Question Corner: Why do herbivores have strong jaws?

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(Subscribe to Science For All, our weekly newsletter, where we aim to take the jargon out of science and put the fun in. .) Herbivores, or plant-eaters, are known to have strong jaws with broad, flat back teeth which help them grind and eat tough plant tissues. Some of the early herbivores including plant-eating dinosaurs also had strong jaws. (Nature Communications) has shown that herbivores developed strong jaws after the mass extinctions that happened millions of years ago. They had to eat different kinds of plants and chew harsher materials, so they evolved stronger jaws. The team measured hundreds of fossil jaws and compared their shapes with living animals. They tried to understand the bite force, mechanical advantage and how fast the jaws shut. The researchers note that as plants diversified during the Triassic era (252–201 million years ago) the herbivores also evolved to eat the new kinds of plants. The drying conditions in the Late Triassic, led to many softer plant groups becoming less common, and dry-adapted conifers spreading worldwide. These changes also drove patterns of extinction. The hardy herbivores thrived, as other herbivores died out.