Precambrian
In the Mesozoic Era, during the cretaceous period
There were actually three types of plants that evolved in the Mesozoic. Cycads and ginkgos evolved around the late Triassic and early Jurassic. The firsts flowering plants appear in the fossil record during the early Cretaceous period of the Mesozoic era.
I know that the angiosperms were most dominant during the cretaceous period but im not too sure about the dinosaurs dominant era. I would assume they were both dominant in the same era but I am not 100% sure.Read more: http://wiki.answers.com/Dinosaurs_and_angiosperms_were_dominant_lineages_during_with_geologic_era#ixzz1G5bqBpQR
Cycads and ginkgoes were important plants to the world's terrestrial ecosystems during the Mesozoic era, which lasted from around 252 million years ago to 66 million years ago. They were dominant plant groups during this time and played a significant role in the ecosystems of that period.
Events during the Mesozoic include the increasing dominance of dinosaurs. The Mesozoic is marked by the appearance of flowering plants.
Flowering plants first appeared around 140 million years ago during the Cretaceous period. They rapidly diversified and became the dominant group of plants, replacing many of the existing groups at the time.
Pines and Cypresses
Precambrian
Okay first of all, humans did NOT evolve from monkeys or anything like that. So there were NO plants that became dominant as humans evolved. Evolving is for dummies!! :0)
During the Mesozoic Era, flowering plants (angiosperms) were not yet common, as they emerged later in the era, around the Late Cretaceous. Additionally, many modern plant families, such as those found in tropical rainforests, were also absent or not fully developed during this time. Instead, the Mesozoic landscape was dominated by ferns, cycads, ginkgoes, and conifers.
In the Paleozoic period, animals such as trilobites, brachiopods, ammonites, and early vertebrates flourished. Plants included ferns, horsetails, and early seed plants. During the Mesozoic period, dinosaurs, marine reptiles like ichthyosaurs and plesiosaurs, as well as early mammals and birds were prevalent. Plants such as conifers, cycads, and ginkgoes thrived during this time.
According to the related link, the climate during the Mesozoic was warm; so warm that there were no ice caps at all, even at the poles. Plants grew in the warmth and moisture.