Duck-billed dinosaurs were successful and common herbivores from the upper Cretaceous period. The secret of their success perhaps lay with the duck-shaped bill that clipped vegetation and the many small teeth that ground it down. There were two types: some with a bony crest on their head for resonating sound and some without. Fossilised nest sites have shown that some species may have travelled to communal nesting grounds to lay eggs, as many bird species do today. Fossils from the many species are found all over modern-day Europe, Asia and North America, and show that some grew to around 12 metres.

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