Some Dinosaurs Were Dealt a Slow Death

Some dinosaur species were declining long before the 150-million-year-long Age of Dinosaurs ended, scientists find.

Apparently large herbivores such as Triceratops and the duck-billed dinosaurs saw a long-term decline before the catastrophe, but carnivores and other plant-eaters, such as giant sauropods, did not, researchers said. Why some dinosaurs were on their way out while others still thrived just before "the end" may have to do with their locations — whether they lived in North America or Asia, for instance.

The demise of all dinosaurs except birds came about 65 million years ago, when researchers think a giant meteor collided with Earth. Still, it was unclear if mass extinctions started gradually before the impact, perhaps due to volcanoes or other forces

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