The K-Pg (Cretaceous-Paleogene) extinction event, caused by a massive asteroid impact 66 million years ago, wiped out about 75% of all species on Earth, including all non-avian dinosaurs. However, many groups of animals did survive, often due to a combination of smaller size, generalized diets, and the ability to find shelter or live in aquatic environments. Here are the main categories of survivors:
Key Survivor Groups
- Mammals: All major groups of mammals survived, though they were generally small, nocturnal, and often burrowing. This allowed them to escape the immediate devastation and find food in the aftermath. Their ability to regulate body temperature and give live birth also played a role.
- Birds: Avian dinosaurs (birds) were the only lineage of dinosaurs to survive. Smaller body size, flight capabilities (allowing them to escape local devastation and find new food sources), and a more varied diet likely contributed to their survival.
- Reptiles: Many reptiles, including snakes, lizards, turtles, and crocodilians, survived. Their cold-blooded nature meant they could endure long periods without food, and many are semi-aquatic or burrowing, offering protection from the initial blast and subsequent environmental collapse.
- Amphibians: Frogs, salamanders, and caecilians largely survived. Their ability to live in water or burrow into mud provided refuge from the immediate heat and ash, and they could subsist on detritus or small invertebrates.
- Fish: Most fish species, especially those in deep-sea environments or freshwater systems, survived relatively well. The oceans provided a buffer against the atmospheric changes, and deep-sea ecosystems were less affected by surface events.
- Insects: Insects, with their incredible adaptability, small size, and diverse diets, were highly resilient and saw many lineages continue.
- Marine Invertebrates: Many marine invertebrates, particularly those living in deeper waters or able to withstand changes in ocean chemistry, survived. However, surface-dwelling plankton and ammonites (a type of shelled cephalopod) were severely impacted.
Pro tip: The common thread among most survivors was their ability to cope with a prolonged period of darkness and cold (impact winter), a scarcity of plant life, and a reliance on detritus or small, adaptable food sources rather than large, specialized prey or abundant vegetation.