Mesozoic marine reptiles

Article By:

O’Keefe, F. Robin Department of Biology, Marshall University, Huntington, West Virginia.

Last reviewed:2008

DOI:https://doi.org/10.1036/1097-8542.YB081320

The Mesozoic Era (an interval from 245 to 65 million years ago), commonly known as the Age of Dinosaurs, was a time in Earth's history when reptiles were the dominant large animals in most ecosystems. The roles played today by mammals such as lions, antelope, and elephants were filled in the Mesozoic by different types of dinosaurs, familiar, large reptiles closely related to crocodiles and birds. However, other groups of large reptiles also lived during this time, and most are less familiar. The Mesozoic oceans played host to a myriad of large reptiles, including ichthyosaurs, plesiosaurs, nothosaurs, placodonts, and mosasaurs. Each of these groups of reptiles contained many species, some among the largest creatures ever to live in the oceans, and none of them were dinosaurs. These animals may be thought of as analogous to the whales, seals, and otters of today. This article will discuss each of these groups in turn. The relationships of the various groups, and of the groups to mammals, are depicted in Fig. 1.

The content above is only an excerpt.