Arizonasaurus was an archosaur from the Middle Triassic.

Rock layers deposited before and after the major dinosaur extinction event 65 million years ago are surprisingly different.

The arrow doesn't just go in one direction." Dinosaurs became extinct after a large asteroid slammed into the Yucatan Peninsula. Scientists looking for evidence of the asteroid saw that the rocks ...

Human activity may be triggering the greatest extinction event since the asteroid impact that wiped out the dinosaurs, ...

Artist's rendering of the Chicxulub asteroid entering Earth's atmosphere 66 million years ago, triggering events that caused a mass extermination. Roger Harris/Science Photo library via Getty Images ...

Dinosaurs had such an immense impact on Earth that their sudden extinction led to wide-scale changes in landscapes—including the shape of rivers—and these changes are reflected in the geologic record, ...

The reptiles had such an "immense" impact on the planet that their sudden exit led to wide-scale changes in landscapes - including the shape of rivers, say American scientists. Geologists have long ...