Reconstructed setting· The columns of time
Mesozoic world
252 Ma → 66 Ma
Conifers, cycads and ferns for a canopy, large vertebrates beneath, and flowers only in the Cretaceous, the last of its three periods. The scene changes inside itself, and the date at which it does is the point.
What the evidence shows
The earlier Mesozoic flora was dominated by non-flowering plants, which is why the canopy carries needles and fronds and nothing in bloom. Flowers are drawn only from 145 million years, because the angiosperm transformation began in the Early Cretaceous and ran on through the Late Cretaceous: a backdrop with flowers throughout would misdate the largest change in the history of land vegetation. The large herbivores are there because vertebrate herbivory is what allowed the body sizes the era is known for.
Bounds and conventions
Three claims for 186 million years, which is thin. The flora is drawn from northern hemisphere evidence, and what the southern continents looked like through the same span is less well known and probably different.