Amazing Animals: Dinosaur Quiz

The prevailing scientific view is that whether you're seeing a hummingbird, a robin, a flamingo or any other type of bird, you're seeing a descendant of dinosaurs.

Dinosaurs were a group of land animals that lived about 230 million years ago until about 60 million years ago. This spans the era of Earth's history known as the Mesozoic era, which includes the Triassic, Jurassic and Cretaceous periods.

Dinosaurs had four limbs, although some of them walked on just two legs.

Bumps, called quill barbs, on the bones mean the dinosaur had feathers -- some Velociraptor specimens have these barbs.

With computerized axial tomography (CAT) or CT scans, scientists can get a detailed view of inaccessible parts of skulls and other bones.

A popular theory that explains the extinction of dinosaurs at the K-T boundary -- the Alvarez theory -- states that an asteroid may have hit the Earth, causing massive shock waves, debris clouds and devastation. That impact, combined with geological changes and volcanic eruptions, most likely led to extinction of dinosaurs and about 50 percent of other species on Earth.

One lingering question, which encompasses several smaller questions, is whether dinosaurs were warm-blooded, like birds and mammals, or cold-blooded, like reptiles.

The dinosaurs that evolved into birds are theropods -- the three-toed dinosaurs that include Tyrannosaurus rex and Velociraptor. Ironically, these are members of the saurischian, or lizard-hipped, subgroup, rather than the ornithischian, or bird-hipped, group.

A popular theory for the extinction of dinosaurs, the Alvarez theory states that an asteroid may have hit the Earth, causing mass extinctions.

Many of the most well-known prehistoric reptiles, like the pterodactyl, aren't dinosaurs since dinosaurs must technically be four-legged land animals.