Construction workers in Southern California have made a wild discovery. They were digging at a building site in San Timoteo Canyon   when they unearthed hundreds of ancient animal fossils. Researchers say the bones hold important clues about the history of the region. Nearly 1, 500 fossils were recovered from the dusty canyon. The remains are about 1.4 million years old. They include the bones of a new species of deer, several small rodents   and more. A giant cat fossil was also found. Scientists believe the animal was an ancestor of the saber- toothed tiger. Signs of plant life were uncovered as well. "This is a huge find," says Rick Greenwood, a scientist studying the site. "I don't think most people had any idea that those types of animals were wandering around here more than a million years ago." San Timoteo Canyon is located about 85 miles from Los Angeles. The area of the canyon where the fossils were found was once part of a green river valley. Today, the region is dry and plant life is rare. Most of the fossils are well preserved. Experts say a muddy lake bed may have trapped thirty animals that wandered over for a drink. The mud helped to protect the animal fossils. The remains are a million years older than those discovered at the famous La Brea Tar Pits in Los Angeles. Scientists studying the bones will be able to learn more about how the animals adapted to changes in the environment. "We have a confused view of what this time period was like, " says another scientist. "A discovery like this could really be an important contribution." About 35 different animal species are represented in the fossil collection. Scientists began removing bones from the site last fall. The project was completed this summer. Starting next year, the fossils will be on display at the Western Science Center in the nearby city of Hemet, California. What does the passage mainly focus on?
The secret of ancient animals' deaths. The preparation for a future fossil exhibition. A great discovery of fossils. The history of San Timoteo Canyon.
Question: Construction workers in Southern California have made a wild discovery. They were digging at a building site in San Timoteo Canyon   when they unearthed hundreds of ancient animal fossils. Researchers say the bones hold important clues about the history of the region. Nearly 1, 500 fossils were recovered from the dusty canyon. The remains are about 1.4 million years old. They include the bones of a new species of deer, several small rodents   and more. A giant cat fossil was also found. Scientists believe the animal was an ancestor of the saber- toothed tiger. Signs of plant life were uncovered as well. "This is a huge find," says Rick Greenwood, a scientist studying the site. "I don't think most people had any idea that those types of animals were wandering around here more than a million years ago." San Timoteo Canyon is located about 85 miles from Los Angeles. The area of the canyon where the fossils were found was once part of a green river valley. Today, the region is dry and plant life is rare. Most of the fossils are well preserved. Experts say a muddy lake bed may have trapped thirty animals that wandered over for a drink. The mud helped to protect the animal fossils. The remains are a million years older than those discovered at the famous La Brea Tar Pits in Los Angeles. Scientists studying the bones will be able to learn more about how the animals adapted to changes in the environment. "We have a confused view of what this time period was like, " says another scientist. "A discovery like this could really be an important contribution." About 35 different animal species are represented in the fossil collection. Scientists began removing bones from the site last fall. The project was completed this summer. Starting next year, the fossils will be on display at the Western Science Center in the nearby city of Hemet, California. What does the passage mainly focus on?
A. The secret of ancient animals' deaths.
B. The preparation for a future fossil exhibition.
C. A great discovery of fossils.
D. The history of San Timoteo Canyon.
Answer: