Mesozoic

Definition

The Mesozoic Era is a geological time frame that lasted from about 252 to 66 million years ago, often called the 'Age of Reptiles' due to the dominance of dinosaurs during this period. This era is divided into three major periods: the Triassic, Jurassic, and Cretaceous, each marked by significant evolutionary advancements and environmental changes that shaped the Earth's biosphere.

5 Must Know Facts For Your Next Test

1. The Mesozoic Era witnessed the breakup of the supercontinent Pangaea, leading to significant changes in climate and sea levels.
2. Dinosaurs became the dominant terrestrial vertebrates during the Mesozoic, evolving into various forms adapted to different environments.
3. This era saw the rise of early mammals and birds, which began to diversify in response to ecological opportunities.
4. The Mesozoic was marked by significant geological events such as volcanic activity and tectonic shifts that shaped the continents.
5. The end of the Mesozoic Era is famously associated with a mass extinction event caused by an asteroid impact, leading to the extinction of approximately 75% of Earth's species.

Review Questions

• What were some key evolutionary advancements during the Mesozoic Era, and how did they impact the biodiversity of the time?
  • During the Mesozoic Era, key evolutionary advancements included the rise and diversification of dinosaurs, as well as the emergence of early mammals and birds. Dinosaurs evolved into various forms, becoming dominant land animals while mammals remained small and less diverse. This era laid the groundwork for future evolutionary paths, as many ecological niches were filled by different types of reptiles and emerging mammals.
• Analyze how geological changes during the Mesozoic Era influenced climate patterns and ecosystems.
  • Geological changes during the Mesozoic Era, such as the breakup of Pangaea and tectonic activity, significantly influenced climate patterns and ecosystems. The formation of new ocean basins altered ocean currents, impacting global climates and leading to a variety of habitats. These changes allowed diverse plant life to flourish, which in turn supported a wide range of herbivorous dinosaurs and other species throughout this dynamic era.
• Evaluate the significance of the mass extinction event at the end of the Mesozoic Era and its consequences for life on Earth.
  • The mass extinction event at the end of the Mesozoic Era was significant because it led to the abrupt disappearance of about 75% of Earth's species, including all non-avian dinosaurs. This event reshaped ecosystems globally, allowing mammals to diversify and fill ecological niches left vacant by extinct species. The extinction set the stage for the rise of mammals in subsequent eras, dramatically altering life's trajectory on Earth and leading to the development of modern ecosystems.

Related terms

Triassic Period: The first period of the Mesozoic Era, occurring from about 252 to 201 million years ago, characterized by the emergence of dinosaurs and the first mammals.

Jurassic Period: The second period of the Mesozoic Era, spanning from about 201 to 145 million years ago, known for the further diversification of dinosaurs and the first appearance of birds.

Cretaceous Period: The last period of the Mesozoic Era, lasting from about 145 to 66 million years ago, marked by the dominance of flowering plants and culminating in a mass extinction event that wiped out many species, including dinosaurs.