The Mesozoic Era began 252 million years ago with the largest mass extinction in Earth’s history and ended 66 million years ago with the asteroid that killed off the dinosaurs. This lesson will cover the important events that occurred during the Mesozoic Era.
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. The cause of the extinction is not fully understood, but eventually it led to dinosaurs dominating the planet for 135 million years.
The rise of the dinosaurs began at the end of the Triassic Period. This gave rise to a two-legged omnivore roughly three feet long named Eoraptor. Scientists believe the Eoraptor thrived and evolved into the many species of dinosaurs that would dominate the planet during the Jurassic period.Dinosaurs dominated the planet for 135 million years during the Jurassic and Cretaceous Periods.
The age of the dinosaurs saw over 1,000 different species covering land and the ocean. One of the largest dinosaurs discovered to date was the Argentinosaurus, weighing as much as 200,000 pounds.
Continents and Climate of the Mesozoic Era
The Mesozoic Era began with today’s continents combined into one large land mass known as Pangea, which was surrounded by a single global ocean called Panthalassa.During the Jurassic Period, a rift between modern day Africa and South America began to split Pangea apart. This began the formation of the continents as we know them today. Even today, this same rift continues to spread the coasts of the Atlantic further apart.It is believed that the Mesozoic Era was a dry climate for most of the time due to the abundance of evaporates, which is a type of mineral that only forms in dry climates.
Fossils from the Mesozoic also indicate a warm and dry climate.One such example is the finding of fern fossils in high latitudes (areas that are generally cold now) from this era that appear to have existed in a warm climate. Ferns today cannot survive freezing temperatures, which leaves two possibilities: either the high altitudes were generally warmer for the ferns to survive, or ferns from the Mesozoic were able to withstand cold temperatures.
End of the Mesozoic Era
The Mesozoic Era came to an abrupt and violent end during the Cretaceous Period. Sixty-five million years ago, an asteroid roughly six miles across slammed into the Yucatan Peninsula in Mexico.
The impact released a devastating shockwave and tsunami that caused massive devastation worldwide. The impact also released dust and debris from the ground into the atmosphere, blocking out the Sun and causing a winter that possibly lasted years. Roughly 75% of all life, most notably dinosaurs, went extinct from this impact. Left to thrive were small birds and mammals that were able to adapt to the harsh new environment.
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. Scientists believe the Eoraptor thrived and evolved into the many species of dinosaurs that would dominate the planet during the Jurassic Period. The Triassic Period started with a large single continent called Pangea, but by the Cretaceous Period, Pangea had begun to split apart. The split of Pangea began the formation of the continents as we recognize them today.
Lesson at a Glance
The Eoraptor was a dinosaur that thrived and evolved into many species of dinosaurs during the Mesozoic Era. The Mesozoic Era was when there was a warm climate that dinosaurs thrived in for 135 million years. It was also during this period that Pangea would begin to split apart, starting the formation of the continents we know them as today.
Your study efforts could result in your ability to:
- List and give details about the three geologic periods of the Mesozoic Era
- Make observations about the formation of the continents as well as the climate of the Mesozoic Era
- Convey the reason that the Mesozoic Era ended