標題: Rockies fossils yield 8 new species [打印本頁] 作者:
fossilshk 時間: 2010-9-6 07:08 AM 標題: Rockies fossils yield 8 new species
A surprise fossil field at a glacier in B.C.'s Kootenay National Park contains at least eight new species that lived 505 million years ago.
Jean-Bernard Caron, curator of invertebrate paleontology at Toronto's Royal Ontario Museum, said the new arthropods (the group to which crabs and insects belong) and worms were found in an environment where paleontologists previously believed fossils could not be preserved or found.
The discovery means paleontologists might be able to find new fossils in similar environments that they had previously ignored.
"It opens up, I guess, a new terrain to explore," said Caron, who returned Thursday from a followup expedition to similar sites. "I think the chance to find new fossils in the future … will expand dramatically."
Descriptions of the new fossil field and the new species collected two years ago were published in the September issue of the journal Geology.
Fossils were first collected by a hiker walking on a trail near the Stanley Glacier in the park in the 1990s. The hiker contacted the Royal Ontario Museum, which sent researchers to collect fallen rock debris in the park in 1996.
Caron examined the rocks when he began working at the museum in 2006 and noticed that the fossils seemed to appear in a type of Rocky Mountain shale rock that hadn't been known for fossils before.
The rock dates back 505 million years ago, to the Middle Cambrian period — the same one represented by the Burgess Shale, which is located in the Rockies of Yoho National Park and considered one of the most important fossil fields in the world.
The Burgess Shale, located 40 kilometres northwest of the new fossil field, was once at the foot of an undersea cliff in tropical waters. Researchers believed the cliff provided an ideal environment for a diverse community of animals, and its harder rock prevented the fossil in the softer mud of the sea floor from being crushed by geological forces in hundreds of millions of years that followed.
The Stanley Glacier site represents a similar undersea environment, but with no evidence of any cliff nearby. It seems to have been above the Burgess Shale cliff.
Caron led a two-week expedition to the site in 2008, where researchers collected 2,000 specimens. Many of the species were previously known from other sites like the Burgess Shale, although some specimens were better preserved than any known before. However, eight were new, including a primitive arthropod predator that would have grabbed prey with its claws. It was named Stanleycaris after the glacier.
Caron said that's a lot of new species, considering that just 200 species have been discovered among more than 200,000 specimens collected from the Burgess Shale. He suggested the newly discovered animals may have been specifically adapted to that environment.
This August, Caron and his team went to look for similar sites along the same geological formation in the Rockies that yielded the Stanley Glacier site. They didn't find any new fossils this time, but plan to go back in the future.
