Life Before the Flood: Hot and Swampy

Early 19th-century paleontologists postulated a world for the dinosaurs to inhabit no less strange than the creatures themselves. Plant fossils hinted that no flowers bloomed to add color or fragrance to the Age of Reptiles. Instead, conifers spread their feathery needles over gigantic ferns, cycads, and horsetails. These thrived in a climate even hotter than today's tropics. The air, naturalists thought, was denser and higher in carbon dioxide, shrouding the landscape in stifling mist.

Many of the first fossils recognized in the 18th century to be the remains of ancient animals, rather than merely odd rocks, were aquatic, such as the great spiraling ammonites. And by the time the first dinosaurs were understood as such in the 1820s, seagoing reptiles such as Ichthyosaurus and Plesiosaurus had been known for over a decade. So the Mesozoic world was naturally presumed to be covered in sea and swamp and dotted by islands.

The comparative anatomist Richard Owen saw this as the perfect dinosaur habitat when he first set up the creatures as the pinnacle of reptiledom in 1842. He assumed that the cold-blooded dinosaurs needed less oxygen but more sunshine, suiting them to conditions that mammals could not tolerate.

But if dinosaurs were so well fitted to their environment, their undeniable extinction posed a sticky theological conundrum. If all of God's creations were perfect, why weren't they still alive? The biblical answer that any fossil animals not alive today were swept away in the unimaginable violence of the Genesis Flood held sway late into the century. However, the Flood and other presumed catastrophes receded, first in the face of Scottish geologist Charles Lyell's arguments begun in the 1830s that the Earth had been shaped by gradual, ordinary forces working over a vast timescale. They ebbed even further with the coming of Darwinism in the 1860s. Extinction--of any organism in general, and of the dinosaurs in particular--became one of the greatest unsolved mysteries of science.