How long ago did flowering seed-plants become the dominant tree types?

Flowering seed-plants, or angiOSperms, became the dominant tree types around 100 to 120 million years ago during the Cretaceous period. They gradually replaced gymnosperms, such as conifers, as the primary tree types in many ecosystems. By the end of the Cretaceous, angiOSperms had established a significant ecological presence, leading to their dominance in modern forests.