Following the Paleozoic, the Mesozoic extended roughly 186 million years, from 252.17 to 66 million years ago when the Cenozoic Era began. This time frame is separated into three geologic periods.
https://en.wikipedia.org/wiki/Mesozoic
The Cretaceous is the longest era in the Mesozoic, but has only two periods: the Early Cretaceous, and the Late Cretaceous. Tylosaurus (a mosasaur) hunting Xiphactinus. The Early Cretaceous spans from 145 million to 100 million years ago.
https://en.wikipedia.org/wiki/Mesozoic
The Mesozoic era lasted nearly 200 million years, starting and ending with mass extinctions. This era consisted of the Triassic, Jurassic, and Cretaceous periods. The Mesozoic is thought to have had a warm climate that dinosaurs thrived in for 135 million years.
http://study.com/academy/lesson/the-mesozoic-era-facts-events-timeline.html
Sea levels began to rise during the Jurassic, which was probably caused by an increase in seafloor spreading. The formation of new crust beneath the surface displaced ocean waters by as much as 200 m (656 ft) more than today, which flooded coastal areas.
https://en.wikipedia.org/wiki/Mesozoic
Global paleogeographic reconstruction of the Earth in the late Cretaceous period 90 million years ago. (Courtesy Dr. Ron Blakey). The Mesozoic Era is the age of the dinosaurs and lasted almost 180 million years from approximately 250 to 65 million years ago. This era includes 3 well known periods called the Triassic, Jurassic, and Cretaceous periods. A mass-extinction marked the beginning and end of the Mesozoic Era. The event that caused the transition from the Paleozoic era to the Mesozoic era was the greatest extinction this earth has seen. This extinction wiped out about 95% of all marine life and 70% of land-life.
http://scienceviews.com/dinosaurs/mesozoic.html
The Mesozoic was also a time of great change in the terrestrial vegetation. The early Mesozoic was dominated by ferns, cycads, ginkgophytes, bennettitaleans, and other unusual plants. Modern gymnosperms, such as conifers, first appeared in their current recognizable forms in the early Triassic.
http://www.ucmp.berkeley.edu/mesozoic/mesozoic.php
The Mesozoic Era. The Mesozoic Era is divided into three time periods: the Triassic (251-199.6 million years ago), the Jurassic (199.6-145.5 million years ago), and the Cretaceous (145.5-65.5 million years ago).*.
http://www.ucmp.berkeley.edu/mesozoic/mesozoic.php
The Mesozoic was a time of significant tectonic, climate and evolutionary activity. The era witnessed the gradual rifting of the supercontinent Pangaea into separate landmasses that would eventually move into their current positions.
https://en.wikipedia.org/wiki/Mesozoic
The Jurassic ranges from 200 million years to 145 million years ago and features 3 major epochs: The Early Jurassic, the Middle Jurassic, and the Late Jurassic. The Early Jurassic spans from 200 million years to 175 million years ago.
https://en.wikipedia.org/wiki/Mesozoic
THE MESOZOIC ERA. The Mesozoic era is commonly subdivided into three geologic periods: Triassic (252 to 201.3 million years ago). Jurassic (201.3 to 145 million years ago). Cretaceous (145 to 66 million years ago). The Mesozoic era begins in the wake of the largest extinction in Earth's history. This extinction took place 252 million years ago and resulted in 96% of marine life and 70% of terrestrial life dying out.
http://study.com/academy/lesson/the-mesozoic-era-facts-events-timeline.html
when did the mesozoic era end
The Mesozoic Era ended 180 million years from approximately 250 to 65 million years ago. The Mesozoic Era ended 65 to 250 million years ago.