Dinosaurs lived during the Mesozoic Era, which is often referred to as the "Age of Dinosaurs." The Mesozoic Era is divided into three periods:
Triassic Period (approximately 252 to 201 million years ago): Dinosaurs first appeared during the Triassic Period, evolving from earlier reptiles. The earliest dinosaurs were relatively small compared to some of the massive species that would later dominate the landscape.
Jurassic Period (approximately 201 to 145 million years ago): The Jurassic Period saw the diversification and dominance of dinosaurs. Some of the most iconic dinosaurs, such as the long-necked Brachiosaurus and the carnivorous Allosaurus, lived during this time.
Cretaceous Period (approximately 145 to 66 million years ago): The Cretaceous Period continued the dominance of dinosaurs, featuring a wide variety of species. It was during this period that some of the largest dinosaurs, including the Tyrannosaurus rex and the Triceratops, lived.
The extinction of the non-avian dinosaurs occurred at the end of the Cretaceous Period, approximately 66 million years ago. This mass extinction event, known as the Cretaceous-Paleogene (K-Pg) extinction event, marked the boundary between the Cretaceous and Paleogene periods. Several factors are believed to have contributed to the extinction of the dinosaurs:
Asteroid Impact: The leading hypothesis for the cause of the K-Pg extinction is the impact of a large asteroid or comet. The impact would have caused massive wildfires, a "nuclear winter" effect with dust and debris blocking sunlight, and a rapid and intense cooling of the Earth's climate.
Volcanic Activity: Intense volcanic activity in the Deccan Traps region (modern-day India) is considered a secondary contributing factor. The volcanic eruptions released large amounts of gases and particulates into the atmosphere, possibly exacerbating environmental stress.
Climate Change: The combination of the asteroid impact and volcanic activity likely led to significant and rapid climate changes. The cooling effect caused by debris in the atmosphere, along with the release of greenhouse gases, could have disrupted ecosystems and food chains.
The K-Pg extinction event had a profound impact on life on Earth, leading to the extinction of approximately 75% of Earth's species, including the non-avian dinosaurs. While some smaller animals, birds, and certain reptiles survived and evolved, the extinction of the dinosaurs allowed mammals and other groups to diversify and become dominant in the subsequent Cenozoic Era.
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