What were the three periods that divided the Mesozoic era?

The Mesozoic era is divided into the Triassic, Jurassic, and Cretaceous periods.
The Mesozoic era is divided into the following periods from oldest to youngest:
Triassic
Jurassic
Cretaceous
The Triassic period was the first and oldest period of the Mesozoic era which occurred approximately 251 to 199.6 million years ago. It was known for the emerging diversity of land animals outside the ocean. During this time, spread in the Tethys Sea, which caused Pangaea to separate into two continents known as Laurasia and Gondwana.
The Jurassic period occurred approximately 199.6 to 145.5 million years ago. At the start of the period, Laurasia became North America and Eurasia. Meanwhile, the western portion of Gondwana became South America and Africa, while the eastern portion became Antarctica, Madagascar, India, and Australia. By this time, the continents were separated by oceans with higher sea levels, creating a more tropical climate. This led to the emergence of many new species, especially the famously known dinosaurs.
The Cretaceous period was the last and youngest period of the Mesozoic Period which occurred approximately 145.5 to 65.5 million years ago. Plants and animals flourished throughout the globe at the time until a celestial object killed off the dinosaurs. An asteroid or comet was theorized to have created the Chicxulub crater underneath the Yucatán Peninsula in Mexico. As a result, more than half of all the species on Earth had died off.