Time Period Category

Dinosaurs roamed the Earth during three primary geological periods: Triassic, Jurassic, and Cretaceous. Each era witnessed significant evolutionary advancements, diversification, and extinction events that shaped the course of dinosaur history. Understanding the distribution of dinosaur species across these time periods provides valuable insights into their adaptation, survival, and eventual demise.

Dinosaur Diversity by Geological Time Period

Key Geological Time Periods

Triassic period landscape with early dinosaurs

Triassic

The Triassic (252–201 million years ago) marks the dawn of dinosaurs, featuring early, smaller species and the emergence of archosaurs.

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Jurassic period with diverse dinosaur species

Jurassic

The Jurassic (201–145 million years ago) saw significant diversification, including the rise of large sauropods and iconic theropods.

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Cretaceous period with flourishing dinosaur fauna

Cretaceous

The Cretaceous (145–66 million years ago) was the final chapter for dinosaurs, featuring a peak in diversity before the mass extinction event.

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Curious about the entire Mesozoic cast? Dive into our List of 100 dinosaurs and discover surprising facts for each colossal creature!

Dinosaurs & Geological Time Periods

Dinosaurs first appeared during the **Triassic Period**, approximately 252 million years ago, following the Permian-Triassic extinction event. This era was characterized by arid climates and the breakup of the supercontinent Pangaea, leading to diverse habitats that facilitated the early evolution of dinosaurs.

The **Jurassic Period** (201–145 million years ago) witnessed a significant increase in dinosaur diversity and size. This era is renowned for the emergence of iconic species such as *Brachiosaurus* and *Allosaurus*. The warm and moist climates of the Jurassic promoted lush vegetation, supporting large herbivorous dinosaurs and their predators.

During the **Cretaceous Period** (145–66 million years ago), dinosaurs reached their peak in diversity and abundance. This period saw the rise of well-known species like *Tyrannosaurus rex*, *Triceratops*, and *Velociraptor*. Flowering plants began to dominate ecosystems, providing new food sources and influencing dinosaur evolution.

The end of the Cretaceous marked the **Cretaceous-Paleogene (K-Pg) extinction event**, approximately 66 million years ago, leading to the mass extinction of non-avian dinosaurs. This catastrophic event was likely caused by a combination of volcanic activity, climate change, and the impact of a large asteroid, which drastically altered global environments.

Paleontological studies continue to uncover new species and refine our knowledge of how dinosaurs adapted to changing Earth conditions over millions of years.