文章大意:本篇文章是一篇说明文。文章主要介绍了研究人员发现了生活在南极洲的一只巨鸟的 5000 万年前的骨头。通过对一些化石的研究,科学家们推测远古海鸟pelagornithid,可能是有史以来最大的飞鸟。
Imagine an albatross (信天翁) with a hacksaw for a mouth. Set that strange creature about 50 million years in the past and you’ve got the image of a pelagornithid, a group of ancient birds that included some of the largest flying birds of all time.
Now paleontologists (古生物学家) have uncovered in that group what may be the largest known flying birds ever, with wingspans of roughly six meters. By comparing a pair of polar fossils ( 化 石 ) to the remains of related birds, paleontologists have been able to identify the early history of huge fliers that were some of the first birds capable of flying across seas.
During the 1980s, University of California Berkeley paleontologist Peter Kloess says, scientists searching for Antarctic fossils found some delicate bird bones — a jaw and part of a foot from an ancient bird. Those bones made a long journey to California, and Kloess and his colleagues have researched them recently
The bird jaw, which came from a rock formation laid down over 37 million years ago, looks almost like a woodcutting tool rather than a bone. The jaw has a series of large and small spikes (尖刺), outgrowths of the beak (鸟喙) that are similar to teeth. Because of that feature, the paleontologists immediately identified the jaw as belonging to a pelagornithid, also known as bony-toothed birds that have a very long fossil record. The oldest pelagornithids evolved about 56 million years ago, and the most recent flew through the skies about two million years ago.
The foot bone came from another large Antarctic pelagornithid, but its real importance was in its age. The fossil was found in a rock layer in the La Meseta Formation, about 50 million years old. This falls within a time called the Eocene, when life had recovered from the asteroid-induced mass extinction and was thriving again. Together, the foot bone and the jaw indicate that large bony-toothed birds thrived in the Antarctic for millions of years.
Paleontologists have found bony-toothed birds from places all over the world, from New Zealand to South Carolina. The newly-described Antarctic fossils, though, are the oldest known and hint that these birds quickly diversified into a range of sizes within six million years of their origin. Previous studies have calculated that the largest of the bony-toothed birds could be near the limit of how big a bird could get and still fly, meaning these birds are the strongest competitors for the largest flying birds to ever fly.
Matched with the new data on the age of the fossils, Kloess says, “we can say that giant pelagornithids appeared earlier than previously known and that Antarctica saw a range of pelagornithid sizes from the early to late Eocene.” Small to large, bony-toothed birds were an important part of ancient Antarctic ecosystems.
Those impressive wings would have allowed the pelagornithids to range far and wide, flying long distances on outstretched wings. That helps explain why fossils from various species of pelagornithids have been found all over the world during their extended evolutionary period.
12. Why does the author mention the albatross in Paragraph 1?
A.To show its long evolutionary process. |
B.To help readers imagine an ancient bird. |
C.To compare it with a strange ancient bird. |
D.To show its relationship with an ancient bird. |
13. What helped the paleontologists identify the bird jaw?
A.Its special location. | B.Its unique appearance. |
C.Its living environment. | D.Its extremely large size. |
14. What can we learn about bony-toothed birds?
A.They all had a very short lifespan. |
B.They all faced considerable threats. |
C.They developed many survival skills. |
D.They evolved into various bird species. |
15. What does the text mainly talk about?
A.A recent research into Antarctic fossils. |
B.A brief introduction to rare bird species. |
C.The discovery of the largest flying birds. |
D.The origin of ancient bony-toothed birds. |