Ocean life in the time of dinosaurs / Океаническая жизнь времен динозавров

Fossil. The mere word kicks most people’s imagination into high gear. It mostly evokes dinosaurs, of course—the stars of the Mesozoic era. And yet, because those famous reptiles are already the focus of many other books, in this book we will discuss different but no less fascinating kinds of animals: the ones that many people refer to incorrectly as “marine dinosaurs.”To explain how these reptiles—which were contemporaries of dinosaurs and could be just as imposing—were completely different from their terrestrial relatives, we will take you on a voyage that begins roughly 300 million years ago (abbreviated as 300 Ma), on an Earth considerably different from the one you know today. It was around that time that reptiles started to make significant returns to the aquatic life of their (and your) ancestors.

During the Mesozoic (252–66 Ma), considered the golden age of reptiles, reptiles predominated in all ecosystems and occupied extremely varied ecological niches—on land, following the example of the dinosaurs; in the air, with the pterosaurs; and in the oceans. Yet, about a hundred million years after fourlegged vertebrates (tetrapods) first left the water and colonized the land, which they did in the Late Devonian (380–360 Ma), a certain number of lineages followed the opposite path. That is to say that, long before the appearance of the first dinosaurs, several groups of reptiles, all of which originated from terrestrial ancestors, secondarily and independently adapted to the aquatic environment. The kinds of pressures from natural selection that led to this (re)colonization of the aquatic environment are still being researched. <...>