During which era did plesiosaurs, nothosaurs, and mosasaurs exist?

The correct answer is the Mesozoic Era, which is often referred to as the "Age of Reptiles." This time period, lasting from about 252 to 66 million years ago, saw the rise and dominance of various reptiles, including dinosaurs and marine reptiles like plesiosaurs, nothosaurs, and mosasaurs.

Plesiosaurs were known for their long necks and paddle-like limbs, while nothosaurs were somewhat similar but had a different body structure suited for their semi-aquatic lifestyle. Mosasaurs evolved later in the Mesozoic and were powerful marine predators, characterized by their elongated bodies and strong tails.

The other eras listed did not see the presence of these reptiles. The Paleozoic Era preceded the Mesozoic and was marked by the development of early life forms, including the first fish and amphibians, but it did not include the marine reptiles in question. The Cenozoic Era followed the Mesozoic and is characterized by the rise of mammals and birds, with reptiles being less dominant. Finally, the Jurassic Era is actually a period within the Mesozoic Era, so while it is a time frame when some of these reptiles existed, it does