Mosasaur
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Mosasaurs are an extinct group of large aquatic reptiles within the family Mosasauridae that lived during the Late Cretaceous. Their first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764. They belong to the order Squamata, which includes lizards and snakes.
Fossil shell of ammonite Placenticeras whitfieldi showing punctures caused by the bite of a mosasaur, Peabody Museum of Natural History, Yale
A tooth from a mosasaur
Scales of Tylosaurus proriger (KUVP-1075)
Fibrous tissues and microstructures recovered from Prognathodon specimen IRSNB 1624
Cretaceous
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The Cretaceous is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin creta, "chalk", which is abundant in the latter half of the period. It is usually abbreviated K, for its German translation Kreide.
The impact of a meteorite or comet is today widely accepted as the main reason for the Cretaceous–Paleogene extinction event.
Drawing of fossil jaws of Mosasaurus hoffmanni, from the Maastrichtian of Dutch Limburg, by Dutch geologist Pieter Harting (1866)
Scipionyx, a theropod dinosaur from the Early Cretaceous of Italy
Facsimile of a fossil of Archaefructus from the Yixian Formation, China