Cretaceous–Paleogene extinction event

The Cretaceous-Paleogene (K-Pg) extinction event, also known as the K-T extinction, was a mass extinction that occurred approximately 66 million years ago[1][2]. This catastrophic event marked the end of the Cretaceous period and the Mesozoic era, wiping out about 75-80% of all plant and animal species on Earth, including most dinosaurs[1][2][4].

The primary cause of this extinction is widely attributed to the impact of a massive asteroid or comet, estimated to be 10-15 km wide, which struck the Earth near the Yucatán Peninsula in Mexico[2]. This impact created the 180 km-wide Chicxulub crater and triggered a series of devastating global effects[2][4]:

1. Massive tsunamis
2. Widespread wildfires
3. Global cooling due to dust and debris blocking sunlight
4. Acid rain
5. Disruption of photosynthesis

Evidence supporting the impact theory includes:

A thin layer of iridium-rich clay at the K-Pg boundary worldwide
The discovery of the Chicxulub crater
Presence of shocked quartz and tektites in boundary sediments

Some scientists also suggest that the Deccan Traps volcanism in India, which occurred around the same time, may have contributed to the extinction by releasing large amounts of greenhouse gases and causing climate changes[2][4].

The K-Pg extinction had profound effects on the evolution of life on Earth. It paved the way for the rise and diversification of mammals, birds, and flowering plants in the subsequent Paleogene period[2][4].

Citations:
[1] https://www.nationalgeographic.com/sc...
[2] https://encyclopedia.pub/entry/32558
[3] https://library.fiveable.me/key-terms...
[4] https://www.britannica.com/science/K-...
[5] https://ucmp.berkeley.edu/education/e...
[6] https://byjus.com/biology/kt-extinction/
[7] https://www.pnas.org/doi/full/10.1073...