Even in the foundation stage (ages 3-5), children reveal an awareness of and enthusiasm for dinosaurs and fossils, so this research includes the entire primary age range. The authors sought to discover what ideas prevail as children develop and how their understanding progresses. Reviewing relevant educational research led them to define five overlapping areas of enquiry: (1) Variation exists within and between species; even sheep, tadpoles, broad beans and oak trees show variability. (2) Fossils are introduced at year 3 (age 7-8); by year 6 (age 10-11) children are expected to appreciate their relevance to evolution. Where's the continuity? (3) Selective breeding of farm and domestic animals offers access to ideas of inherited changes over generations. (4) Evolution as in Darwin's theory of natural selection can be accessed via his "tree of life" metaphor, as well as children's fiction, such as 'one smart fish" and "Charlie and the Kiwi." (5) Representing "deep time" is a challenge. The Earth's age is estimated at roughly 4.5 billion years, with hominid life for a miniscule fraction of that time. What sense do children make of various representations of time? What links with mathematics can be explored?