The K‑T (K‑Pg) mass extinction erased roughly 75% of species, including iconic dinosaurs, marine reptiles, and countless smaller animals, reshaping Earth’s ecosystems and setting the stage for mammalian dominance.
Quick Answer
The K‑T mass extinction, now called the Cretaceous‑Paleogene (K‑Pg) event, occurred about 66 million years ago and eliminated three‑quarters of global species, ranging from non‑avian dinosaurs to marine mosasaurs and many insects and amphibians. The leading scientific explanation combines a 10‑km asteroid impact at the Yucatán Peninsula with massive Deccan Traps volcanism, both of which triggered rapid climate cooling, ocean acidification, and food‑web collapse. While the exact contribution of each factor remains debated, the consensus is that these rapid, global disturbances caused the abrupt loss of animal groups, opening ecological niches that later allowed mammals to diversify. Uncertainty remains around the timing of volcanic pulses relative to the impact and the degree of regional variation in extinction severity.
Frequently Asked Questions
What does the term K‑T (K‑Pg) mass extinction refer to?
The K‑T, now more accurately called the Cretaceous‑Paleogene (K‑Pg) extinction, marks the abrupt loss of about 75 % of Earth’s species around 66 million years ago, including all non‑avian dinosaurs and many marine and terrestrial animals.
What were the two main drivers behind the K‑Pg extinction?
Scientists cite a 10‑km asteroid impact that formed the Chicxulub crater and intense volcanism of the Deccan Traps as the primary drivers, both of which caused rapid climate change, darkness, and ecosystem collapse.
Which animal groups survived the K‑Pg event?
Survivors included small mammals, some bird lineages (the only surviving dinosaurs), crocodilians, turtles, and many invertebrates such as certain insects and mollusks that could tolerate the harsh post‑impact conditions.
How do researchers know the extinction happened 66 million years ago?
Radiometric dating of the iridium‑rich boundary clay, ash layers, and the Chicxulub impact melt rocks consistently yield ages around 66 million years, providing a precise timestamp for the event.
What modern lessons can we learn from the K‑Pg extinction?
The event shows how rapid, global disturbances can erase biodiversity and restructure ecosystems, underscoring the importance of preventing today’s accelerating extinction crisis caused by habitat loss, climate change, and pollution.
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