Fossils illustrate evolution of life

When it comes to life on Earth, perhaps we should consider ourselves lucky — the largest land and sea creatures of today don’t tend to devour people. But had we shared the planet with such terrors as Giganotosaurus and the enormous shark Carcharocles megalodon, we probably wouldn’t have fared so well. Paleontologist Donald Prothero introduces readers to these beasts and others in The Story of Life in 25 Fossils.

The gee-whiz aspects of big dinosaurs and other bizarre critters aren’t the meat of the book; it’s Prothero’s careful description of 25 fossils that offer an overview of the progression of plants and animals in the last 3.5 billion years.

Prothero starts at life’s beginning, with mats of microbes that ruled the world until roughly 600 million years ago. Eventually those microbes morphed into multicelled sea creatures that looked liked worms, jellies and underwater ferns. From there, an explosion of creatures occurred, producing everything from early mollusks and sponges to nightmarish sea creatures that now carry names like Hallucigenia (SN Online: 6/24/15). Later came land plants, fish that grew the size of Carcharocles and fish that crawled out of water. Those critters branched into frogs, turtles and snakes. Ultimately, the animals transitioned into dinosaurs, birds and mammals.

Chapters chronicle critical stages of evolution in which spineless animals developed backbones and animal groups diverged into arthropods, amphibians, reptiles, whales, humanlike ancestors and much more. The chapters are short and packed with details, which sometimes tangle into tangents.

Still, the tangents act as good teasers, briskly walking readers through the whirlwind of life on Earth and celebrating the diversity of creatures that once existed. That celebration ends abruptly, however, as Prothero reminds readers that Homo sapiens is now the terror of the planet, threatening to drive nearly all species, including itself, extinct.