The Cretaceous period, lasting from about 145 to 66 million years ago, was the final and longest period of the Mesozoic Era. It followed the Jurassic period and ended with the mass extinction event that wiped out most dinosaurs. During this time, the Earth’s landmasses began to resemble their modern positions as the supercontinent Pangaea continued to break apart, creating new oceans and shallow seas that reshaped habitats across the planet. The climate during most of the Cretaceous was warm and humid, with higher sea levels than today. Vast inland seas stretched across continents, dividing regions and allowing marine life to thrive. These conditions supported lush plant growth and provided diverse environments for animals to adapt to, from dense forests to coastal wetlands and open plains. Plant evolution advanced significantly in the Cretaceous with the rise of flowering plants, or angiosperms. These plants spread rapidly, outcompeting gymnosperms in many regions. Their presence transformed ecosystems, influencing the diets of herbivorous dinosaurs and contributing to the evolutionary success of pollinating insects like bees. Flowering plants helped reshape food chains and laid the foundation for modern terrestrial ecosystems. Dinosaurs reached their peak in variety during the Cretaceous, with famous species such as Tyrannosaurus rex, Triceratops, and Velociraptor appearing. Large herbivores and fierce predators dominated the land, while flying reptiles called pterosaurs ruled the skies alongside early birds. In the oceans, marine reptiles such as mosasaurs and plesiosaurs thrived, making the seas just as dangerous as the land. Mammals remained relatively small and less diverse than dinosaurs, but they continued to adapt throughout the Cretaceous. Many were nocturnal and preyed on insects, while some evolved to eat plants. Though overshadowed by dinosaurs at the time, these early mammals quietly diversified and prepared for their rise after the extinction event that would end the age of reptiles. The Cretaceous period ended about 66 million years ago with one of the most famous mass extinctions in history. Likely caused by a massive asteroid impact along with volcanic activity and climate change, this catastrophe wiped out the non-avian dinosaurs along with many marine reptiles and other species. Despite this devastation, the extinction ended the dominance of dinosaurs and allowed mammals to flourish, eventually leading to the age of mammals in the Cenozoic Era. (written by Perplexity)

The extinction of the dinosaurs at the end of the Cretaceous period, around 66 million years ago, was one of the most dramatic events in Earth’s history. Known as the Cretaceous-Paleogene (K-Pg) extinction event, it marked the end of the Mesozoic Era and the disappearance of nearly three-quarters of all species on Earth. Dinosaurs, which had dominated the land for more than 160 million years, suddenly vanished along with many marine reptiles, flying pterosaurs, and a wide range of plants and smaller organisms. One of the leading causes of this extinction is believed to have been a massive asteroid impact. Evidence for this comes from the discovery of a large crater near the Yucatán Peninsula in Mexico, called the Chicxulub crater. The impact would have released enormous energy, causing wildfires, earthquakes, and tsunamis across the globe. It also ejected vast amounts of debris into the atmosphere, blocking sunlight for months and leading to a sharp drop in global temperatures. In addition to the asteroid impact, intense volcanic activity in present-day India played a major role. The eruptions that created the Deccan Traps released large amounts of carbon dioxide and sulfur dioxide, contributing to long-term climate change. This would have caused acid rain, ocean acidification, and shifts in global temperatures that put stress on ecosystems even before the asteroid struck. The aftermath of these events drastically changed food chains worldwide. With sunlight blocked and global plant life declining, herbivorous dinosaurs struggled to find enough food, which in turn affected the carnivores that relied on them. Plankton and other small ocean organisms also collapsed, disrupting marine ecosystems and leading to the extinction of large sea reptiles such as mosasaurs and plesiosaurs. Interestingly, not all dinosaurs went extinct. Birds, which are considered a group of small feathered theropod dinosaurs, survived the catastrophe. Their smaller size, varied diets, and ability to fly may have given them survival advantages during this difficult time. Alongside birds, mammals, crocodiles, turtles, and certain plant species were also able to endure, eventually adapting and expanding during the new Cenozoic Era. The extinction of dinosaurs at the end of the Cretaceous opened the door to new life forms dominating the planet. With dinosaurs no longer ruling the land, mammals began to evolve into larger and more diverse species. This shift set the stage for the eventual rise of humans millions of years later. (written by Perplexity)