As grasslands spread, some mammals evolved teeth modified for chewing coarse grass.

High-crowned, grazing teeth with complex tooth enamel resist wear. Cusps on tooth crowns form grinding ridges as jaws move from side-to-side.

Long legs evolved in many prairie mammals, enabling them to run faster to escape predators or to travel long distances in search of grass.

perissodactyls (per-ISS-o-dak-tils): plant-eating mammals with an odd number of toes, including rhinos and horses

New features:

  • large premolars chew like molars
  • long third toe supports body weight
When? 55 million years ago to present

artiodactyls (art-ee-o-DAK-tils): plant-eating mammals with an even number of toes, including camels, deer, and bison

New features:

  • long third and fourth toes support body weight
  • jaw joint high on the skull increases the leverage of chewing muscles
When? 55 million years ago to present

Transcript of Panel Text and Description of its Pictures Follows

Eat and Run!
A ruminant stomach, which evolved in some artiodactyls, extracts more nutrients from grasses. It is an important feature for a grazer that may need to flee from a predator at any moment. After it has been chewed and swallowed, grass ferments in a complex system of stomach pouches, and can be brought back to the mouth for a second chew later, when the danger has passed.

PICTURE CAPTIONS:

  • Neohipparion
  • Procamelus
  • Diagram showing common ancestry and evolution of rhinos/horses, camels/deer, and elephants from organisms with a unique ear structure.

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