely tough and fibrous. Such features would deter many kinds of herbivores. Those that could ingest and digest cycad vegetation would presumably have had a suite of character to allow for that, including detoxification systems (enzymes and gut symbionts), complex guts with caeca (as in many modern birds), continually growing teeth, and powerful jaws.
Thank you for the question.
Peter
Peter Kevan
Great debate! Two very naïve questions. Is there evidence that all cycads from the Mesozoic were toxic? Is it possible that the toxic ones remained longer on Earth and were easily fossilized?