The scientists are digging for fossils（化石）. Fossilized bones tell the story of dinosaurs and animals that were once living creatures and appeared on Earth some 225 million years ago. Dinosaurs dominated the planet for 150 million years, much longer than people have existed.

Dinosaurs came in many shapes and sizes. The smallest dinosaur was less than 3 feet long. The largest were plant eating giants called Sauropods longer than a city bus.

Their weight closes to 50,000 pounds. To sustain its enormous body, it would endlessly grab branches and leaves and swallow them down a 20-foot throat. That is a neck as high as a two-storey house. With each step a weight greater than an eight ton ball would hit the earth. Despite their large size dinosaurs' share some characteristics with modern animals. Like today's reptiles（爬行动物）most, not all dinosaurs laid eggs. Its mate probably brought food to the nest like birds do. The mother tended her eggs and like a bird she placed them into a circle. Many plant eating dinosaurs lived in groups probably to defend themselves against the meat-eating or the dinosaurs who hunted them.

But 65 million years ago something happened that brought a sudden end to the dinosaur age. No one knows exactly why the dinosaurs suddenly disappeared. Most scientists think the killer came from outer space. A large object from outer space hit the earth causing a lot of dust in the atmosphere. The earth became dark and the dinosaurs died off. But scientists believe their descendents（后代）may live on. The skeletons（骨骼）of some dinosaurs are similar to modern birds. The common ancestor of these birds was probably a small two-legged meat-eating dinosaur. As the digging and research continues, each new find may help prove the dinosaurs did not really disappear after all. The birds are in fact living, breathing and flying dinosaurs.

Last summer, staff at the San Diego Zoo welcomed 41 baby turtles (海龟) from the Indian narrow-headed softshell turtle species, which is native to South Asia. It makes the Zoo the first officially recognized organization in North America to hatch (孵化) and raise the species.

Three Indian narrow-headed softshell turtles have been at the Zoo for over 20 years. All that time, zoo staff had been hoping they would one day reproduce. “This is a thrilling moment for us, and a big step forward in the protection of this species,” said Kim Gray, director of the Zoo.

The eggs were found in two separate nests (窝). Some of the turtles hatched in their habitat, while most of the eggs were stored in an artificial box to create the best conditions for survival. Turtle experts at the zoo say eggs in the habitat are often difficult to find, as the turtles like to lay their eggs overnight and cover them with dirt.

The species is listed as endangered on the International Union for Conservation of Nature’s Red List, though it’s unclear how many remain in the wild. Environ- mental pollution, habitat destruction, the international pet trade and human food harvesting have all led to the species’ reduction over the years.

“We have been caring for these turtles for a very long time, and part of that care is to gain a greater understanding of the species’natural history,” Kim Gray added. “With the knowledge we gain here at the Zoo, we can better assist our partners in India to help this essential species develop and grow in their native habitat.”

If you have ever found yourself concluding that intelligence is in short supply in the modern world, perhaps you are looking in the wrong place. There are still plenty of smarts to be found elsewhere.

You will be familiar with the cleverness of dolphins and chimpanzees. But what about wasps (黄蜂)? They can recognize human faces. Or mosquitoes? They can learn to avoid being killed by chemicals after a single taste.

Such an astonishing group of talent is rather unsettling, which raises fundamental questions like what actually is intelligence, how did it develop and how do the abilities of various organisms (生物) compare? Evaluating intelligence in nature is tricky, particularly in life forms that are very different from us. Now a group of neuroscientists, AI researchers and philosophers want to create a periodic table of intelligence similar to the one used to categorize the chemical elements. The chemical version sorts elements by their atomic (原子的) number or atomic mass. For intelligence, researchers are still looking for a criterion that is equally straightforward. But where to begin?

It certainly isn’t brain size, as was long thought. Behavior might be a better way to categorize cleverness. But testing for intelligence through behavior is difficult. Recognizing oneself in a mirror is seen as a sign of advanced cognition (认知). Dolphins and bats can do it — but dogs typically can’t. Does this reflect a lack of intelligence in dogs or perhaps something else, such as their reliance more on smell than vision. Likewise, many organisms live in environments that are obviously different from ours and so might use senses that we don’t even possess.

Nevertheless, the researchers behind the initiative think intelligence might become clearer through a combination of behavioral and neuroanatomical (神经解剖学的) features. “We’re going to ask, are there kinds of intelligence, and can we identify structural features that are organizational of those kinds of intelligence?” says Andrew Barron at Macquarie University. “If we can, then we are starting to identify things that can be thought of as possible dimensions of intelligence.”