Five Ways the World of the Dinosaurs Looked Different From Ours, Beyond the Presence of the 'Terrible Lizards'

From the pages of 19th-century novels to the screens playing summer blockbusters, countless stories have entertained the scenario. They almost always envision the great reptiles within thick and humid jungles, where tiny mammals shriek and scurry away from sharp-toothed shadows. But the forests and swamps where most dinosaurs roamed didn’t resemble modern habitats.

And the mammals of the time were not all so meek. Between the Triassic origin of the dinosaurs more than 235 million years ago and the cataclysmic asteroid strike 66 million years ago that left beaked birds as the only dinosaurs remaining, the Earth we now reside on was very different. Were you to travel back to the time of Tyrannosaurus rex, Apatosaurus or even the earliest dinosaurs, you would be able to tell you’d awoken in another era without ever seeing a “terrible lizard.” Here are five ways—beyond the dinosaurs’ presence—that the Earth in their heyday was different from the one we know today.

When the earliest dinosaurs began to step onto the Triassic scene, there were no flowering plants. Earth had no palm trees, grasses or citrus fruits. Many of the most numerous plants were larger and more varied relatives of those still around us today, such as ginkgo trees and horsetails.

These grew alongside now-extinct lineages, like bennettitales—spiky relatives of cycads that sprouted broad fronds and were likely some of the first plants to be pollinated by animals. For millions of years, through the Triassic and the Jurassic that followed, large dinosaurs kept such forests open and sunlit down to their trunks by feeding and trampling on plants. A sunny stand of conifers flanked by large horsetails and cycads sprouting up in an understory dotted by ferns was often the shape of a dinosaur-tended habitat.

It probably wasn’t until during the early Cretaceous, about 125 million years ago, that flowering plants as we know them today began to become more common. Some were wispy aquatic plants; others were relatives of today’s magnolias and so full of seeds that toothy birds foraged among their leaves. By 75 million years ago, palms grew alongside leafy flowering plants dotted with large fruit.

But it was only after the big asteroid strike that more modern forests of close-growing, canopy-forming trees began to pop up, creating thick habitats where our primate ancestors evolved some of the key traits we still possess. Our modern world can be a hot one, but the dinosaurs’ world was often hotter still, with sweltering stretches when the poles lacked ice and sea levels rose to the point of splitting continents in two. The entire span of the Mesozoic—the Age of Dinosaurs, from Triassic to Cretaceous—was a very long time, nearly three times as long as the post-asteroid impact history of the planet.