Sharks survived the end-Cretaceous extinction, but they did not pass through it unchanged. Sharks, skates and rays together form the cartilaginous-fish group called elasmobranchs. A global study of more than 3,200 fossil occurrences and 675 species estimated that elasmobranch diversity fell by over 62% across the Cretaceous–Paleogene boundary, about 66 million years ago. The living survivors are the remainder of a much larger fauna that suffered severe losses.
What the fossil counts measure
The estimate counts species-level extinction and origination patterns across a defined interval. It is not a census of every individual fish killed by the impact, and it should not be read as a precise count of shark bodies. Fossil records are uneven: many sharks are known mainly from shed teeth, and the chance of finding a tooth depends on habitat, rock exposure, collecting and identification.
Even with those limits, the global analysis reveals a major ecological disruption. Elasmobranch diversity did not fully recover during the Paleocene. That makes “sharks survived” an incomplete summary: some lineages crossed the boundary, many disappeared, and communities took time to reorganise.
Survival varied across species and places
The study found higher survival among species with broad geographic ranges and among some taxa restricted to high-latitude settings. A wide range may have increased the chance that a lineage occupied areas less exposed to the harshest local effects or retained populations in more than one habitat. This is a statistical pattern, not proof that every widespread shark had a refuge or that latitude alone caused survival.
Sharks are not one ecological type. Cretaceous seas contained animals with different body sizes, feeding modes and habitats, as well as skates and rays adapted to life near the seabed. Those differences matter when testing which lineages persisted. A single story about “the shark body plan” cannot explain the fate of hundreds of species.
Food webs changed after the impact
The Chicxulub impact and its environmental aftermath disrupted marine food webs as well as terrestrial ecosystems. Studies of fossil shark teeth across the boundary find changes in the ecological roles represented among lamniform sharks. Such work can show a shift in tooth shape and inferred feeding ecology; it cannot reconstruct every predator-prey interaction or establish that all ocean habitats collapsed in the same way.
Teeth are especially useful because sharks continually replace them and fossil teeth can be abundant. But isolated teeth usually provide less taxonomic and anatomical information than associated skeletons. Researchers therefore combine tooth shape, stratigraphic position and assemblage composition, and compare those results with other marine evidence.
Survival is not the same as immunity
Some sharks persisted across the boundary and diversified later, but the extinction was a bottleneck for elasmobranch history. The surviving lineages did not simply resume the exact ecosystems that existed before the impact. Species losses altered communities, and new ecological structures emerged during recovery.
The longer history of sharks through mass extinctions includes several crises with different causes and outcomes. At the K–Pg boundary specifically, the most accurate conclusion is both dramatic and limited: elasmobranchs survived as a group, while a majority of species in the study’s fossil dataset did not.
Frequently asked questions
Did sharks survive the asteroid impact?
Some shark lineages survived the K–Pg extinction, but elasmobranch diversity fell sharply. Survival of the group does not mean that most species were unaffected.
How many shark and ray species went extinct?
A global study estimated a decline of more than 62% in elasmobranch species across the boundary, using fossil occurrences spanning the Late Cretaceous and Paleocene.
Which sharks were more likely to survive?
The analysis found higher survival among species with broad geographic ranges and some restricted to high-latitude settings. These are associations, not proof of one simple cause.
Why are fossil shark teeth important?
Sharks continually replace teeth, so isolated teeth are common and can track changes through rock layers. Their identification and ecological meaning still require careful comparison and context.