The recovery of extinct species

Since genetic engineering began, in the last quarter of the 20th century, the idea arose of the possible recovery of extinct species. In 1990, Michael Crichton published his famous novel Jurassic Park, which is based on the practical realization of this idea to reconstruct various species of dinosaurs and set up with them a very special zoo. I talked about this novel in this previous post, and in this one.

Mesozoic marine reptiles

Jules Verne

In 1867, Jules Verne published his famous novel Journey to the Center of the Earth, whose protagonists discover an underground ocean at great depth, which they baptize as the Liddenbrock Sea, and witness the fight to the death of two great marine animals: a plesiosaur and an ichthyosaur, supposed descendants of ancestors that sank with the Liddenbrock Sea a hundred million years before and survived down there, protected by the Earth's crust, while their surface congeners became extinct as a result of the impact of the meteorite or comet that put an end to most dinosaurs, although that was not known in Verne’s time. But what were those plesiosaurs and those ichthyosaurs that populated the seas during the Mesozoic, formerly called the Secondary Era?

At the dawn of the age of dinosaurs, the oceans of the Earth were joined in a single sea, Panthalassa, which surrounded the supercontinent Pangaea. In that global ocean, at the beginning of the Triassic period, ichthyosaurs appeared. Since the Jurassic, and during the rest of the Mesozoic, Pangaea gradually fragmented, giving rise to new seas.

The extinction of the dinosaurs

Since their discovery, at the beginning of the 19th century, dinosaurs have always awakened human imagination. The past existence of such large animals, which seemed to have left no trace in the current fauna, is quite suggestive. In the multitudinous field of science, dinosaurs have always occupied an extremely attractive place. Dinosaurs have appeal.

On the other hand, the mystery of the disappearance of dinosaurs was soon posited. What could have caused their extinction? In the next century and a half, various possible causes were proposed, such as the following:

• It was said, for example, that primitive mammals could have caused the extinction of dinosaurs by eating their eggs. The trouble is, both groups of animals lived together for a hundred million years without any problem. In fact, mammals were cornered by their giant neighbors and could not develop and spread until they disappeared.
• It was also said that the apparition of flowering plants (Angiosperms) during the Cretaceous period, the last when dinosaurs lived, could have caused their extinction by a change in their diet. The trouble is, the Cretaceous period was very long, and flowering plants appeared thirty million years before the extinction of the dinosaurs. If they could put up with that diet for so long, why should it suddenly be fatal for them?
• Another reason adduced was a change of climate. During the Mesozoic Era (the age of the dinosaurs) the Earth's climate was quite warm. Then, in the Tertiary period, it was colder. The bad news is that climate changes are usually gradual, while the disappearance of dinosaurs does seem to have been quite fast. Therefore it was proposed that the cause of the extinction could have been a sudden catastrophe that would have caused a sudden climate change.