Mosasaur, (family Mosasauridae), extinct group of aquatic lizards that attained a high degree of adaptation to the marine environment and were distributed worldwide during the Cretaceous Period (145.5 million to 66 million years ago).
The longest mosasaurs, based on a specimen of Mosasaurus hoffmanni, are estimated to have been 17 metres (about 56 feet) in length, but the most common forms were no larger than modern porpoises.
Mosasaur, (family Mosasauridae), extinct group of aquatic lizards that attained a high degree of adaptation to the marine environment and were distributed worldwide during the Cretaceous Period (145.5 million to 66 million years ago).
The longest mosasaurs, based on a specimen of Mosasaurus hoffmanni, are estimated to have been 17 metres (about 56 feet) in length, but the most common forms were no larger than modern porpoises.
