How do we know that these animals were active at night?
Fossils do not tell us whether animals were active by day or night. But we know that in present-day desert areas, many animals are active during the dark hours in order to take advantage of lower nighttime temperatures and higher humidity.

How do we know that these animals had feathers?
Recent fossil evidence from Mongolia and China reveals that some birdlike dinosaurs had filaments or feathers on parts or all of their bodies. These structures are chemically and structurally identical to modern feathers. The color and style of the feathers here are artistic interpretations.

How do we know what color dinosaurs were?
We don't! Fossilized bones provide no clues to skin or feather color. Even rare specimens of fossilized dinosaur skin, which retain skin texture, long ago lost their original color. Dinosaur artists sometimes make guesses based on modern animals including lizards, birds and mammals.

How did these animals survive in a desert?
Then as now, many animals adapted to desert conditions. Among the sand dunes here 80 million years ago were streams and seasonal shallow lakes where animals could drink. Plant eaters devoured the shrubs and small trees that grew at the water's edge, and meat eaters found abundant prey.

Why are fossils of dinosaur embryos and hatchlings so rare?
The bones of tiny dinosaurs have rarely been preserved, either because they were simply too fragile or because predators often ate the young, leaving few remains. Some researchers think that dinosaurs, like birds, grew extremely fast, so babies reached their adult sizes quickly.

What did oviraptorids eat?
It's difficult to determine the dietary habits of animals that have been dead for tens of millions of years, but in this case there is a piece of unusually good evidence. The bones of a small lizard were found near the stomach of an Oviraptor philoceratops, and as lizards make up the diets of a number of birds, it's likely that it was this birdlike dinosaur's last meal.

What is a bird?
Today, birds are generally recognized as feathered vertebrates that lay eggs and sit on nests; most modern birds also have the ability to fly. In addition to these attributes, all birds have feet with three primary toes, hollow bones, bony breastbones and "S"-shaped necks. Recently discovered dinosaur fossils, including many seen in this exhibition, reveal that many of these bird characteristics were present in theropod dinosaurs long before birds evolved. Scientists now acknowledge that the term "bird" is imprecise, and whether or not certain animals are birds is open to debate.

Why are there so few fossils of ancient birds?
Birds have hollow, lightweight bones, ideal for flight-but poor for fossilization. The fragile bones break quickly after a bird dies, and they are preserved as fossils only under extraordinary circumstances.

What is a mammal?
Most people recognize mammals as warm-blooded animals that produce milk for their young, and scientists further classify mammals using additional features. Like their ancient relatives, all living mammals have three middle ear bones. Modern mammals also have hair or fur on their bodies, and when well-developed teeth are present, they are differentiated into incisors, canines, premolars and molars. Today's diverse mammals are divided into three major groups: monotremes, egg layers such as the platypus and echidna; marsupials, pouched animals including the opossum and kangaroo; and the placentals, which range from rats and bats to whales and humans.