Читать книгу Oceans For Dummies - Joseph Kraynak - Страница 65

During the Oligocene epoch (from 33.9 to 23 million years ago), ice sheets began to form again at the poles, which lowered sea levels, and more recognizable life-forms emerged:

 Grasslands flourished on land, making hoofed herbivores (such as rhinoceros and horses) more common, and ruminants (like cows) evolved to gobble up the grass.

 Big cats, dogs, horses, camels, eagles, raptors, elephants, and deer appear.

 Mastodons (the elephant’s nearly identical twin) and Paraceratherium, the largest land mammal of all time, wander the earth.

 Old world monkeys split from new world monkeys, and our ape ancestors enter the picture.

 Marine life mainly resembles what it is today, but as a whole, marine life diversity declines. Even so, during the Oligocene epoch, the ocean is home to baleen and toothed whales, desmostylians (vegetarian sea rhinos), and pinnipeds (seals, sea lions, and walruses).

No major event signified the end of the Oligocene epoch; it’s marked by small changes in fossils of algae and foraminifera (microscopic marine organisms). Nice to not have a mass extinction for a change, right?