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Which animals survived the Cretaceous-Paleogene extinction?

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Illustration showing various dinosaur species drawn to scale and grouped by geologic era: Late Cretaceous, Early Cretaceous, Jurassic, and Triassic. Dinosaurs range from large species like Brachiosaurus and Tyrannosaurus to smaller ones like Velociraptor and Compsognathus, with a human silhouette included for size comparison. Measurement bars at the bottom indicate 1 meter and 3 feet for scale reference. — dinosaur A selection of dinosaurs grouped by the geologic interval in which they lived.

The Cretaceous-Paleogene (K–Pg) extinction, which occurred approximately 66 million years ago, resulted in the loss of about 80 percent of all animal species. While non-avian dinosaurs and several other groups perished, many lineages survived to populate the Cenozoic Era.123

Surviving Animal Groups

Birds: As descendants of small theropod dinosaurs, birds survived the extinction event and underwent significant diversification.14
Reptiles: Several groups of reptiles were either unaffected or only slightly affected, including turtles, crocodilians, lizards, and snakes.15
Mammals: The effects of the extinction on mammals were relatively mild, allowing them to experience substantial evolutionary radiation in the ecological niches left vacant by the extinction of the dinosaurs.13
Amphibians: Like mammals, amphibians were relatively mildly affected by the event.15

While many marine invertebrates and planktonic organisms were decimated, a small percentage of planktonic genera remained, facilitating the recovery of marine ecosystems.12