Arizonasaurus was an archosaur from the Middle Triassic.

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

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

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, ...

Dinosaurs are the extinct relatives of birds that roamed the lands and seas of ancient Earth. They first appeared around 240 million to 230 million years ago in the Triassic Period, and went extinct ...

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 ...

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 ...

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 ...

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 ...