It is not yet known why and when they went extinct.

With the death of David in 1839, the main male line went extinct.

Species are now being described just before or even after they have already gone extinct.

The species is thought to have gone extinct around the 16th century.

It went extinct in the beginning of the ice age.

So we can't feel sorry for a species going extinct?

"And they have gone extinct since 1989, when I started working here."

It went extinct around the turn of the 20th century.

It is believed to have gone extinct within the last 500 years.

Most of these went extinct by 5 to 10,000 years ago.

There have been conflicting reports whether the language has become extinct.

Most are considered endangered, and many have recently become extinct.

It became extinct ca. 1950, although some people remember a few words.

More important, they found that none of the original species in either river had become extinct.

It must surely have become extinct by 2.5 million years ago.

But he's working at a time when that species has become nearly extinct.

Many species have become extinct, and more than 1000 are endangered.

At the same time, some 200 native species have become extinct.

It may have become extinct there about 9000 years ago.

Their language and people are in the most danger of becoming extinct.