| Kronosaurus Temporal range: Lower Cretaceous | |
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| Harvard Museum of Natural History: restored with too many vertebrae | |
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| Genus: | Kronosaurus Longman, 1924 |


Kronosaurus was a large pliosaur, one of the largest. It is named after the leader of the Greek Titans, Kronos. It lived in the Lower Cretaceous.
Body-length estimates, based on the 1959 Harvard reconstruction, had put the total length of Kronosaurus at 12.8 meters (42 feet). However, a recent study compared fossil specimens of Kronosaurus to other pliosaurs. The Harvard reconstruction may have included too many vertebrae, exaggerating its length. Its true length was probably only 9–10.9 meters (30–36 feet).