End-Cretaceous Extinction

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The End-Cretaceous Extinction, also known as the Cretaceous-Paleogene (K-Pg) extinction, occurred approximately 66 million years ago. This event is famous for marking the end of the dinosaurs, except for their avian descendants. The extinction was not limited to dinosaurs; it affected a wide range of species, including marine reptiles, pterosaurs, and many invertebrates like ammonites and certain bivalves. The impact of a large asteroid, which created the Chicxulub crater in Mexico, is widely accepted as a primary cause of this extinction. The asteroid's collision ejected massive amounts of debris into the atmosphere, leading to a prolonged period of cold and darkness that disrupted photosynthesis and food chains. The asteroid impact was likely exacerbated by other factors, such as large-scale volcanic activity in India's Deccan Traps. These volcanic eruptions released gases that could have further altered the climate. Despite these factors, the asteroid impact remains the most significant cause of the extinction. The event marked the end of the Mesozoic Era and the beginning of the Cenozoic Era, allowing mammals and other surviving groups to flourish and diversify. The K-Pg boundary, a thin layer of sediment rich in iridium, serves as a geological marker for this event. The aftermath of the extinction paved the way for the evolution of modern ecosystems and life forms.