Mesozoic Era

Definition

The Mesozoic Era is a geological time period that lasted from about 252 to 66 million years ago, marked by the dominance of dinosaurs and the appearance of mammals and birds. It is often referred to as the 'Age of Reptiles' due to the prevalence of dinosaurs as the dominant terrestrial vertebrates during this time, and is divided into three periods: the Triassic, Jurassic, and Cretaceous.

5 Must Know Facts For Your Next Test

1. The Mesozoic Era is divided into three distinct periods: Triassic, Jurassic, and Cretaceous, each showcasing different stages in dinosaur evolution.
2. This era saw significant geological changes, including the breakup of the supercontinent Pangaea, which affected climate and ocean circulation patterns.
3. Dinosaurs evolved into various forms and sizes during the Mesozoic Era, leading to a wide range of species adapted to different environments.
4. Mammals were small and mostly nocturnal during this era, but they began to diversify toward its end as dinosaurs dominated land ecosystems.
5. The Mesozoic Era ended with a mass extinction event around 66 million years ago, likely caused by an asteroid impact, leading to the demise of the dinosaurs.

Review Questions

• How did the breakup of Pangaea during the Mesozoic Era impact dinosaur evolution and distribution?
  • The breakup of Pangaea during the Mesozoic Era created new geographical barriers that isolated dinosaur populations, leading to divergent evolutionary paths. As continents drifted apart, different environmental conditions emerged, resulting in various adaptations among dinosaur species. This isolation facilitated speciation, allowing dinosaurs to evolve into diverse forms tailored to their specific habitats across different regions.
• Analyze the significance of the Cretaceous Period in relation to both dinosaur evolution and the emergence of flowering plants.
  • The Cretaceous Period was crucial for both dinosaur evolution and the rise of flowering plants. Dinosaurs reached their peak diversity during this time, with large herbivores adapting to new plant types. Meanwhile, flowering plants began to flourish, providing new food sources for herbivorous dinosaurs and altering ecosystems. This interplay between evolving species fostered complex ecological relationships that shaped the Mesozoic environment.
• Evaluate the impact of the mass extinction event at the end of the Mesozoic Era on Earth's biodiversity and subsequent evolutionary trends.
  • The mass extinction event at the end of the Mesozoic Era had a profound impact on Earth's biodiversity, resulting in the loss of approximately 75% of species, including all non-avian dinosaurs. This extinction created opportunities for mammals and other surviving groups to diversify and occupy ecological niches previously held by dinosaurs. The aftermath set the stage for significant evolutionary trends in the Cenozoic Era, where mammals became dominant terrestrial vertebrates and eventually gave rise to modern species.

Related terms

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

Cretaceous Period: The last period of the Mesozoic Era, lasting from about 145 to 66 million years ago, known for the dominance of dinosaurs and the first appearance of flowering plants.

Extinction Event: A significant reduction in biodiversity on Earth, with the most famous being the Cretaceous-Paleogene extinction event that led to the extinction of dinosaurs.